United States · Federal·Updated for 2026·Figures in USD · fixed-rate loans
Mortgage Extra Payment Calculator
See what paying a little more does to your mortgage. Add an extra amount each month, once a year or as a one-time payment, and get the interest you save, how much sooner the loan ends, and the new schedule.
Your loan
$
Your current balance, or the loan amount for a new loan
%
e.g. 30 for a new 30-year loan, 24.5 if you are 5½ years in
years
Extra toward principal
$
$
For example a bonus or tax refund, paid every 12th month
$
Enter your balance, rate and years left, then an extra amount. What it saves appears here as you type.
Calculating
Show the mathSee how this was worked outHide
A fixed-rate loan. Each extra goes straight to principal, so your required payment stays the same and the loan ends sooner. Interest is worked out monthly on the balance and rounded to the cent.
Last reviewed October 19, 2026. The math is the standard fixed-rate schedule; the prepayment and servicer rules are from the Consumer Financial Protection Bureau.
What an extra payment saves
A $300,000 loan at 6.5% over 30 years has a $1,896.20 payment and $382,636.71 of interest. Paying more each month:
Extra each month
Paid off in
Time saved
Interest saved
$100
26 years
4 years
$60,995.81
$200
23 years 1 month
6 years 11 months
$103,450.19
$500
17 years 6 months
12 years 6 months
$179,761.68
Why extra payments save so much
Each month's interest is worked out on the balance. An extra payment goes straight to principal, so every later month charges interest on a smaller balance, and more of your regular payment goes to principal too. That is why the saving is bigger the earlier you pay. A one-time $10,000 on the same loan, paid with the first payment, saves $53,602.60 and 2 years 9 months.
Extra payment or recast?
Extra payments keep your payment the same and end the loan sooner. A recast uses a lump sum to lower the payment instead, keeping the same end date. Use the mortgage recast calculator to compare the two.
How much does an extra $100 a month save on a mortgage?
On a $300,000 loan at 6.5% over 30 years, an extra $100 a month saves $60,995.81 in interest and pays the loan off 4 years early.
Is it better to pay extra monthly or once a year?
Paying the same total sooner saves a little more, because the balance falls earlier. Paying one extra full payment ($1,896.20) every 12th month on the same loan saves $83,986.01 and 5 years 8 months.
Do extra payments lower my monthly payment?
No. On a fixed-rate loan the required payment stays the same; the loan just ends sooner. To lower the payment with a lump sum, ask your servicer about a recast.
Is there a penalty for paying extra?
Check your loan for a prepayment penalty before paying extra. Lenders can only charge one if you agreed to it at closing, and it usually applies to paying off the whole loan in the first three to five years (CFPB).
How do I make sure an extra payment goes to principal?
Tell your servicer an extra payment is for principal. Federal rules require servicers to credit payments correctly (CFPB).
Can paying extra remove PMI sooner?
Yes. You can ask to cancel PMI once your balance reaches 80% of the home’s original value, and extra principal payments get you there sooner (CFPB).
