The short answer
Extra mortgage payments save far more than they cost because each dollar stops interest from building on that part of the balance for the rest of the loan. On a $400,000, 30-year mortgage at 6.5%, an extra $100 a month saves about $63,900. An extra $500 a month saves about $205,600 and pays the house off more than ten years early. The earlier you start, the more each dollar saves.
Why small extra payments matter so much
Most people assume an extra $100 on a $400,000 loan is a rounding error. It feels like throwing a cup of water at a house fire.
It isn't, and the reason is time. That $100 goes straight to principal. The bank can no longer charge interest on it. Not this month, not next month, not for the next 25 years. The savings compound quietly in the background, month after month, for as long as the loan would have run.
Small and early beats large and late. That idea is the whole game, and it's the first thing we show people in a free payoff projection.
What each extra amount saves
Here is a $400,000, 30-year mortgage at 6.5%, with a regular payment of $2,528. Without extra payments, it takes 30 years and costs $510,178 in interest.
| Extra per month | Paid off in | Time saved | Interest saved |
|---|---|---|---|
| $50 | 28 years, 4 months | 1 year, 8 months | $34,465 |
| $100 | 26 years, 10 months | 3 years, 2 months | $63,917 |
| $200 | 24 years, 5 months | 5 years, 7 months | $111,892 |
| $300 | 22 years, 5 months | 7 years, 7 months | $149,581 |
| $500 | 19 years, 5 months | 10 years, 7 months | $205,557 |
| $750 | 16 years, 9 months | 13 years, 3 months | $253,854 |
| $1,000 | 14 years, 9 months | 15 years, 3 months | $288,297 |
Look at the $50 row. Fifty dollars a month is $18,000 over 30 years if you paid it the whole time. It saves more than $34,000. The return is that good because you're avoiding interest, and the loan charges plenty of it.
Starting early beats starting big
Here's the same extra $200 a month, started at three different points in the loan:
| Start the extra $200 in | Paid off in | Interest saved |
|---|---|---|
| Year 1 | 24 years, 5 months | $111,892 |
| Year 6 | 26 years | $71,472 |
| Year 11 | 27 years, 4 months | $41,859 |
Same money each month. Waiting ten years cuts the savings by almost two thirds.
This is a direct result of the 85% problem. In the early years, most of every payment goes to interest because the balance is at its highest. Extra principal paid then cuts the balance when it's costing you the most. We explain why in how mortgage amortization works.
If you've already been in your home for a while, don't let this table discourage you. The best time to start was year one. The second best time is this month.
How to make extra payments the right way
The math only works if the money reaches principal. Three steps make sure it does.
Label it. Most servicer websites have a box for "additional principal." Use it every time. If you mail a check, write "apply to principal only" in the memo line.
Check your statement. Look at the next statement and confirm the principal balance dropped by the extra amount. Some servicers hold extra money as a credit toward next month's payment, which saves you nothing.
Automate it. An extra payment that depends on remembering will eventually be forgotten. Set it up once and let it run.
These sound basic. They're also the most common place people lose money, which is why they lead our list of mortgage payoff mistakes.
Other ways to get the same result
Monthly extra payments aren't the only way to send more money to principal. If your income arrives in lumps, one larger payment a year can work nearly as well. On our example loan, one extra full payment a year saves about $112,000, almost exactly what $200 a month saves. See one extra mortgage payment a year for the details.
If you're paid every two weeks, biweekly mortgage payments build the extra money into your schedule automatically.
For all eight approaches compared, start with how to pay off your mortgage faster.
When extra payments aren't the right move
Extra mortgage payments are a good use of money, but rarely the first one.
If you're carrying credit card balances at 20% or more, pay those off first. Every dollar there saves three times what it would on a 6.5% mortgage. The Zero Debt Method is built for households juggling several balances at once.
And keep an emergency fund of three to six months of expenses before sending extra to your lender. Money paid into your mortgage is hard to get back when you need it.
There's another way to shorten the loan
Every number on this page depends on finding extra money each month. Ridgewell's Mortgage Accelerator Program takes a different approach. It is designed to change how your mortgage is structured so the money you already earn does more of the work. For qualifying households, it is designed to pay off a home in as little as 5 to 7 years.
Payoff timelines are illustrations for qualifying households and are not guaranteed.
Where to start
Pick an amount you won't miss. For many people that's $100. Set it up as an automatic principal payment this week, then raise it every time your income goes up.
If you'd like to know exactly how far your own loan could move, get a free payoff projection built from your real balance, rate, and budget.
All examples assume a $400,000, 30-year fixed mortgage at 6.5%, principal and interest only, with figures rounded.
