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Home loans

Extra Payment & Biweekly Calculator

See exactly how much interest you save and how many years you cut by paying extra principal — or switching to a biweekly schedule.

Inputs
$
%
$
Interest saved8 yr 7 mo sooner
$149,472
base payment (P&I)$2,179/mo
interest without extra$448,544
interest with extra$299,072
new payoff
2048
time saved
8 yr 7 mo
total interest
$299,072
Balance paydown
Standard payments With extra
-$27k$71k$168k$265k$363k2026203620462056

Why extra payments work so well

A fixed-rate payment is front-loaded with interest: early on, most of each payment covers the interest on a large balance, and only a sliver reduces principal. An extra principal payment skips that interest entirely — it permanently removes that dollar from the balance, so it never accrues interest again for the remaining years of the loan.

Because the effect compounds over decades, small extra amounts have outsized results. The chart above contrasts your standard paydown with the accelerated one; the gap between the lines is interest you keep.

interest saved = interest (baseline) − interest (with extra)

Common questions

How much do extra mortgage payments save?
Every extra dollar goes straight to principal, so it stops accruing interest for the rest of the loan. On a 30-year loan, even $100–$300 a month can save tens of thousands in interest and shave years off the term. Enter your loan above to see your exact numbers.
Are biweekly payments worth it?
Paying half your monthly amount every two weeks means 26 half-payments a year — equal to 13 monthly payments, or one extra payment annually. That single extra payment typically knocks 4–6 years off a 30-year mortgage at no real change to your budget.
Is it better to pay extra or refinance?
They solve different problems. Refinancing lowers your rate; extra payments shorten the term at your current rate. If rates have dropped meaningfully, refinance first — then apply extra payments to the new loan for the biggest effect.
Should I make extra payments or invest instead?
Compare your mortgage rate to your expected after-tax investment return. Paying down a 7% mortgage is a guaranteed 7% return; investing might beat it but isn't guaranteed. Many people split the difference. This tool shows the guaranteed side.

How we calculate this

We amortize your loan month by month, then re-run it adding your extra principal to each payment. Biweekly is modeled as its cash-flow equivalent — one extra payment per year. Planning estimates only — not financial advice.

Full methodology & sources →
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Estimates for general informational purposes only and not financial advice. Confirm your loan has no prepayment penalty and that extra payments are applied to principal. Actual figures depend on your servicer's posting rules.