Calculator

See how much interest you'd save by paying more

See exactly how many years — and how many thousands in interest — you'd save by adding even $100/month to your mortgage. Works for extras, biweekly, or lump-sum payments.

Your loan

Remaining term30 years

Extra payments

Your savings

Base P&I: $2,335
Interest saved
$115,871
Time saved
6.2 yrs
New payoff
286 mo
Baseline interest
$480,583
New interest
$364,712
Months saved
74 mo

Rates, taxes, and insurance can change over time — assumes your extras are applied to principal each month. Estimates only based on national averages. Always confirm with a licensed lender.

Biweekly vs monthly — what is actually happening

A biweekly schedule means 26 half-payments per year. That is 13 full payments instead of 12 — one extra payment entirely.

Standard monthly
12 payments / yr
  • Simplest to budget
  • No fee programs
  • Add extras anytime
Biweekly equivalent
13 payments / yr
  • Shaves 4-6 years on 30-yr loans
  • Same math as 1/12 extra each month
  • Skip 3rd-party fee programs
Why extras work so hard

You beat the interest clock

On a 30-year loan, the first month of interest alone can be thousands of dollars. Every dollar you can shift to principal permanently avoids interest on that dollar for every month remaining in the loan.

That is why early extra payments are worth so much more than late ones — the earlier they happen, the longer they avoid compounding interest.

How to use this calculator

Three strategies, one view

Monthly extras: the most flexible — stop anytime your budget tightens.

Biweekly equivalent: toggles on 1 extra monthly payment per year.

Lump sum: apply a bonus, tax refund, or windfall to the balance.

You can combine all three to see the compounded effect.

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Keep planning with our other free calculators and guides.

Frequently asked questions