Monthly Personal Loan Repayment Calculator

This monthly personal loan repayment calculator estimates your fixed monthly payment and total interest from the amount borrowed, annual percentage rate (APR), and loan term. Enter those three figures to see the scheduled payment under a standard fixed-rate repayment formula.

Formula

The calculator uses the standard level-payment formula for a loan with a fixed periodic interest rate and equal monthly payments. In symbols:

Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount borrowed, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 1,200. The APR is entered as a percentage per year.
• n is the number of monthly payments: loan term in years × 12.

Total interest is estimated as the monthly payment multiplied by the number of payments, minus the amount borrowed: total interest = monthly payment × n − P. This calculator displays the payment and interest to the nearest cent. The displayed total interest uses the displayed, cent-rounded monthly payment multiplied by the full payment count, so rounding can cause a small difference from a lender’s final accounting.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a five-year term:

1. Convert the APR to a monthly decimal rate: 8 ÷ 1,200 = 0.0066667.
2. Find the number of payments: 5 × 12 = 60.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] = approximately $405.53 per month.
4. Calculate total interest using the displayed payment: $405.53 × 60 − $20,000 = $4,331.80.

These are estimates for the stated assumptions; the payment formula’s full-precision result is rounded to cents for the displayed monthly amount.

Assumptions

• The interest rate stays fixed for the full loan term.
• Payments are equal, made monthly, and occur at the end of each monthly period.
• Interest compounds monthly using the APR divided by 12.
• Fees, taxes, insurance, payment-protection products, and other charges are not included unless they are included in the amount borrowed or reflected in the APR provided.
• No extra payments, missed payments, or changes to the schedule are modelled.

When to Use a Monthly Payment Estimate

Use the calculator to translate a proposed loan amount, quoted APR, and term into an estimated scheduled payment. It can also help explain how the term affects the payment and interest: with the same amount and APR, spreading repayment over more months generally lowers the required monthly payment but increases the number of months interest is charged. The result is a mathematical estimate, not a loan offer or a determination of approval.

Enter the loan principal you expect to finance, rather than a monthly payment target. If a lender quotes a separate fee that will be added to the balance, the amount financed may be higher than the cash you receive. Check the lender’s disclosure to identify the amount financed and the APR used for the offer. Use the quoted APR and term in the same units as the calculator: APR as a yearly percentage, and term in years.

How to Read the Result

Monthly payment is the estimated amount applied each month under the fixed-payment model. Each scheduled payment covers interest accrued for that period and reduces principal; the interest portion generally declines over time as the outstanding balance falls. The payment does not mean that the same amount reduces principal every month.

Total interest estimates the interest paid over all scheduled payments. It is not the total amount repaid: estimated principal plus interest equals $24,331.80 in the default example. A loan’s actual payment schedule can differ if its balance, rate, fees, payment dates, or servicing calculations differ from the assumptions.

Common Input Problems and Limitations

• Confusing APR with a monthly rate: enter the annual percentage as a number such as 8, not 0.08 or 0.0067. The calculator converts it to a monthly rate.
• Entering months as years: a 36-month term is 3 years. Multiplying the entered years by 12 determines the payment count.
• Leaving out financed costs: if a charge is rolled into the balance, include it in the loan amount only when that matches the figures you are estimating.
• Assuming a variable rate is fixed: this formula cannot predict payment changes when a rate can reset.
• Rounding or schedule differences: payment dates, daily interest methods, a final adjusted payment, or lender-specific rounding may make actual figures differ by a small amount.

The formula also assumes a fully amortizing loan: regular payments are sufficient to repay principal and interest by the end of the stated term. It does not calculate a payoff quote, late charges, or the effect of additional payments. To assess those items, use the lender’s stated schedule and terms rather than treating this estimate as a statement of the account balance.

Frequently Asked Questions

How do I calculate a monthly personal loan payment?
Convert APR to a monthly decimal by dividing it by 1,200, convert years to months, and apply the level-payment formula shown above. This calculator performs those steps and rounds the monthly result to cents.

Does the calculator include fees?
No separate fee input is included. Fees are not added automatically; check whether the lender includes any charge in the amount financed or APR, and use the figures that match the estimate you want.

Why does a longer term usually mean more total interest?
A longer term means more monthly periods in which interest can accrue. Although the scheduled payment may be lower with more payments, the total interest can be higher when the principal and rate stay the same.

Is APR the same as the monthly interest rate?
No. APR is entered as an annual percentage. This calculation uses APR divided by 12 as the monthly rate, expressed as a decimal.

Will my actual payment match this estimate?
Not necessarily. The estimate assumes a fixed rate, equal end-of-month payments, and no separately modelled charges or schedule changes. The lender’s disclosure gives the figures for its specific loan.

This result is an estimate, and the lender’s disclosure gives the exact figures.

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2