Skip to content
CalcTortoise

Loan Overpayment Calculator

Find out how overpayments — every month, once a year or a single lump sum — shorten a loan and reduce the interest you pay.

Written by the CalcTortoise editorial team · How we work

years

Paid on top of every monthly instalment.

For example from a bonus, paid with the last instalment of each year.

After each overpayment

Interest saved

$57,646

Loan cleared in
19 years 8 months (5 years 4 months sooner)
Monthly instalment (unchanged)
$1,611
Interest without overpaying
$233,226
Interest with overpayments
$175,580
Total overpaid
$47,000

Illustration only, not investment, tax or legal advice.

What you repay with overpayments
  • Principal$250,000 (58.7%)
  • Interest$175,580 (41.3%)
Balance outstanding, with and without overpayingWithout overpayingWith overpayments

Repayment schedule with overpayments

YearInstalmentsOverpaidPrincipalInterestBalance outstanding
$19,329$2,400$6,917$14,812$243,083
$19,329$2,400$7,344$14,385$235,739
$19,329$2,400$7,797$13,932$227,942
$19,329$2,400$8,278$13,451$219,664
$19,329$2,400$8,788$12,941$210,876
$19,329$2,400$9,330$12,399$201,546
$19,329$2,400$9,906$11,823$191,640
$19,329$2,400$10,517$11,212$181,123
$19,329$2,400$11,165$10,564$169,958
$19,329$2,400$11,854$9,875$158,104
$19,329$2,400$12,585$9,144$145,519
$19,329$2,400$13,361$8,368$132,158
$19,329$2,400$14,185$7,544$117,972
$19,329$2,400$15,060$6,669$102,912
$19,329$2,400$15,989$5,740$86,922
$19,329$2,400$16,975$4,754$69,947
$19,329$2,400$18,022$3,707$51,924
$19,329$2,400$19,134$2,595$32,790
$19,329$2,400$20,314$1,415$12,476
$11,328$1,400$12,476$252$0

Tap a year to see its months.

How to use this calculator

  1. Enter the loan amount, interest rate and term.
  2. Add an overpayment each month, each year, or once.
  3. Choose whether to finish sooner or lower the instalment.

Frequently asked questions

How much does overpaying save?

On $250,000 at 6% over 25 years, an extra $200 a month saves $57,646 in interest and clears the loan 5 years 4 months early.

Is it better to shorten the term or lower the instalment?

Keeping the instalment and finishing early saves more interest: here $57,646, against $26,216 if each overpayment lowers the instalment instead.

Will my lender charge for overpaying?

Some loans allow a certain amount of overpayment each year free of charge and apply a fee above it; others charge nothing. Check your loan terms before overpaying.

Sources and method

The reducing-balance loan formula, run month by month with your extra payments taken off the balance.

No outside data is used. The numbers you type in are the only inputs.

Page and formula last reviewed . How we calculate · Editorial policy · Corrections and change log

Related calculators

Last updated 9 October 2026. For information only — not financial advice. Check the final figures with your lender or bank.