Auto Loan Payoff Amount Calculator
Estimate the amount needed to close a daily simple-interest auto loan. The calculator adds per-diem interest through the expected posting date, unpaid interest, fees, and an optional comparison with a lender payoff quote.
Estimated payoff amount$20,041.10
- Interest per day
- $4.11
- New interest through posting
- $41.10
- Total interest-accrual days
- 10
- Payoff if payment posts one day late
- $20,045.21
Assumes daily simple interest on the current principal balance.
A lender quote of zero is treated as not provided.
How to use this calculator
- Enter the current principal balance from the account or payoff statement.
- Enter the contract interest rate and the lender day-count basis.
- Count the days from the interest paid-through date through the date the payoff should post.
- Add unpaid interest, fees, and the lender quote if you have one.
How the payoff estimate is calculated
An auto loan payoff is usually higher than the principal balance because interest keeps accruing until the lender receives and posts the final payment. This calculator treats the loan as daily simple interest, which is the common setup for auto loans where each day adds a per-diem charge to the unpaid principal.
The core formula is:
interest per day = P x r / Y
estimated payoff = P + (interest per day x N) + U + F
- P is the current principal balance.
- r is the contract annual interest rate as a decimal.
- Y is the selected 360- or 365-day basis.
- N is days since the interest paid-through date plus days until the payoff payment posts.
- U is unpaid interest already reported by the lender.
- F is payoff fees and other charges you enter.
The one-day-late result adds one more day of interest. That number is useful when mailing a cashier's check, waiting for a title department, or planning around weekends and holidays. If you enter a lender payoff quote, the difference row shows the lender quote minus this estimate. A positive difference means the quote is higher than the estimate; a negative difference means the quote is lower.
What moves the amount most
The principal balance and interest rate drive the daily charge. The posting delay matters because each extra calendar day usually adds another per-diem amount. The day-count basis also matters: a 360-day basis divides the annual interest over fewer days, so it produces a higher daily charge than a 365-day basis at the same balance and rate.
Previously accrued interest and payoff fees are added after the daily interest calculation. They can explain why a payoff statement is above the current balance even when very little time has passed since the last payment.
What this calculator leaves out
This estimate does not model precomputed-interest loans, Rule of 78 contracts, leases, prepayment penalties, payment reversals, rebates, refunds, or lender-specific rounding. It also cannot know the lender's exact paid-through date or posting date unless you enter those dates as day counts. An official payoff statement controls the amount needed to close the loan and release the lien.
Worked example
Suppose the principal balance is $20,000, the contract rate is 7.5%, the loan uses a 365-day basis, and the payoff should post 10 days after the interest paid-through date. The per-diem interest is $20,000 x 0.075 / 365, or about $4.11 per day.
Ten days of new interest is about $41.10, so with no separate unpaid interest or fees the estimated payoff is $20,041.10. If the payment posts one day late, the estimate rises to about $20,045.21.
Common questions
Why is my auto loan payoff higher than my principal balance?
The principal balance does not usually include interest that accrues after the last paid-through date. A payoff can also include unpaid interest, document fees, title fees, late charges, or other account adjustments. This calculator separates those pieces so you can see what is driving the difference.
How is per-diem interest calculated on a car loan?
Per-diem interest is the current principal multiplied by the annual interest rate as a decimal, then divided by the contract day-count basis. A 365-day basis uses 365 as the divisor, while a 360-day basis uses 360. Multiply that daily amount by the number of accrual days to estimate new interest through posting.
What does a 10-day payoff quote include?
A 10-day payoff quote generally starts with the payoff balance and adds enough daily interest to cover 10 calendar days. It may also include fees, unpaid charges, or lender-specific adjustments. If the payoff arrives after the quote period, another day or more of interest may be due.
Should I use 360 or 365 days?
Use the day-count rule in your loan contract or payoff statement. If the lender does not state one, ask before relying on the estimate. At the same balance and rate, the 360-day basis produces a slightly higher per-diem charge.
Why does the calculator differ from my lender payoff quote?
The lender may use a different paid-through date, posting date, day-count basis, rounding method, or payment-allocation rule. The quote may also include charges or adjustments you did not enter. Treat this estimate as a check on the quote, not a replacement for it.