Calculate the installment needed to clear a balance in a fixed time, or enter an installment to estimate the payoff time. Compounding and payment schedules are separate so the page can model monthly, weekly, biweekly, quarterly, and other contracts.
How to use this calculator
- Choose Fixed Time to find a payment, or Installment to find the repayment length.
- Enter the current loan balance and nominal annual interest rate.
- Choose the compounding and pay-back frequencies separately.
- Enter your target term or the amount you pay each period, then review the schedule.
The installment follows the pay-back frequency: a weekly installment is a weekly amount, not a monthly one. Match that setting before comparing scenarios.
Understanding your results
| Result | What it tells you |
|---|---|
| Payment | The amount needed each payment period in the fixed-time scenario. |
| Repayment length | How long the selected installment takes to clear the balance. |
| Total interest | Interest paid over the modeled repayment period. |
| Amortization table | The interest, principal repayment, and remaining balance as the loan is repaid. |
A smaller payment can extend repayment and increase interest. If a payment does not cover the period's interest, the calculator reports an error because that payment cannot clear the balance. The last payment may be smaller than the regular installment.
For extra monthly, annual, or one-time mortgage payments, use the Mortgage Payoff Calculator. Use the Loan Calculator for deferred-payment and bond scenarios.
Examples
Five-year monthly repayment
A $10,000 balance at a 10% nominal rate compounded monthly requires about $212.47 per month for 60 months. Total payments are about $12,748.23, including about $2,748.23 of interest.
Check a fixed installment
If the installment is no larger than the interest generated in one payment period, the balance never declines and the calculator rejects the scenario. Increase the installment or correct the rate and frequency inputs.
Formula
The nominal annual rate is converted through the selected compounding convention to an effective annual rate, then to a rate r for each payment period. For principal P and n level payments:
payment = P × r / (1 − (1 + r)^−n)
The fixed-installment mode rearranges the same relationship to estimate the number of payments. At a zero rate, payment is simply principal divided by payment count.
Match the contract
Use the balance, nominal rate, compounding frequency, and payment frequency stated in the agreement. This general model excludes fees, insurance, penalties, taxes, changing rates, irregular dates, and extra payments. Its rate is a mathematical nominal rate, not a fee-inclusive consumer-credit disclosure APR.