Loan Repayment Calculator

1. Enter the amount you are borrowing in Loan amount. For a $300,000 loan, enter 300,000.
2. Enter the agreed rate in Annual interest rate as a percentage. For 6.5% per year, enter 6.5.
3. Enter the Loan term in months. A 30-year loan is 360 months, and a 15-year loan is 180 months.
4. Select Calculate to see the estimated monthly payment, total payment, total interest and the schedule for every month.

In a fixed-payment amortizing loan, the amount you pay each month stays the same from the first payment to the last, while the split inside that payment changes. Interest is charged only on the balance you still owe, so early on the balance is large and most of the payment goes to interest. As the balance falls, the interest part shrinks and the principal part grows by the same amount. The schedule above shows that shift month by month. This is the structure used by many mortgages, auto loans and personal loans, but the calculator is not limited to any one product: it works for any fixed-rate loan repaid in equal monthly instalments.

The monthly payment comes from this formula. M = P × i × (1 + i)^n ÷ ((1 + i)^n − 1)

• M: the payment made each month
• P: the loan amount (principal)
• i: the monthly rate, that is the annual rate as a decimal divided by 12. At 6.5% per year, 0.065 ÷ 12 = 0.00541666…
• n: the total number of monthly payments

At an annual rate of 0% the denominator becomes 0 and the formula cannot be used. There is no interest in that case, so M = P ÷ n: the principal split evenly across the term.

Each month is then calculated in this order.

• Interest this month = previous balance × monthly rate
• Principal this month = monthly payment − interest this month
• New balance = previous balance − principal this month

On the final payment the remaining balance is repaid in full so that rounding does not leave a tiny amount outstanding or push the balance below zero. The last row of the schedule therefore ends at exactly 0.

Take a $300,000 loan at 6.5% per year over 360 months (30 years). The monthly rate is 0.065 ÷ 12 = 0.00541666…, so the monthly payment is about $1,896, the total paid over 360 months is about $682,600, and the total interest is about $382,600. Read the exact figures in the result panel above.

Interest in the first month is $300,000 × 0.00541666… = $1,625.00, and everything left over from the payment goes to principal — only about $271 in month one. That is why the balance barely moves at the start of a long loan.

A 0% rate works too: $12,000 repaid over 12 months at 0% is exactly $1,000 a month, with $0 of interest.

This calculator applies a standard finance formula to the values you enter and nothing else. Real loans carry the extra elements below, so a lender's figures can differ from this estimate by anything from a few cents to a noticeable amount each month.

• Lenders use their own rounding rules for each payment.
• Interest is often charged on the actual number of days between payment dates rather than a flat monthly rate.
• Property taxes, insurance, points, origination, guarantee and closing fees are not included here.
• Adjustable-rate loans are recalculated for the remaining term every time the rate changes.
• An interest-only or deferral period leaves the principal untouched for a while and increases total interest.
• Late payments are charged at a separate penalty rate, and prepayments may carry a penalty of their own.

• The annual rate you enter is divided by 12 and applied as a fixed monthly rate for the whole term.
• Only equal monthly payments are supported. Equal-principal and interest-only-then-balloon structures are not calculated.
• Adjustable rates, deferral periods, extra or early payments, late-payment interest, fees, taxes, insurance, day-count interest and lender-specific rounding are not included.
• Intermediate steps keep full decimal precision; only the amounts shown on screen are rounded for display.
• Check your loan agreement and the lender's own amortization schedule for the amounts you will actually pay.
• The result is an estimate for reference only. It is not a lending decision, a borrowing-limit assessment, or financial, legal or tax advice, and no particular loan product is recommended.
• Your inputs are calculated in this browser only and are never sent to or stored on a server.

Interest on money you borrow and returns on money you invest are the same compounding idea seen from two directions.

• Compound Interest Calculator — see how savings grow