Mortgage Prepayment Calculator

See how much sooner you’ll pay off your mortgage, and how much interest you’ll save, by paying extra each month or a lump sum.

Mortgage balance

What you owe now

Interest rate

Years left

Payments

Extra each payment

One-off lump sum

Paid now

Mortgage-free sooner by

2 years, 3 months

Paid off in 17 years, 9 months instead of 20 years

Interest saved: $27,827
Monthly payment with extra: $2,785.48

Interest you’ll pay$192,689
Interest saved$27,827

What this means

Every extra payment goes straight off what you owe, so you stop paying interest on it. That’s like a guaranteed return of 4.8%, your mortgage rate.

Clear debts with higher rates, like credit cards, first, and keep an emergency fund before overpaying. Check your lender’s limits on overpayments without a fee.

Next step

Compare with saving it instead

With and without overpaying

	Without	With
Monthly payment	$2,585.48	$2,785.48
Lump sum now	–	–
Time left	20 years	17 years, 9 months
Total interest	$220,516	$192,689
Total paid	$620,516	$592,689

Before you overpay

Most mortgages let you prepay a set amount each year without a penalty, often 10% to 20% of the original amount. Check your mortgage’s prepayment privileges.

Keep some savings for emergencies first. And if your savings earn more after tax than your mortgage rate, saving can beat overpaying.

$33,426$16,713$0

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PrincipalInterest

Assumptions in this estimate

Your payment stays the same, so overpaying shortens the mortgage. Some lenders lower your payment instead, which saves less interest.
Assumes the interest rate stays the same for the rest of the mortgage.
Interest compounds twice a year, as on Canadian fixed-rate mortgages.
Fees or charges for overpaying aren’t included.

Spotted a mistake? Tell us

How the calculator works

Your mortgage now: what you owe, the rate and the years left give your current payment.
Paying extra: an extra amount with every payment, a one-off lump sum, or both. Your payment stays the same, so the mortgage ends sooner.
The difference: how much sooner it’s paid off, and the interest you save.

Example

$400,000 at 4.8% with 20 years left, repaid at $2,585.48 a month:

Paying extra	Paid off in	Interest saved
Nothing	20 years	–
$200 a month	17 years, 9 months	$27,827
$500 a month	15 years, 3 months	$58,171
$10,000 lump sum	19 years, 3 months	$15,374

Last updated October 14, 2026

Frequently asked questions

How much will I save by paying $200 extra a month?

On a $400,000 mortgage at 4.8% with 20 years left, $200 extra a month clears it 2 years, 3 months sooner and saves $27,827 in interest.

Is a lump sum or extra each month better?

Both help, and the sooner money goes in, the more interest it saves. On the same mortgage, a $10,000 lump sum now clears it 9 months sooner and saves $15,374.

How much can I prepay without a penalty?

It depends on your mortgage. Most let you prepay a set amount each year, often 10% to 20% of the original amount, and raise your payments. Paying more than that can mean a prepayment penalty.

Should I pay off my mortgage or save?

Keep some savings for emergencies first. After that, if your savings earn more after tax than your mortgage rate, saving can come out ahead.