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Repayment Calculator

See the full amortization schedule for any loan with interactive year and month views. Add extra payments to see time and interest saved, then export to CSV.

✓ Tested formula & cited sources Checked against independent sources · Oct 18, 2026 Private: runs in your browser

Total principal amount you are borrowing

The annual percentage rate on your loan

Duration of the loan. Enter years or months using the toggle above.

Additional amount you plan to pay each month to reduce principal faster

Results

Monthly Payment

$500.95

Total Interest Paid
$5,057
Total Cost of Loan (Principal + Interest)
$30,057
Interest as % of Total Cost
16.8%
Loan Term
5 years (60 payments)

The formula

M = P × [r(1+r)^n] / [(1+r)^n − 1]

M
Monthly Payment
Principal & Term
Loan Amount & Duration
r
Monthly Rate

Worked example — Loan Amount 25000, Annual Interest Rate (APR) 7.5 %, Loan Term 5, Extra Monthly Payment (Optional) 0

Monthly Payment = $500.95

Full explanation ↓

How Repayment Calculator Works

M = P × [r(1+r)^n] / [(1+r)^n − 1]

The monthly payment is calculated using the standard loan amortization formula. Each payment is split between interest charged on the remaining balance and principal repayment, with the proportion shifting over time. Early in the loan term, payments are mostly interest. Later, they become mostly principal. This is the fundamental mechanism of amortization, and understanding it helps you see why extra payments are so effective at reducing total interest.

M
Monthly Payment — The fixed amount paid each month toward principal and interest. This amount stays constant over the life of a standard amortizing loan.
Principal & Term
Loan Amount & Duration — The principal (P) is the total borrowed; the term (n) is the duration in months. A 5-year $25,000 loan has P=$25,000 and n=60. Together these determine the payment and total interest cost.
r
Monthly Rate — Annual interest rate divided by 12. Even small differences in r compound dramatically over the life of a loan.
Amortization means early payments are mostly interest; extra principal payments early on save the most interest

Understanding the Result

Every loan payment is split between interest charged on the remaining balance and principal repayment. Early payments are mostly interest — later payments are mostly principal. This is called amortization. For example, on a $25,000 loan at 7% over 5 years, your first payment is about $146 interest and $349 principal. By the final payment, it is about $3 interest and $492 principal. Even small extra payments go directly to principal reduction, which means less interest accrues on future balances.

The schedule below shows exactly how each payment is applied month by month, and the downloadable CSV lets you import the data into your own spreadsheet or financial planner. The "extra payment" feature shows you the impact of even modest additional amounts: $25 extra per month on that same loan saves about $277 in interest and shortens the term by 3 months — and the effect grows much larger on bigger, longer-term loans like mortgages.

How to Use

  1. Enter the total loan amount (principal) and the annual interest rate (APR) from your lender.
  2. Choose whether your loan term is in years or months, and optionally enter an extra monthly payment to see how much time and interest you can save.
  3. Scroll down for the full amortization schedule showing every payment month by month.

Frequently Asked Questions

How does an extra payment save me money?
Extra payments go directly to reducing the principal balance. Since interest is calculated on the remaining balance, a lower principal means less interest accrues each month. On a $25,000 loan at 7% over 5 years, $25 extra per month saves about $277 in interest and shaves 3 months off the term; on a larger, longer-term loan like a mortgage, the same size extra payment can save thousands. The earlier you start making extra payments, the greater the impact because you reduce the principal before more interest has a chance to accrue on it.
Should I make extra payments or invest instead?
If your loan APR exceeds your expected investment returns (which it almost certainly does for most consumer debt), paying down the loan is the better financial move. A guaranteed 7% return by avoiding interest is a risk-free return that is hard to match once taxes and market volatility are considered, even though the stock market's long-run nominal average is around 10%. The one exception is if you don't have an emergency fund — prioritize 3-6 months of expenses first before making extra loan payments. Another exception: if your loan has a very low rate (e.g., 3% mortgage), investing may yield higher returns.
Are there prepayment penalties on personal loans?
Most personal loans do not have prepayment penalties, unlike some mortgages. However, always check your loan agreement. Some states restrict them and federal rules limit them on most residential mortgages, but terms differ by lender and loan type. When in doubt, ask your lender specifically: "Is there any penalty for paying off this loan early?" If there is a penalty, calculate whether the interest savings still exceed the penalty amount.

Common Uses

  • •Calculate the monthly payment for any loan amount, interest rate, and term to see the full amortization schedule month by month.
  • •See how extra payments reduce your total loan cost and shorten the repayment period for mortgages, auto loans, or personal loans.
  • •Understand the true cost of borrowing by viewing how much of each payment goes toward interest versus principal over time.

Sources

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Cite this calculator

TheCalcUniverse. "Repayment Calculator — Amortization & Extra Payments." TheCalcUniverse, 2026, https://thecalcuniverse.com/finance/repayment-calculator/. Accessed October 25, 2026.

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