Loan Payment Calculator
Monthly payment, total interest and a full amortisation schedule for any loan — plus what extra payments save, and the ability to solve backwards for the amount, rate or term.
Instant answers
Works offline once loaded
Nothing you type is sent anywhere
Full amortisation schedule
Solve for any variable
Extra-payment savings
What do you want to work out?
The nominal APR, not the monthly rate.
Only needed when solving for something else.
Paid straight off the principal.
Subtracted from the amount before interest.
Payment
—
Principal —
Interest —
Total of all payments—
Total interest—
Interest as a share of the loan
Amount financed—
Number of payments—
Paid off in—
Periodic rate—
Effective annual rate—
Balance over the life of the loan
Hover the chart to read the balance at any point.
What the extra payment buys you
Interest saved—
Paid off earlier by—
Without the extra it would cost—
Return on the extra money—
Amortisation schedule
| Year | Payments | Principal | Interest | Balance |
|---|
Instructions
How to use this calculator
Step by step
- Pick what you want to solve for. The default is the payment; you can equally ask how much you can borrow for a payment you can afford, what rate a quoted payment implies, or how long a loan will take to clear.
- The field being solved for greys out — it is the answer, so you do not fill it in.
- Enter the loan amount, the annual rate as a percentage, and the term in years and months. The rate is the nominal APR the lender quotes, not a monthly figure.
- Change the payment frequency if you are not paying monthly. Paying every two weeks makes 26 payments a year rather than 24, which is why it clears a loan noticeably faster.
- Add an extra payment amount to see what overpaying does. The savings panel appears as soon as the extra is above zero.
- Use the fees and down payment fields if the lender is rolling costs into the loan or you are putting money down — both change the amount that actually accrues interest.
- Read the schedule at the bottom. Switch it to Every payment to see exactly where each payment goes, which is the fastest way to understand why the early years feel like nothing is happening.
Good to know
- Every extra dollar goes straight against the principal, so it saves you all the future interest that dollar would have carried. Early extra payments are worth far more than late ones.
- Compare loans on total interest, not on the monthly payment. Stretching a loan from four years to six lowers the payment and raises what you pay overall.
- The APR a lender quotes includes some fees; the rate this calculator uses is whatever you enter. To compare offers properly, put each lender's APR in and add their fees to the fees box.
- Paying every two weeks rather than twice a month sneaks in one extra full payment a year. On a long loan that alone can take a year off the term.
- Check whether your loan has a prepayment penalty before you plan to overpay. They are rare on mortgages now but still common on car and personal loans.
- A zero-interest promotional loan really is just the amount divided by the term — but check what the rate becomes when the promotion ends, and whether interest is backdated.
The maths behind it
- Payment A = P · i / (1 − (1 + i)⁻ⁿ) P is the principal, i the rate per period, n the number of periods.
- Rate per period i = annual rate ÷ payments per year A 6% APR paid monthly is 0.5% per month.
- Principal from a payment P = A · (1 − (1 + i)⁻ⁿ) / i How much a given payment can support.
- Number of payments n = −ln(1 − P·i/A) / ln(1 + i) Undefined when A ≤ P·i — the payment never covers the interest.
- Interest in a period interest = balance × i Everything left over reduces the balance.
- Effective annual rate EAR = (1 + i)^periods − 1 What the nominal rate really costs once compounding is counted.
Why is so much of my early payment interest?
Because interest is charged on the balance, and at the start the balance is the whole loan. On a 30-year mortgage at 7%, the first payment is roughly 80% interest. That ratio flips slowly and then quickly — by the last few years almost the entire payment is principal. Switch the schedule to Every payment to watch it happen.
What is the difference between the interest rate and the APR?
The interest rate is what accrues on the balance. The APR folds in origination fees, points and some closing costs, expressed as an annualised rate, so it is the better number for comparing two offers. If you enter an APR into this calculator, leave the fees box at zero — otherwise you count them twice.
Does paying extra actually save that much?
Yes, and the effect is larger than most people expect because the saving compounds. An extra $100 a month on a $28,000 loan at 6.9% over five years saves several hundred dollars and clears it most of a year early. The savings panel on this page shows the return on the extra money as a percentage, which is the fairest way to compare overpaying against investing it instead.
What happens if my payment is too small?
If the payment does not cover the interest accruing each period, the balance grows rather than shrinks — negative amortisation. The loan is never repaid at that payment, no matter how long you run it. This calculator detects that case and tells you rather than showing a nonsense term.
Is biweekly really better than monthly?
Usually, for two reasons: 26 biweekly payments equal 13 monthly ones rather than 12, and interest accrues on a lower average balance. But it only helps if the lender applies each payment when it arrives rather than holding it. Ask before signing up for a paid biweekly service — you can get the same result free by paying an extra 1/12th each month.
Can I use this for a mortgage?
The amortisation is identical, so yes for the loan itself. But a mortgage payment also carries property tax, insurance and sometimes HOA fees, which are not interest and do not amortise. Use the mortgage calculator on this site for the full PITI picture.