Biweekly Mortgage Payment CalculatorFree online financial calculator — instant results, no sign-up

P = M / 2; i = (r / 100) / 26; B_0 = B. For each period k: J_k = i × B_(k−1); A_k = min(P, B_(k−1) + J_k); B_k = B_(k−1) + J_k − A_k. Continue until B_N = 0. Total interest I = Σ J_k = Σ A_k − B, for k = 1 through N. For i > 0 and P > iB, the payment count can also be written as N = ceil[−ln(1 − iB/P) / ln(1 + i)]. With the default inputs, P = 1600 / 2 = $800.00 and i = 0.06 / 26, giving N = 555 and I = $193,236.97.

• BStarting mortgage balance in dollars.
• MScheduled monthly principal-and-interest payment in dollars.
• rNominal annual interest rate entered as a percentage.
• PRegular biweekly payment in dollars, equal to half the monthly scheduled payment.
• iInterest rate per biweekly period, expressed as a decimal.
• kBiweekly period number, starting at 1.
• B_kRemaining principal balance after payment k; B_0 is the starting balance.
• J_kInterest charged during biweekly period k, in dollars.
• A_kActual payment in period k, capped at the amount needed to clear the balance and that period's interest.
• NWhole number of biweekly payments required, including any smaller final payment.
• ITotal interest paid over the modeled repayment schedule, in dollars.
• ln, ceil, min, ΣNatural logarithm, rounding up to the next integer, selecting the smaller value, and summing across payment periods, respectively.

Halve the monthly scheduled payment and divide the annual percentage rate by 100 and then by 26. Starting with the entered balance, calculate one period's interest, add it to the balance, and subtract the biweekly payment. Repeat until the debt is cleared, reducing the final payment when less than the regular amount is owed. Count all payments and sum the interest, retaining calculation precision before displaying dollar totals to cents. At a positive rate, the regular payment must exceed the first period's interest for the balance to amortize; at a zero rate, the payment count is ceil(B/P) and total interest is zero.

These are the calculator's starting values and the results it actually produces for them.

1. 1Enter the outstanding mortgage principal in Balance ($); the default is 250000.
2. 2Enter the nominal annual interest rate in Annual rate (%); the default is 6.
3. 3Enter your monthly principal-and-interest payment in Monthly scheduled payment ($); the default is 1600, excluding escrow and fees.
4. 4Run the calculation and review the biweekly payment, payment count, and total interest.
5. 5For the default inputs, confirm the results of $800.00, 555 payments, and $193,236.97, then check with your servicer whether it applies biweekly payments as this model assumes.

Further reading

• CFPB