Repayment Calculator
Calculate the periodic repayment installment for a fixed-rate balance, given the principal, annual interest rate, repayment term, and frequency.
How It's Calculated
Formula
\text{Repayment} = \dfrac{P \times r \times (1 + r)^n}{(1 + r)^n - 1}This calculator answers a simple question: what regular payment repays a given balance, at a fixed annual rate, over a chosen term? Enter the principal, the annual fixed interest rate, how many years you have to repay it, and how often you'll make repayments, and it returns the periodic installment. The number of payments is derived automatically from your term and frequency — if you already know the exact number of payments instead of a term in years, use Payment Calculator, which takes that number directly. This calculator computes a fixed regular installment only — it does not model extra payments or payoff acceleration; for that, see Mortgage Payoff Calculator.
Worked Examples
Monthly repayment: $20,000 principal, 7.5% annual rate, 5-year term
- paymentsPerYear = 12 (monthly), so n = 5 × 12 = 60 payments
- periodicRate r = 0.075 / 12 = 0.00625
- Repayment = 20000 × 0.00625 × (1.00625)^60 / ((1.00625)^60 − 1) ≈ $400.76
Biweekly repayment: $15,000 principal, 6% annual rate, 3-year term
- paymentsPerYear = 26 (biweekly), so n = 3 × 26 = 78 payments
- periodicRate r = 0.06 / 26 ≈ 0.0023077
- Repayment = 15000 × r × (1 + r)^78 / ((1 + r)^78 − 1) ≈ $210.36
Frequently Asked Questions
How is this different from Payment Calculator?
This calculator asks for a repayment term in years and derives the number of payments for you. Payment Calculator instead asks for the exact number of payments directly. Use whichever matches what you actually know — a term in years, or an exact payment count.
Does this account for extra payments or early payoff?
No — this calculator computes a single fixed regular installment for the full term as scheduled. For modeling extra payments and how they shorten a payoff, see Mortgage Payoff Calculator.
Why does my biweekly repayment look smaller than half my monthly repayment would be?
A biweekly schedule makes 26 payments a year, not 24 — there are slightly more than 52 weeks in a year, so 26 fortnights. Making more, smaller payments more often also pays down principal faster, so the biweekly installment ends up smaller than simply halving the monthly figure.
What happens if I enter a 0% interest rate?
The repayment becomes a straight-line division of the principal across the number of payments, with $0 total interest — a valid boundary case, not an error.