Extra payment loan payoff calculator
A fixed-rate auto or personal loan, walked forward month by month with an extra payment on top: recurring or a single lump sum. The saving is a real simulation, never a rate-times-extra shortcut, and the final month is trimmed to the exact balance instead of overpaying.
Worked example — Interest saved by $100 extra a month on a $28,000 auto loan: $870. $28,000 at 6.4% over 60 months, paid off 10 months sooner
Price your own extra payment
Enter the loan and pick how the extra arrives. Every month accrues interest on the balance first, then applies the scheduled payment plus whatever extra is due that month, capped at what is actually owed so the last payment never overshoots into a negative balance.
$28,000 auto loan, $100 extra a month: 6.4% APR over 60 months, $100 extra applied every month starting immediately.
Advanced 1
Both lines start at $28,000. The extra-payment line reaches zero at 4 yr 2 mo, 10 months before the scheduled payoff.
How much sooner does $100 extra a month pay off a loan?
On a $28,000 loan at 6.4% over 60 months, an extra $100 every month clears the balance 10 months sooner, in 4 years 2 months instead of 5 years, and saves $870 in interest that would otherwise have accrued on the balance those extra dollars remove early. The saving is not the extra amount times the interest rate: it comes from re-running the whole loan with the extra applied and comparing the two totals, because every dollar of extra principal stops earning interest for every month it would otherwise still have been owed.
Months and interest saved by extra payment amount
Held at the default $28,000 loan and 6.4% rate, computed from the same engine the calculator above runs. The saving does not scale in a straight line: doubling the extra payment more than doubles the interest saved, because a shorter loan also front-loads more of every later dollar's principal reduction.
| Extra a month | New payoff | Months saved | Total interest | Interest saved |
|---|---|---|---|---|
| $50 | 4 years 7 months | 5 | $4,313 | $479 |
| $100 | 4 years 2 months | 10 | $3,923 | $870 |
| $150 | 3 years 10 months | 14 | $3,598 | $1,194 |
| $200 | 3 years 6 months | 18 | $3,324 | $1,468 |
| $300 | 3 years 1 month | 23 | $2,888 | $1,905 |
Recurring extra payments vs one lump sum of the same total
The same $3,000 total, paid two ways on the $28,000 loan above. Spread evenly at $50.00 a month across all 60 months it saves $479. Delivered once at month 12 it saves $811. Timing decides the winner, not the total: the same $3,000 paid at month 60, the loan's last scheduled payment, saves only $0, because there is no interest left on the balance for a late lump sum to remove. A lump sum beats a recurring payment of the same total only when it arrives earlier than the recurring payments would have, on average.
Extra payments on a personal loan
Personal loans carry higher rates than auto loans, so the same habit buys back more interest per dollar. On a $14,000 personal loan at 11.9% over 48 months, paying $150 extra every month clears the balance 16 months early and saves $1,285, against the $870 the lower-rate auto loan preset above saves at a similar-sized extra payment. Same arithmetic, worse rate, bigger payoff for the same dollar of extra.
The next question after this one
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