Mortgage Calculator

The level payment on a fully-amortising loan is P × i ÷ (1 − (1 + i)^−n), where P is the amount borrowed, i is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. The payment stays constant while its composition shifts: early payments are mostly interest, later payments are mostly principal.

Interest each month is charged on the balance still outstanding. In month one of a 30-year loan that balance is the entire principal, so interest consumes most of the payment and only a small slice reduces the debt. As the balance falls, the interest portion falls with it and the principal portion grows — which is why the amortisation curve steepens in the second half of the term.

Extra principal is applied directly to the balance, so every dollar removes that dollar plus all the interest it would have accrued for the rest of the term. On a $300,000 30-year loan at 6.5%, an extra $300 a month retires the loan roughly seven years early and reduces total interest by well over $100,000. Enter an extra amount above to see the effect on your own figures.

It calculates principal and interest only. Property taxes, homeowners insurance, private mortgage insurance, and HOA dues are typically collected alongside the payment in an escrow account and can add several hundred dollars a month. Add them separately when comparing a payment to a monthly budget.

The interest rate determines the payment. The APR folds lender fees, points, and certain closing costs into a single annualised figure, so it is usually slightly higher than the note rate and is the more comparable number across lenders. Use the note rate in this calculator, since that is what the amortisation is actually computed from.

A 15-year term carries a higher monthly payment and materially less total interest, because the balance is outstanding for half as long and shorter terms usually price at a lower rate. A 30-year term carries a lower required payment and more total interest. Run both terms above — the calculator reports the payment and lifetime interest for each so the trade-off is explicit rather than assumed.

Neither is calculated, and neither is silently replaced. A negative entry in any box is not an amount, so the calculator names the field and withholds the result — substituting $0 would report a payment, loan amount, and total interest for a loan you did not describe. A down payment at or above the home price leaves nothing to borrow, so there is no payment and no amortisation schedule to show. A blank down payment, or an entered 0, is a 0% down scenario and is calculated normally.

No. This calculator runs entirely in your browser. Nothing you type is transmitted to Equity Rank or saved anywhere, and no account is required to use it.