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Early loan payoff
How many months and how much interest an extra monthly payment saves on any fixed-rate loan.
CALCULATOR · MONEY · DEBT
Early Loan Payoff: Months & Interest Saved
An extra $100 a month on a $25,000 loan at 7.5% APR cuts 14 months off the term and saves $1,140.00 in interest — new payoff March 2031. Extra payments attack the term, not the monthly bill. See exactly what yours save below.
The 60-second rule
Extra payments shorten the term; the monthly bill stays the same. Baseline: 67 payments of $460 = $30,820.00 total, $5,820.00 of interest. With $100/month extra: 53 payments of $560 = $29,680.00 total, $4,680.00 of interest. Saved: 14 months + $1,140.00 interest — new payoff March 2031. Every extra dollar skips future interest at 7.5%.
The worked example, line by line
Defaults: $25,000 balance, 7.5% APR, $460/month, $100 extra. Monthly rate: 0.075 ÷ 12 = 0.00625. Baseline term: ceil(−ln(1 − 0.00625 × 25,000 ÷ 460) ÷ ln(1.00625)) = 67 payments; total $30,820.00, interest $5,820.00. With extra: payment becomes $560; ceil(−ln(1 − 0.00625 × 25,000 ÷ 560) ÷ ln(1.00625)) = 53 payments; total $29,680.00, interest $4,680.00. Months saved: 67 − 53 = 14; interest saved: $5,820.00 − $4,680.00 = $1,140.00.
Branch — $0 extra (baseline): 67 payments, $5,820.00 of total interest, payoff 67 months out. This is the price of minimum payments: nothing saved, nothing accelerated.
Branch — $300 extra: payment becomes $760; term falls to 37 payments; total $28,120.00, interest $3,120.00. Saved: 30 months + $2,700.00 interest — triple the extra payment more than doubles the savings because later payments are almost all interest you now skip.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Baseline term | ceil(−ln(1 − r·balance/payment) ÷ ln(1 + r)) | 67 payments at the defaults — the standard amortization term. |
| Baseline total interest | term × payment − balance | $5,820.00 — what the loan costs you if you never pay extra. |
| Months saved | baseline term − accelerated term | 14 months at $100 extra. |
| Interest saved | baseline interest − accelerated interest | $1,140.00 at $100 extra — the return on the extra payments. |
| New payoff date | today + accelerated term months | March 2031 — when the final accelerated payment lands. |
Who uses this
- The auto-loan borrower: $25,000 at 7.5% is the median 2026 car loan shape — $100/month extra saves $1,140.00 and the car is yours 14 months sooner.
- The personal-loan payer: higher APRs make extra payments even more valuable — run your rate and watch the interest-saved tile.
- The bonus allocator: deciding whether a $2,000 bonus should go to the loan or the emergency fund — price the loan payoff in months and dollars first.
- The debt-avalanche planner: stack this against your highest-APR balance — the highest rate gives the biggest per-dollar savings.
Accuracy & limitations
Math uses standard amortization with monthly compounding: term = ceil(−ln(1 − r·B/P) ÷ ln(1+r)), rounded up to whole payments. Honest limits: it assumes extra payments are applied to principal (most lenders do; some hold them as "paid ahead" — confirm), a fixed rate and fixed payment (variable-rate and income-driven plans behave differently), and no prepayment penalties (rare on consumer loans, common enough on some mortgages to check). The payoff date counts from today; the final payment is usually smaller than a full payment, which this rounds up conservatively.
Cite this calculatorBright Side Kit. “Early Loan Payoff.” brightoolbox.com, 2026.
Bright Side Kit. "Early Loan Payoff." https://brightoolbox.com/early-loan-payoff/ Accessed October 23, 2026.Frequently asked questions
How is the extra payment applied?
To principal — that is what this calculator assumes, and it is what most lenders do when you mark a payment "principal only." Some lenders instead hold it as "paid ahead," which shortens nothing; check your loan terms, because the $1,140.00 savings only exist when the extra attacks principal.
Does an extra payment shorten the term or lower the monthly bill?
It shortens the term. Your required payment stays $460; you just stop paying 14 months sooner. Lenders do not lower your monthly bill for paying extra — the term collapses instead, which is why the $1,140.00 in interest disappears.
How is the new payoff date calculated?
Today plus the accelerated term: 53 months from now is March 2031. The final payment is usually smaller than a full $560 — this calculator rounds up conservatively, so the real last payment lands slightly cheaper.
Are there prepayment penalties to worry about?
On most auto and personal loans, no — penalties are rare. Some mortgages (especially certain adjustable and subprime products) do charge them. Check your promissory note for "prepayment" before accelerating; a penalty can erase the savings this page computes.
Why 67 payments and not "about 5.5 years"?
Because amortization rounds up to whole payments: the exact formula gives 66.08 months, and you cannot make 0.08 of a payment — so the loan needs a 67th payment. The $30,820.00 baseline total uses all 67 payments, which is the number your lender would show.
Should I pay extra monthly or switch to biweekly?
Both shorten the term, but differently: biweekly half-payments make 26 half-payments = 13 full payments a year — one stealth extra payment annually. An explicit $100/month extra ($1,200/year) beats the biweekly trick's one extra $460 payment for most loan sizes. Run both through this calculator and compare the months-saved tiles.