How much sooner, and how much saved.
| # | Payment | Principal | Interest | Balance |
|---|
A fixed-rate loan splits every payment between interest and principal. The interest slice is whatever the balance you still owe costs for that month; whatever is left of the payment reduces the balance. Because interest is always charged on the current balance, a dollar of principal removed today is a dollar that never gets charged interest again for the rest of the term. That is the entire mechanism behind early payoff. Nothing clever is happening: the loan simply runs out of balance sooner.
To use the calculator above, enter the loan amount, the APR from your paperwork, and the remaining term, then put a number in Extra payment /mo. The payoff date, total interest, and the amortization schedule all update as you type, so you can see the effect of $25 a month as easily as $500.
For scale, take a $25,000 loan at 6.5% over 5 years. The scheduled payment is $489.15 and the loan costs $4,349.22 in interest if you never pay a cent more than required. Add $100 a month and it is gone 11 months sooner, with $865.44 less interest paid. Add $200 a month and it is gone 19 months sooner, saving $1,439.13.
Same loan, six different extra payments. Every figure is computed with the amortization math the calculator uses, so you can reproduce any row above by typing the numbers in.
| Extra per month | Paid off in | Total interest | Interest saved | Time saved |
|---|---|---|---|---|
| $0 | 5 years | $4,349.22 | 0 | 0 |
| $50 | 4 years 6 months | $3,867.77 | $481.45 | 6 months |
| $100 | 4 years 1 month | $3,483.78 | $865.44 | 11 months |
| $200 | 3 years 5 months | $2,910.10 | $1,439.13 | 19 months |
| $300 | 2 years 11 months | $2,501.48 | $1,847.75 | 25 months |
| $500 | 2 years 4 months | $1,958.73 | $2,390.49 | 32 months |
Two patterns are worth noticing. First, the early dollars work hardest: the jump from nothing to $50 a month saves $481.45, while the jump from $300 to $500 saves only $542.75 more. Second, the savings curve flattens because a shorter loan has less interest left to remove. There is no threshold you have to clear for extra payments to count; any amount shortens the tail.
On the same $25,000 loan, the first payment of $489.15 is $135.42 interest and $353.73 principal. The final scheduled payment is only $2.64 interest and $486.51 principal. The payment never changes, but its makeup does, because the balance it is charged against keeps shrinking.
This is why an extra payment early in a loan buys more than the same payment late in it, and why refinancing into a fresh long term resets you to the interest-heavy end of the curve even when the rate improves. Open the amortization schedule under the calculator to watch the split shift row by row on your own loan.
Suppose you have $1,200 to put at the same $25,000 loan. Paying it all today clears the loan in 4 years 9 months with $3,900.76 of interest. Spreading the identical $1,200 over a year as $100 extra a month clears it in 4 years 9 months with $3,956.82 of interest. The lump sum wins by $56.06, because every dollar in it starts working a few months earlier.
The gap is small in absolute terms, which is the practical point: timing matters less than consistency. A monthly amount you can actually sustain beats a lump sum you keep postponing.
The biweekly trick is to pay half your monthly amount every two weeks. There are 26 two-week periods in a year, so you make the equivalent of 13 monthly payments instead of 12. On the $25,000 example, a biweekly schedule of $244.58 retires the loan in 119 payments, roughly 55 months, with $3,906.04 of interest instead of $4,349.22, a saving of about $443.18.
That figure assumes interest accrues each two-week period at 1/26 of the annual rate and that the lender credits each payment when it arrives. Lenders differ: some hold biweekly payments and apply them monthly, which removes most of the benefit, and some third-party services charge a setup or per-payment fee. Paying one extra scheduled payment a year yourself gets you close to the same result with no middleman.
When there is a single extra $100 and several balances, the arithmetic is not neutral about where it goes. Take two loans of $5,000, each with 36 months left, one at an illustrative 18% and one at 6.5%. Aiming the $100 at the 18% loan clears it 15 months early and saves $646.53. The same $100 aimed at the 6.5% loan clears it 15 months early and saves $214.37, roughly $432.16 less.
Both loans finish about the same number of months early, because the balances and the extra payment are identical. What differs is the interest that never gets charged, and that is set by the rate: the higher-rate loan was charging more for every dollar you removed.
Rate wins over balance size in pure interest terms, because the rate is what prices every dollar still owed. Some people clear the smallest balance first instead, to remove a payment from the monthly list and keep going. The math does not settle that preference; it only tells you what the difference costs, which you can measure for your own loans by running each one through the calculator with and without the extra payment.
This page is a calculator and an explanation of the arithmetic, not financial advice. Whether paying a loan down early is the right use of your money depends on your rate, your other debts, and your situation.
No. The scheduled payment stays the same; extra amounts shorten the tail of the loan. Your required payment only changes if the lender formally recasts or refinances the loan.
Dollar for dollar, sooner beats later, because principal removed early stops accruing interest for the longest time. A lump sum today saves more than the same total spread over the year, but regular extra payments are easier to sustain.
Yes, mostly because 26 half-payments a year equal 13 monthly payments rather than 12. The saving depends on your lender crediting each payment when it arrives; some hold biweekly payments and apply them monthly instead.
Closing an installment account can slightly change your credit mix and average account age, and scoring models weigh those differently. Carrying a balance purely to keep an account open is a separate question from what a loan costs you in interest.
Paying a loan early is a guaranteed return equal to the loan's interest rate. Whether investing beats that depends on rates, risk, and taxes; this calculator shows the guaranteed side of that comparison. It is not financial advice.