How Much Do You Save Paying Extra on Your Mortgage?

Paying a little extra toward your mortgage feels almost too small to matter. It isn’t. Because of how amortization front-loads interest, even modest extra principal payments compound into surprisingly large savings. This guide shows how the numbers scale and how to find your own. Use the Extra Payment Calculator to see your exact savings.

Why extra payments punch above their weight

Every regular mortgage payment splits between interest and principal. Early in the loan, most of your payment is interest because the balance is large. An extra payment, by contrast, goes 100% to principal. That does two things at once:

1. It immediately reduces the balance that all future interest is calculated on.
2. It removes months from the end of your loan — months that would otherwise still be charging interest.

That one-two effect is why a small extra payment saves far more than its face value.

How the savings scale

Consider a $300,000 loan at 6.5% over 30 years (payment ≈ $1,896). Adding a fixed amount each month roughly produces:

• +$100/month: pays off several years early and saves a large five-figure sum in interest.
• +$250/month: pays off many years early with even larger interest savings.
• +$500/month: can cut close to a decade off the loan.

The precise figures depend on your rate and remaining term — the higher your rate, the more each extra dollar saves. Plug in your real numbers with the Extra Payment Calculator.

Timing matters: earlier is better

Because interest is front-loaded, the same extra payment saves more the earlier you make it. An extra $5,000 in year 2 eliminates many years of future interest; the same $5,000 in year 28 saves comparatively little, since there’s barely any interest left to avoid. If you’re going to prepay, starting early maximizes the benefit.

Lump sum vs. monthly extra

Both work; they just fit different situations:

• Monthly extra is a habit — automatic, gradual, and easy to budget. Great if your savings come from income.
• Lump sum (bonus, tax refund, inheritance) delivers a big one-time balance cut. Great when windfalls arrive.

You can combine them. The Extra Payment Calculator lets you model a lump sum and a recurring monthly extra together.

Important: extra payments don’t lower your payment

A common surprise: prepaying does not reduce your required monthly payment. It shortens the term and cuts total interest, but the monthly amount stays the same until the loan is gone. If your goal is a lower payment rather than a faster payoff, you want a recast or a refinance instead. See recast vs. extra payment for the trade-off.

Make sure the extra hits principal

When you send extra money, specify that it should be applied to principal, not held as a prepayment of your next scheduled payment. Most servicers have a dedicated “additional principal” field online; if in doubt, confirm in writing. Also verify there’s no prepayment penalty (rare on modern conforming loans, but worth a check).

Should you prepay at all?

Prepaying earns a guaranteed return equal to your mortgage rate — excellent if your rate is high. But first make sure you have an emergency fund, no high-interest debt, and your employer 401(k) match captured. If your rate is low, investing the money might build more wealth, though without the guarantee. Weigh all of this in the Decision Engine, and read pay off mortgage or invest.

The short answer

Extra principal payments save far more than their size suggests because they attack principal directly and erase the interest-heavy tail of your loan. Even $100/month can save tens of thousands and shave years off the term — and the earlier you start, the better. Calculate your exact savings in the Extra Payment Calculator.

Ballpark figures, not advice. Your exact numbers live with your lender — start there before you commit.

Run the numbers in our calculator →

Frequently asked questions

Does paying $100 extra a month really make a difference?

Yes — surprisingly so. On a typical 30-year loan, an extra $100/month can save tens of thousands in interest and shave several years off the term, because every extra dollar attacks principal directly.

When does an extra payment save the most?

Early in the loan, when your balance — and therefore your interest — is highest. The same extra dollar applied in year 2 saves far more than in year 25.

Will extra payments lower my monthly payment?

No. Extra principal payments shorten your term and cut total interest, but your required monthly payment stays the same. To lower the payment instead, you'd need a recast or refinance.