Loan Amortization Schedule with Extra Payments
Extra payments shorten the schedule and cut interest.
Extra-payment scenarios run locally — no account neededYour payment breakdown appears here
Fill in the loan details and press Calculate — the monthly payment, total interest and schedule will render right on this page, with nothing sent to any server.
How to use
Adding a little extra to your monthly payment shortens the loan and cuts the interest you pay. This calculator models the two common ways to pay extra: a fixed additional amount every month, or a single lump paid directly toward principal.
How to use
- Enter your current balance, APR and months remaining.
- Type the extra amount you can add each month.
- Press Calculate to see the new term and the interest saved.
- For a lump-sum prepayment, use the Lump prepay field instead.
Example
A $20,000 loan at 6.5% with 60 months left has a normal payment of about $391. Add $150 extra each month and the loan clears in roughly 42 months instead of 60, saving about $1,100 of interest. Adding $300 instead clears it in about 32 months and saves close to $1,670.
Formula
The amortization loop re-runs with payment = regular payment + extra until the balance hits zero. The shorter the resulting term, the more interest you keep.
Extra monthly payments
Adding a fixed amount every month compounds quietly: the payment stays predictable and the principal falls faster each period. The table above shows the effect at three levels on a 5-year loan.
One-time principal payment
A single lump toward principal today reduces the balance immediately, so it saves more interest than the same total spread over later months.
A lump prepayment today reduces the balance immediately, so it saves more interest than the same total spread over later months. On the example above, a single $2,000 lump toward principal shortens the term by about 6 months and saves roughly $700 — you get the benefit instantly instead of over the remaining years.
Savings at a glance
| Extra per month | New term | Interest saved |
|---|---|---|
| $100 | 47 months | about $820 |
| $150 | 42 months | about $1,100 |
| $300 | 32 months | about $1,670 |
Even small amounts help because the extra goes straight to principal, and principal is what interest is charged on.
FAQ
Should extra payments go to principal?
Yes — extra paid usually reduces principal directly, which is what saves the interest. Confirm with your lender that there is no prepayment penalty.
Lump or monthly — which wins?
A lump now saves more total interest because it cuts the balance earlier. Monthly extra is easier to sustain from cash flow.
Is this the same as the prepayment tool?
Yes — this page covers both modes in one place: monthly extra and one-time principal.
Does it work for mortgages?
Yes, and the dollar savings are largest on long mortgage terms.
Reviewed by the LoanMath editorial team