How much does overpaying my mortgage by $250 a month save?

On a $220,000 balance at 4.8% with 22 years left, an extra $250 a month clears the mortgage about 5.3 years early and saves roughly $36,700 of interest. The exact figure scales with the rate and how early the overpayments start — run your own numbers above.

Is it better to overpay the mortgage or invest?

Overpaying is a guaranteed return equal to your mortgage rate, after tax and with zero risk. Beating 4.8% reliably after tax takes real equity risk; beating 1.5% does not. The honest comparison is your fixed rate against what you would genuinely earn, not a good year in the market.

Can I overpay my mortgage without penalty?

Usually up to a limit: most fixed-rate deals allow 10% of the outstanding balance per year before early-repayment charges apply; many trackers and standard-variable loans have no limit. The charge for exceeding it is typically 1–5% of the excess, which is why this page checks your overpayment against the allowance.

Mortgage Overpayment Calculator — Years & Interest Saved

Your details

Currency symbol display only

Remaining mortgage balance

Interest rate

% / yr

Remaining term

years

Monthly overpayment

Σ/ mo

On top of the required payment, every month.

Lender's overpayment allowance

% / yr

Most fixed deals allow 10% of the balance per year before early-repayment charges. Check yours.

Everything is calculated in your browser as you type. Nothing you enter is sent or stored, and no account is needed.

Your result

5.3 years shorter.

$36,688 kept

interest saved by the monthly overpayment

What the overpayment buys

Required monthly payment	—
Term without overpaying	—
Term with the overpayment	—
Inside the lender's allowance?	—
Interest saved	—

Three sizes of overpayment

Extra per month	Term becomes	Interest saved
—	—	—
—	—	—
—	—	—

What moves this result

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——
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Worth checking

Compare the mortgage rate with your realistic after-tax alternative. Overpaying a 4.8% mortgage is a risk-free 4.8%; if your savings pay less, the overpayment wins automatically. At very low fixed rates, investing the extra can honestly beat it.

Stay inside the annual allowance on fixed deals: beyond it, early-repayment charges of 1–5% can erase a year of savings in one letter. The allowance check above is there for exactly that.

Keep the payments flexible rather than contractual where possible: an overpayment you can pause in a hard month beats a higher required payment you can't.

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Common questions

How much does overpaying my mortgage by $250 a month save?: On a $220,000 balance at 4.8% with 22 years left, an extra $250 a month clears the mortgage about 5.3 years early and saves roughly $36,700 of interest. The exact figure scales with the rate and how early the overpayments start — run your own numbers above.
Is it better to overpay the mortgage or invest?: Overpaying is a guaranteed return equal to your mortgage rate, after tax and with zero risk. Beating 4.8% reliably after tax takes real equity risk; beating 1.5% does not. The honest comparison is your fixed rate against what you would genuinely earn, not a good year in the market.
Can I overpay my mortgage without penalty?: Usually up to a limit: most fixed-rate deals allow 10% of the outstanding balance per year before early-repayment charges apply; many trackers and standard-variable loans have no limit. The charge for exceeding it is typically 1–5% of the excess, which is why this page checks your overpayment against the allowance.

How this is calculated

Everything below is calculated from your inputs. Nothing is fetched or stored.

required = standard amortisation payment(balance, rate, term)
with     = month-by-month schedule at required + extra
saved    = total interest(required only) − total interest(with extra)

Both schedules run month by month at your rate, so the result reflects how amortisation actually behaves: overpayments early in the term save the most because they cancel principal that would have carried interest for decades.

Limitations. Rate changes at the end of a fixed period, offset accounts and one-off lump sums are outside this page (the early repayment calculator handles lump sums). The allowance check compares the year's overpayments with the stated percentage of the balance.