Extra Payment Mortgage Savings Calculator
Calculate exactly what extra payments save you.
All calculations happen locally in your browser — nothing is uploaded, stored or tracked.
Enter your loan
Amount, rate and term.
Set the extra payment
Any monthly amount.
Compare the plans
Time and interest saved.
What Does an Extra Payment Save?
Every extra mortgage payment is pure principal reduction, and every dollar of principal removed stops accruing interest for the rest of the loan. That double effect — smaller balance, shorter term — is what makes extra payments so powerful.
The calculator simulates your loan with any extra monthly amount and reports the exact time cut, interest saved and new payoff date.
How to Read the Results
Compare the "no extra" baseline with your plan: months cut from the term, dollars saved on interest, and the total extra you contributed. A $200/month extra on a typical 30-year loan can save more than $80,000 in interest.
Your data never leaves your device.
Every calculation on this site runs in your browser using vanilla JavaScript. Nothing is uploaded, stored or tracked.
- 100% local, client-side calculations
- No data stored on any server
- No tracking, no analytics, no ads scripts
- Works offline once loaded
Frequently Asked Questions
How much interest does an extra $100/month save?
On a $300k, 6.5%, 30-year loan it saves roughly $75,000 in interest and about 4 years of payments.
Is it better to make extra payments or invest?
Compare the mortgage rate with your expected after-tax investment return. There is no universal answer — this is a math comparison.
Do extra payments reduce my monthly payment?
No — they shorten the term instead, unless you request a recast. The calculator shows the term effect.
Can I stop extra payments later?
Yes — extra payments are optional in most cases; the benefit already accrued stays yours.
What is recasting?
Re-amortizing the remaining balance over the original term to lower the payment — different from extra payments, which shorten the term.