See how much time and interest you save by paying a little extra toward your mortgage.
Extra payments
The yearly amount is paid once a year, in month 12. The lump sum is applied today.
Principal and interest only. Taxes, insurance, PMI and HOA fees are not included. The payoff date assumes your next payment is due next month.
Quick answer: on a $300,000 balance at 6.5% with 30 years left, paying an extra $200 a month pays the loan off in about 23 years and 1 month instead of 30. That saves roughly $103,400 in interest and cuts 6 years and 11 months off the loan. Enter your own balance, rate and extra amount above.
Each month, your payment is split between interest and principal. Interest is charged on the balance you still owe, so a smaller balance means less interest next month. When you send extra money toward principal, that part of the balance stops generating interest for the rest of the loan. The effect compounds: your regular payment stays the same, but a larger share of it goes to principal every month, so the loan ends sooner.
This calculator keeps your required payment fixed at the amount for your current balance, rate and remaining term, then applies your extra payments on top. It also lets you add a yearly amount (paid in month 12 of each year) and a one-time lump sum applied today.
Here is a $300,000 balance at 6.5% with 30 years remaining, paying a fixed extra amount every month (principal and interest only):
| Extra per month | Paid off in | Total interest | Interest saved | Time saved |
|---|---|---|---|---|
| +$50 | 27 years 10 months | $349,052 | $33,581 | 2 years 2 months |
| +$100 | 26 years | $321,639 | $60,994 | 4 years |
| +$200 | 23 years 1 month | $279,185 | $103,448 | 6 years 11 months |
| +$300 | 20 years 10 months | $247,518 | $135,115 | 9 years 2 months |
| +$500 | 17 years 6 months | $202,874 | $179,759 | 12 years 6 months |
Small amounts matter more than most people expect. Even $100 a month trims about four years off a 30-year loan in this example.
The earlier extra money reaches your balance, the less interest it avoids. Compare these options on the same $300,000, 6.5%, 30-year loan:
| Option | Paid off in | Total interest | Interest saved |
|---|---|---|---|
| $200 every month | 23 years 1 month | $279,185 | $103,448 |
| $2,400 once a year (month 12) | 23 years 3 months | $282,963 | $99,670 |
| $10,000 one-time lump sum today | 27 years 3 months | $328,717 | $53,916 |
| $10,000 lump sum today + $200 every month | 21 years 5 months | $246,961 | $135,672 |
Paying $200 every month saves slightly more than saving the same $2,400 and paying it once a year, because the money starts reducing the balance sooner. A lump sum helps a lot early in the loan, and combining a lump sum with monthly extras saves the most.
The higher your rate, the more each extra dollar saves. The same $200 a month on a $300,000 balance with 30 years left:
| Interest rate | Interest saved | Time saved |
|---|---|---|
| 4.5% | $59,436 | 6 years 4 months |
| 6.5% | $103,448 | 6 years 11 months |
| 7.5% | $130,781 | 7 years 4 months |
Paying half your payment every two weeks results in 26 half-payments a year, which equals 13 full payments instead of 12. That is roughly the same as adding one-twelfth of your payment each month. On the loan above, one-twelfth of the payment is about $158 extra a month, which pays the loan off in about 24 years 2 months and saves roughly $87,256. Some lenders charge fees to enroll in biweekly plans, so you can often get the same result for free by adding the extra amount to your monthly payment.
Paying extra gives you a guaranteed return equal to your mortgage rate, because every dollar prepaid avoids that rate of interest. Whether it is the best use of your money depends on your situation. Things to weigh:
This calculator assumes a fixed rate. For an adjustable-rate loan, enter your current rate and remaining term for a rough estimate. Results are estimates; your servicer’s figures are the official ones.