Loan Balance Calculator - Remaining Principal

The remaining balance on an amortizing loan is not a straight-line fraction of the original principal. Early payments are mostly interest, so a borrower who is five years into a thirty-year mortgage still owes far more than a naive 25/30 split would suggest. The loan balance calculator walks the amortization forward one month at a time for the number of payments you have already made and reports the leftover principal, principal repaid, interest paid so far, and payoff progress as a percent of the original amount. Monthly interest is remaining balance times the annual rate divided by 1,200. Principal in that month is the payment minus interest, capped so the balance cannot go negative. After each payment, leftover cents under half a cent are treated as paid off to avoid phantom remainder. Principal paid is original amount minus remaining balance. Interest paid is the sum of monthly interest. Payoff progress is principal paid divided by the original amount. The term in years only caps how many payments may be entered; the payment amount you type is used as-is rather than recomputed from the term. Use the loan balance calculator when a statement looks off, when you are shopping a refinance and need today's principal, or when you want to see how little principal moved in the first year. If the monthly payment is below that month's interest, the run stops with an error because the loan would not amortize. Extra principal you already paid should be reflected either by a higher payment amount across those months or by starting from a statement principal as the original amount with payments made set to match that snapshot. The model is a fixed-rate, fully amortizing monthly loan with no origination fees, no escrow, and no missed payments. ARM resets, interest-only periods, and biweekly calendars are outside the layout. Rounding on a servicer statement can differ by a few cents from this walk-forward. Enter the contractual payment, not an amount that already includes optional extra principal, unless you actually paid that extra every month in the count you entered. Keep the note rate, original principal, and payment count consistent with the closing disclosure or the latest statement. For a payoff quote, lenders also add per-diem interest and fees this page does not include. Re-run after a recast or a lump-sum principal reduction by updating the original amount or the payment history you model.