Loan Calculator
Work out the payment and total interest on an amortized, deferred or bond-style loan.
Results update as you type.
About this calculator
A loan calculator turns a loan amount, interest rate (APR) and term into a fixed payment and shows how much interest you pay in total. For an amortized loan it uses the standard payment formula — the nominal APR is first converted to a rate per payment period using your chosen compounding frequency, then spread over the number of payments so the balance falls to zero by the end of the term. Use the tabs for the three main loan shapes: an amortized loan paid down in equal instalments, a deferred loan repaid as a single lump at maturity, and a bond-style loan where you solve the price that grows to a set amount due.
For example, a 20,000 personal loan at 7.5% APR over 5 years, paid monthly, comes to a payment of about 401 a month. Across all 60 payments you repay roughly 24,050, so the loan costs you around 4,050 in interest. Shortening the term or dropping the rate lowers that interest; paying weekly instead of monthly, or adding an extra payment each period, clears it faster still.
Use a loan calculator to compare offers on a personal, student or business loan, to work out whether a shorter term is affordable, and to see the real cost of borrowing before you sign — the total interest is often far larger than the headline rate suggests.
Frequently asked questions
What is the difference between an amortized and a deferred loan?
An amortized loan is repaid in equal periodic payments that each cover interest plus some principal, so the balance falls to zero by the end of the term. A deferred loan makes no payments during the term — interest compounds and the whole principal plus interest is due as one lump sum at maturity.
How does a bond-style loan work here?
A bond (zero-coupon) loan works backwards: you set the amount due at maturity and the rate, and the calculator solves the price you would pay today, which is that future amount discounted back at the compounding rate.
Do compounding and pay-back frequency change the payment?
Yes. The nominal APR is converted to the rate per payment period using the chosen compounding frequency, so paying weekly versus monthly, or compounding daily versus annually, shifts both the periodic payment and the total interest.
What is the difference between APR and interest rate?
The plain interest rate is the cost of borrowing the principal. APR (annual percentage rate) is meant to fold in certain fees as well, so it is usually the better number for comparing loans. This calculator treats the figure you enter as the annual rate applied to the balance.
How can I pay off a loan faster?
Add an amount in the extra-payment field, shorten the term, or pay more frequently. Any money above the scheduled payment goes straight to principal, which cuts the balance sooner and reduces the total interest you pay over the life of the loan.
Does the loan amount include interest?
No. The loan amount is the principal you actually borrow. The interest is charged on top over the term — the "total repaid" result is the principal plus all the interest, which is what leaves your pocket in the end.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/loan/curl
curl "https://calculator.free/api/v1/loan/?amount=20000&maturity_value=25000&rate=7.5&years=5&_mode=amortized"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/loan/?" + new URLSearchParams({
"amount": "20000",
"maturity_value": "25000",
"rate": "7.5",
"years": "5",
"_mode": "amortized"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.