Extra Mortgage Payment Calculator
Every extra dollar comes straight off the balance, and then stops earning interest for the rest of the loan. That is why small amounts do so much. One warning: tell your lender it is for principal only, or many will just credit it towards next month and you gain nothing.
You would finish
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- Interest saved
- $0
- Your normal payment
- $0
- New total payment
- $0
- Paid off in
- -
- Return on every extra dollar
- $0
Where the money goes
The green block is interest saved and it stays yours. The orange is your normal payment and it does not come back.
Move it and watch
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at {v} for what you still owe
And what you can change
Why your own figure may differ
What each amount buys you
Pick something you can keep up every month. A smaller amount you sustain beats a larger one you abandon.
| Extra each month | Paid off in | Sooner by | Interest saved |
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Extra mortgage payments: real examples
Three amounts worth seeing in numbers. Click any card to load it.
- A small amount
$100 a month on a $300,000 mortgage
Less than most people spend on coffee.
It still takes years off the loan and saves a large sum, because every dollar stops earning interest for decades.
Load this scenario in the calculator → - A round number
Rounding the payment up to $2,000
A payment of $1,799 rounded up.
A little over $200 a month makes a serious difference. Rounding up is the easiest overpayment to stick to.
Load this scenario in the calculator → - The biweekly trick
One extra payment a year
What biweekly schemes actually do, without the fee.
Dividing one payment by twelve and adding it each month gives the same result - and costs nothing to arrange.
Load this scenario in the calculator →
Common questions about extra mortgage payments
How much does paying extra really save?
Far more than people expect. Every extra dollar comes straight off the balance, and then stops earning interest for the whole remaining life of the loan. On a 30-year mortgage a modest amount each month often cuts years off and saves tens of thousands.
Do I need to tell the lender it is for principal?
Yes, and this catches people out. Send extra money without saying so and many servicers will simply credit it towards next month, which gains you nothing at all. Use the principal-only option online, or ring them. Then check the next statement to be sure it was applied properly.
Is it better than investing?
It depends on your rate. Paying down a mortgage is a guaranteed return equal to that rate, and guaranteed returns are rare. Above roughly 6% it is hard to beat. Below about 4% investing has historically done better, though not with any certainty. This gives you the guaranteed number to weigh against.
Should I pay extra or build savings first?
Savings first, almost always. Money in a mortgage is very hard to get back out - you cannot ring the bank and ask for last year overpayments when the boiler breaks. Build a cushion you can actually reach, then overpay with what is left.
Is one big payment better than a bit each month?
Earlier is always better, because the money has longer to stop earning interest. A lump sum now beats the same amount spread over a year. But consistency usually wins in practice, because a regular amount you can sustain beats a big one you only manage once.
What about biweekly payments?
Paying half your mortgage every two weeks means 26 half-payments a year, which is 13 full ones instead of 12. It is really just one extra payment a year dressed up. You can get the same effect by dividing one payment by twelve and adding it monthly - without paying anyone a fee to arrange it.