Extra mortgage payment calculator

B(0) = Current balance − Extra payment; r = Annual rate [%] ÷ 1200; B(next month) = maximum(0, B × (1 + r) − A). A is the original constant annuity payment, r the monthly interest rate and B the balance. The extra payment is immediate; keeping the same payment shortens the term. The model compares accumulated monthly interest with and without the extra payment. Fees and contractual prepayment limits are excluded.

A is the original constant annuity payment, r the monthly interest rate and B the balance. The extra payment is immediate; keeping the same payment shortens the term. The model compares accumulated monthly interest with and without the extra payment. Fees and contractual prepayment limits are excluded. The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation. Prices, measurements and model assumptions determine how well the result represents your situation.

Yes. Calculations and PDF export work without an account or registration.

Calculations run in your browser. Results are saved locally only when you add them to My results; favourites and history are also local. Shared links contain your values. The currency tool requests the selected currencies from its rate provider without sending your amount.