401k Loan Calculator

For someone facing a genuine financial emergency with limited other options, a 401k loan can seem like the cleanest solution available. But this framing — borrowing from yourself — obscures the real costs, which are not paid to a bank but are paid instead in the form of permanently diminished retirement savings, lost investment growth that can never be recovered, and a cascade of tax consequences if the loan goes wrong.

The average American worker who takes a 401k loan does not fully understand what the loan actually costs. They see the paycheck deduction for repayment, they note that the interest comes back to their own account, and they conclude the cost is minimal or even zero. What they do not see is the opportunity cost — the compounding investment returns that the borrowed money would have generated if it had stayed invested — which is the true price of a 401k loan and is almost always far larger than the interest rate suggests.

This free 401k Loan Calculator computes your monthly payment, total repayment cost, projected retirement impact, and the true break-even comparison against alternative borrowing sources. This guide explains how 401k loans work under IRS rules, how the payment formula operates, what the real costs are, when a 401k loan is genuinely justified, and when it is almost certainly a mistake. No sign-up required.

How 401k Loans Work

The Basic Structure

A 401k loan allows you to borrow money from your own vested 401k balance and repay it — with interest — over time through payroll deductions. The loan is not a withdrawal; it is a formal loan arrangement between you and your plan. The plan administrator processes the request, the money is liquidated from your investments and distributed to you, and repayments are deducted from your paycheck and redeposited into your account with interest.

Because the transaction stays entirely within the plan — you are borrowing from and repaying to yourself — it does not require IRS approval, does not trigger income tax or early withdrawal penalties at the time of distribution, and does not appear on your credit report. From a bureaucratic standpoint, it is the easiest loan you can obtain. From a financial planning standpoint, it is one of the most costly.

IRS Rules Governing 401k Loans

The IRS sets strict boundaries on 401k loans that all plans must follow:

Maximum loan amount: You can borrow the lesser of $50,000 or 50% of your vested account balance. If your vested balance is $80,000, the maximum loan is $40,000. If your vested balance is $120,000 or more, the maximum loan is $50,000. Note that the $50,000 limit is reduced by the highest outstanding 401k loan balance you had in the 12 months before the new loan — so if you repaid a $20,000 loan three months ago, your new maximum is $30,000 ($50,000 − $20,000).

Repayment term: Most 401k loans must be repaid within five years. The only exception is a loan used to purchase your primary residence, which many plans allow to be repaid over a longer period — typically 10 to 15 years, at the plan administrator’s discretion. The five-year rule is a hard IRS requirement for all other purposes.

Repayment schedule: Repayments must be made at least quarterly. In practice, virtually all plans require monthly payroll deductions, which satisfies the quarterly requirement automatically.

Interest rate: The plan must charge a reasonable rate of interest. Most plans use the prime rate plus 1% to 2%, which as of 2024 typically means rates in the 8% to 10% range. The interest is paid back into your own account, not to a lender.

Loan limits per account: Most plans allow only one or two outstanding loans at a time. You cannot take unlimited loans to bypass the $50,000 cap.

Use our Maximum Loan Amount Calculator to estimate how much you can borrow based on income, debt, interest rates, and repayment terms. It helps you plan financing decisions, affordability limits, and smarter borrowing strategies.

What Happens If You Leave Your Job

This is the most important risk in any 401k loan and the one most frequently overlooked. If you leave your employer — whether voluntarily, through layoff, or termination — your 401k loan typically becomes due in full within 60 to 90 days of your separation date. If you cannot repay the full outstanding balance by that deadline, the remaining balance is treated as a taxable distribution. You will owe ordinary income tax on the full amount at your current marginal rate, and if you are under age 59½, an additional 10% early withdrawal penalty.

The Tax Cuts and Jobs Act of 2017 extended the deadline for repaying a 401k loan after job separation to the due date of your federal tax return for the year you left (including extensions), which gives most people until October 15 of the following year rather than 60 to 90 days. This is a meaningful improvement, but it does not eliminate the risk — if you cannot repay the loan by the extended deadline, the tax consequences remain fully intact.

The True Cost of a 401k Loan

The Double Taxation Myth — Partially True

A commonly cited disadvantage of 401k loans is that the interest payments are subject to double taxation — you repay the loan with after-tax dollars (paycheck deductions), and then when you withdraw the money in retirement, you pay income tax again on the same dollars. This is technically correct, but it is only a partial picture of the true cost and can be overstated. All money you eventually withdraw from a traditional 401k is taxed as ordinary income, whether or not it passed through a loan cycle. The true additional cost from double taxation is the tax on the interest portion of your repayments — not the principal repayments, which would have been taxed when withdrawn in retirement regardless.

The more significant and often underappreciated cost is the opportunity cost of the invested funds — and this is almost always much larger than the double taxation effect.

The Opportunity Cost — The Real Price

When you take a 401k loan, the borrowed amount is liquidated from your investments and sits out of the market for the duration of the loan. During that time, it earns only the interest rate you are paying back to yourself — typically prime plus 1% to 2% — rather than the returns it would have generated if left invested in a diversified portfolio. Over the long run, a diversified stock and bond portfolio has historically returned approximately 7% to 8% annually in inflation-adjusted terms. The gap between those market returns and your loan interest rate is the opportunity cost — and it compounds annually for the duration of the loan and for every subsequent year until retirement.

Example: You borrow $25,000 from your 401k for five years at 9% interest. Your account is 25 years from retirement.

• Interest you pay back to yourself over 5 years at 9%: approximately $6,200
• Market returns you would have earned on $25,000 over 5 years at 7% annual return: approximately $10,100
• Opportunity cost of the loan: approximately $3,900 during the loan period

That $3,900 difference in the account at the end of year 5 then compounds for the remaining 20 years until retirement:

• $3,900 compounding at 7% for 20 years = approximately $15,100 of permanently lost retirement wealth

The true cost of a $25,000 401k loan is not the interest payments that came back into your account — it is approximately $15,100 in retirement savings you will never get back, simply because the money was out of the market for five years during a period that had 20 more years to compound. This is the number that the 401k loan calculator makes visible, and it is the number that most people never see before they borrow.

The Payroll Deduction Squeeze

401k loans are repaid through automatic payroll deductions — money that comes out of your take-home pay before you ever see it. This creates a real cash flow squeeze: your net pay is reduced by the loan repayment amount, which comes on top of your regular 401k contribution if you continue contributing. Many borrowers reduce or stop their regular 401k contributions during the loan repayment period to maintain take-home pay, which compounds the retirement savings damage. Not only is the borrowed amount sitting out of the market, but ongoing contributions are also reduced or eliminated — creating a double reduction in new money flowing into the account during the repayment years.

The 401k Loan Payment Formula

How Monthly Payments Are Calculated

401k loan repayments are calculated using the standard loan amortization formula — the same formula that applies to any instalment loan:

M = P × [r(1 + r)ⁿ] ÷ [(1 + r)ⁿ − 1]

Where:

• M = monthly payment
• P = loan principal (amount borrowed)
• r = monthly interest rate (annual rate ÷ 12)
• n = number of months in the repayment term

Step-by-Step Worked Example

Scenario: You borrow $20,000 from your 401k at 9% interest (prime + 1.5%) over 60 months (5 years).

Monthly Rate: 9% ÷ 12 = 0.75% = 0.0075

Formula: M = $20,000 × [0.0075 × (1.0075)⁶⁰] ÷ [(1.0075)⁶⁰ − 1]

(1.0075)⁶⁰ = 1.5657

M = $20,000 × [0.0075 × 1.5657] ÷ [1.5657 − 1] M = $20,000 × [0.011743] ÷ [0.5657] M = $20,000 × 0.020758 M = $415.17 per month

Total Repaid: $415.17 × 60 = $24,910.20 Total Interest Returned to Account: $24,910.20 − $20,000 = $4,910.20

The interest of $4,910.20 comes back into your own 401k account. But the opportunity cost — the market returns you gave up by having $20,000 out of the market for five years — at 7% annual return is approximately $8,078. You paid $4,910 in interest to yourself and gave up $8,078 in market returns: a net cost of approximately $3,168 during the loan period alone, before that difference compounds for the remaining years to retirement.

Use our Interest Calculator to calculate simple interest, compound interest, loan costs, and total repayment amounts with accurate results. It helps you compare borrowing options, investment returns, and overall financial planning decisions.

Monthly Payment Reference Table

Use our Amortization Calculator to calculate monthly loan payments, interest costs, repayment schedules, and remaining balances with detailed breakdowns. It helps you understand loan payoff timelines and manage debt more effectively.

Retirement Impact — What the Loan Really Costs Over Time

The Compounding Opportunity Cost by Loan Size and Years to Retirement

The longer you have until retirement, the more damaging a 401k loan becomes — because the opportunity cost has more years to compound. The table below shows the approximate permanent retirement savings reduction from taking a $20,000 401k loan at 9% over 60 months, assuming 7% annual investment returns on the foregone balance:

A $20,000 loan taken at age 35 by someone planning to retire at 65 permanently reduces retirement savings by approximately $17,400 — nearly 87% of the original loan amount — simply from the opportunity cost of the borrowed funds being out of the market for five years during a period that had 25 more years to compound. This is the calculation that most borrowers never make, and it explains why financial planners consistently advise exhausting every other option before touching retirement savings.

Use our Compound Interest Calculator to calculate investment growth, earned interest, and future account value with accurate compounding results. It helps you understand long-term wealth building, savings growth, and smarter financial planning strategies.

How to Use the 401k Loan Calculator

Step 1 — Enter Your Loan Amount

Enter the amount you intend to borrow, up to the IRS maximum of the lesser of $50,000 or 50% of your vested balance. If you are unsure of your vested balance, check your most recent account statement or log into your plan’s online portal. The vested balance is the portion of your account that you own outright — for most employees who have been with their employer for several years, this is 100% of the account balance; for newer employees at companies with vesting schedules, it may be a smaller percentage.

Step 2 — Enter the Interest Rate and Loan Term

Your plan administrator will specify the interest rate for your loan — most plans use the prime rate plus a fixed margin of 1% to 2%. Enter the annual interest rate. For the loan term, enter the number of months for repayment. The IRS maximum for most purposes is 60 months (5 years). If you are borrowing for a primary home purchase and your plan allows an extended term, enter the longer term your plan permits.

Step 3 — Enter Your Current Account Balance and Years to Retirement

These two inputs drive the retirement impact calculation. Enter your current total 401k account balance (not just the vested balance — the total balance shows the full account that will be affected by the loan). Then enter the number of years until your expected retirement date. The calculator uses an assumed rate of return — typically 7% annually as a long-term historical average for diversified retirement portfolios — to project what your account would have grown to at retirement with and without the loan, showing the lifetime wealth difference.

Step 4 — Enter Your Tax Rate (Optional)

For the double taxation analysis, enter your current marginal federal income tax rate. This allows the calculator to quantify the additional tax cost on the interest payments that will eventually be taxed again at withdrawal, separate from the opportunity cost component.

Step 5 — Review All Outputs

The calculator returns:

• Monthly payment amount
• Total interest returned to your account
• Net opportunity cost (market returns foregone minus interest returned)
• Estimated reduction in retirement balance at target retirement date
• Break-even comparison: 401k loan versus personal loan or home equity borrowing at equivalent amounts
• Recommended action based on years to retirement and loan size

When a 401k Loan May Be Justified

Genuine Financial Emergencies With No Other Options

A 401k loan is most defensible when it is the last available option in a genuine financial emergency — preventing home foreclosure, avoiding bankruptcy, or covering a medical expense that cannot be deferred and cannot be financed through any other means. In these situations, the long-term cost of the loan must be weighed against an immediate, concrete harm that cannot be avoided by any other means. A person facing foreclosure on their primary residence who has no home equity, no available credit, and no other savings has a legitimate case for accessing retirement funds — the alternative of losing the home carries costs that may exceed the retirement savings damage.

Avoiding High-Interest Debt

If the alternative to a 401k loan is borrowing on a high-interest credit card at 24% to 29% APR, the mathematics may favor the 401k loan — depending on the amount, the term, the years to retirement, and how quickly the credit card would otherwise be paid off. This analysis requires actually running both scenarios through a calculator. Do not assume a 401k loan is cheaper than high-interest debt without computing both paths explicitly. In some cases — particularly for older workers close to retirement — the tax-adjusted cost of the 401k loan is comparable to or exceeds the credit card cost when opportunity cost is properly accounted for.

Use our Debt-to-Income Ratio Calculator to calculate your monthly debt obligations compared to your income with accurate percentage results. It helps you evaluate loan eligibility, financial stability, and overall borrowing capacity.

Primary Home Purchase (Extended Term)

For workers whose plans permit extended loan terms for primary residence purchases, a 401k loan can serve as a source of down payment funds when combined with a first mortgage. This is one of the few uses where the longer compounding runway of retirement savings is partially offset by the equity being built in the real estate — the down payment funds are not spent; they become equity in an asset. That said, first-time homebuyer assistance programs, FHA loans with 3.5% down, and state housing finance agency programs should all be exhausted before using retirement savings for a down payment.

Use our Home Mortgage Calculator to calculate monthly mortgage payments, interest costs, loan terms, and total home financing expenses with accurate estimates. It helps you plan home purchases, compare mortgage options, and manage long-term housing costs.

Short-Term Liquidity With Immediate Repayment Capacity

If you know with high confidence that you will repay the loan significantly faster than the five-year term — for example, you are expecting a bonus, an inheritance, or a large commission payment within 12 to 18 months — the opportunity cost can be materially lower than the five-year projection suggests. A loan repaid in 18 months has far less impact than the same loan repaid over 60 months. However, this scenario depends on the anticipated funds actually materializing on schedule, which introduces its own risks.

When a 401k Loan Is Almost Certainly a Mistake

Job Insecurity or Likelihood of Job Change

If there is any meaningful probability that you will change jobs, be laid off, or retire before the loan is fully repaid, a 401k loan is extremely risky. The job-separation rule — which makes the outstanding balance due within the tax filing deadline for the year of separation — means that a five-year loan can become due within months if your employment situation changes. Borrowers who cannot repay the balance face income tax plus a 10% early withdrawal penalty on the entire outstanding amount — potentially turning a $20,000 loan into a $26,000 to $30,000 tax bill depending on their marginal rate. Never take a 401k loan if your job security is uncertain.

Young Workers With Long Compounding Horizons

The younger you are, the more damaging a 401k loan is relative to any other borrowing alternative. A 28-year-old with 37 years until retirement who borrows $15,000 from their 401k is giving up potentially $30,000 to $50,000 in retirement wealth at 7% compounding over 37 years — for a loan that a credit union might have offered at 8% to 10% with no retirement impact whatsoever. For workers under 40 with 25 or more years to retirement, the opportunity cost argument against 401k loans is overwhelming in almost every scenario.

Funding Non-Essential Expenses

Taking a 401k loan to finance a vacation, a new car, home entertainment, or other discretionary spending is almost impossible to justify financially. These are expenses that can be deferred, saved for, or financed through appropriate consumer credit. The retirement savings damage from using a 401k loan for lifestyle spending is real and permanent; the purchase itself is transient. A car purchased with a 401k loan may be worth $8,000 in five years when the loan is paid off; the retirement savings reduction attributable to that loan may be $20,000 or more by retirement.

When You Have Other Low-Cost Options Available

Before taking a 401k loan, exhaust these alternatives in order of financial impact:

Emergency fund: The purpose of an emergency fund is precisely to avoid touching retirement savings. Three to six months of expenses held in a high-yield savings account is the first line of defense.

Home equity line of credit (HELOC) or home equity loan: For homeowners with equity, home equity borrowing is typically priced close to the prime rate, the interest may be tax-deductible if used for home improvements, and — critically — it does not remove funds from the compounding power of a retirement account.

Personal loan from a credit union: Credit unions frequently offer unsecured personal loans at rates of 7% to 12% for members with reasonable credit. No retirement impact, no job-separation risk, no opportunity cost on retirement savings.

0% APR credit card (balance transfer or purchase): For short-term borrowing needs that can be repaid within 12 to 21 months, a 0% introductory APR credit card offer eliminates the interest cost entirely — and eliminates all retirement impact.

Roth IRA contributions withdrawal: Contributions (not earnings) to a Roth IRA can be withdrawn at any time without tax or penalty. If you have a Roth IRA, withdrawing contributions before touching your 401k preserves more of your retirement savings trajectory because Roth contributions have already been taxed and their withdrawal does not trigger the cascading tax consequences of a failed 401k loan.

401k Loan vs. 401k Early Withdrawal — A Critical Distinction

Some workers, particularly those under financial stress, treat a 401k loan and a 401k early hardship withdrawal as equivalent options. They are not — and the differences are significant.

A 401k loan is not taxed when disbursed, does not trigger the 10% early withdrawal penalty, must be repaid, and returns money to the account with interest. It is a borrowing transaction, not a distribution.

A 401k early withdrawal is fully taxed as ordinary income in the year of the distribution, triggers an additional 10% penalty if you are under age 59½ (reduced to 0% if you qualify for a hardship exemption under specific IRS criteria), does not need to be repaid, and permanently removes both the principal and all future investment returns from your retirement account.

For anyone under 59½ who does not qualify for a hardship exemption, an early withdrawal is almost never the right choice. A $20,000 withdrawal by someone in the 22% federal tax bracket plus a 5% state rate and 10% penalty faces an effective 37% immediate tax cost — leaving only $12,600 of the $20,000 in hand after taxes and penalties. A loan of the same amount leaves the full $20,000 in hand with no immediate tax cost.

Strategies to Minimize 401k Loan Damage

Make Extra Payments Whenever Possible

Most plan administrators allow additional voluntary payments beyond the required monthly deduction. Making extra payments accelerates the reduction of the outstanding balance, shortens the effective loan term, and returns the money to investment sooner — reducing the opportunity cost proportionally. Even one extra payment per year can shorten a five-year loan meaningfully and reduce the total retirement savings impact.

Do Not Reduce Your Regular Contributions

The most damaging behavior during a 401k loan repayment period is stopping or reducing regular 401k contributions to compensate for the reduced take-home pay. This doubles the retirement savings damage: the borrowed amount is already out of the market, and now new money is also not flowing in. If you are receiving an employer match, reducing contributions to zero also forfeits the match — which is an immediate 50% to 100% loss on the contribution, representing the highest-cost financial decision most employees can make.

Maintain your regular contribution at least up to the employer match threshold throughout the loan repayment period, even if it is uncomfortable in the short run. The compound growth on contributions during the repayment years and beyond significantly mitigates the overall retirement savings impact.

Repay the Full Balance Immediately if You Leave Your Job

If you leave your employer before the loan is repaid and have any means of repaying the outstanding balance — emergency fund, borrowing from a family member, taking a personal loan from your new employer’s credit union — do so before the tax filing deadline for the year of separation. The tax and penalty cost of a failed loan rollover is almost always more expensive than any alternative repayment source. Running the numbers: a $15,000 outstanding balance converted to a taxable distribution at a 22% federal rate plus 5% state rate plus 10% penalty costs approximately $5,550 in taxes and penalties — that is $5,550 to avoid $15,000 worth of debt. Pay it off.

Final Thoughts

A 401k loan is not free money borrowed from yourself — it is borrowed growth, and growth is the most valuable thing in a retirement account. The interest you pay back is far less than the compound investment returns you give up by having the money out of the market, and that gap compounds for every subsequent year until retirement. Before taking a 401k loan, run the full retirement impact calculation — not just the monthly payment — and exhaust every alternative borrowing option first. If you do take a loan, keep your contributions going, make extra payments, and protect yourself from the job-separation risk by maintaining an emergency fund sufficient to cover the outstanding balance.

Use our free 401k Calculator to model your specific scenario — different loan amounts, terms, account balances, and retirement timelines — and see the full retirement impact before you decide.

Frequently Asked Questions

How much can I borrow from my 401k?

The IRS allows you to borrow the lesser of $50,000 or 50% of your vested account balance. The $50,000 maximum is reduced by the highest outstanding 401k loan balance you had in the prior 12 months. If your vested balance is below $10,000, some plans allow you to borrow up to $10,000 even though it exceeds 50% of the balance. Check your plan documents for specific rules, as individual plans may set lower limits than the IRS maximum.

What happens to my 401k loan if I lose my job?

If you leave your employer for any reason — resignation, layoff, termination, or retirement — your outstanding 401k loan balance is generally due by the tax filing deadline (including extensions) for the year of your separation, typically October 15 of the following year under post-2017 rules. If you cannot repay the balance by that deadline, it is treated as a taxable distribution: you owe ordinary income tax on the full amount, plus a 10% early withdrawal penalty if you are under age 59½. This is the most significant risk of a 401k loan.

Does a 401k loan affect my credit score?

No. A 401k loan is not reported to credit bureaus and does not appear on your credit report. It has no impact — positive or negative — on your credit score. This is one of the genuinely distinct advantages of 401k loans over personal loans or credit cards, particularly for borrowers with challenged credit. However, a 401k loan default — where the outstanding balance is treated as a distribution — also does not appear on credit reports, so the damage from a failed 401k loan is purely financial and tax-related, not credit-related.

Is the interest I pay on a 401k loan tax-deductible?

No. The interest you pay on a 401k loan is paid with after-tax dollars and is not deductible as a home mortgage interest deduction or any other deduction, even if the loan was used for a home purchase. This is part of the double taxation issue with 401k loans: you repay with after-tax dollars, and then when you withdraw in retirement, the same money (including the interest) is taxed again as ordinary income.

Can I have two 401k loans at the same time?

It depends on your plan. Many plans permit a maximum of two outstanding loans simultaneously, but some plans restrict borrowers to one loan at a time. Even if your plan allows two loans, the combined outstanding balance cannot exceed the IRS maximum of $50,000 or 50% of your vested balance, and the $50,000 cap is reduced by your highest outstanding balance in the prior 12 months. Check your plan summary plan description for the specific rules that apply to you.

Should I take a 401k loan or a personal loan?

In most cases, a personal loan from a bank or credit union is preferable to a 401k loan for workers with reasonable credit and more than 10 years until retirement. A personal loan does not remove funds from the compounding growth of your retirement account, does not create job-separation risk, and is typically available at rates comparable to 401k loan rates for borrowers with good credit. The analysis changes for workers with poor credit who face very high personal loan rates, or for workers in genuine emergencies with no credit access — in those cases, the 401k loan may be the better option despite its retirement savings impact. Always run the retirement impact numbers before deciding.

What is the difference between a 401k loan and a 401k hardship withdrawal?

A 401k loan must be repaid with interest, is not taxed at distribution, carries no early withdrawal penalty, and returns the money to your account. A 401k hardship withdrawal does not need to be repaid, is taxed as ordinary income in the year taken, and carries a 10% early withdrawal penalty if you are under 59½ (unless an IRS exemption applies). Hardship withdrawals permanently remove the money and all future investment returns from your account. A hardship withdrawal should be an absolute last resort — the combined tax and penalty cost can consume 30%–40% of the withdrawn amount immediately, making it one of the most expensive forms of borrowing available.

Can I repay my 401k loan early?

Yes, and you should if possible. 401k loans typically carry no prepayment penalty, so you can pay them off ahead of schedule at any time. Early repayment returns the funds to investment sooner, reduces the total opportunity cost, and eliminates the ongoing job-separation risk associated with carrying an outstanding balance. If you receive a bonus, tax refund, or other windfall, applying it to accelerate your 401k loan repayment is almost always a financially sound decision compared to using the funds for discretionary spending.

This guide is part of Intelligent Calculator’s Finance suite — built on IRS retirement plan guidelines, financial planning best practices, and retirement savings methodology. Use our free 401k Calculator and full suite of retirement planning tools. Free. No sign-up required.