Car Loan Payoff Calculator
Find the remaining balance, the time left and how much extra payments would save.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
Estimate an extra-payment scenario using a fixed monthly rate (APR ÷ 12). The model assumes each scheduled and extra payment is applied in full after monthly interest, with no fees or prepayment penalty. Your lender’s contract and payment-allocation rules determine the actual payoff; ask how to direct extra funds to principal.
Worked example
calculated with the default values below
Current loan balance 18,000 USD · APR (annual rate) 6.5 % · Months remaining 42 months · Extra monthly payment 100 USD/month Months to pay off with extra 35.0 months · Months saved 7.0 months · Interest saved (modeled) 414 USD · Current monthly payment 480.32 USD/month · Interest remaining without extra 2,174 USD
Method and assumptions
Formula basis and scope
Fixed monthly payment = P × i / (1 - (1 + i)^(-n)); i is annual percent / 1200. At zero interest, payment = P / n. Extra payments reduce the simulated outstanding balance each month.
Fixed nominal rate and monthly payments; fees, insurance, taxes and lender-specific daily accrual are excluded. The simulation stops at a one-cent balance or 1200 payments; prepayment penalties are excluded.
Data sources
Disclaimer
These calculators give estimates for general information only. Real fuel consumption, performance and range vary with driving style, load, terrain, temperature and vehicle condition. Do not rely on these results for towing limits, payload or braking decisions — use the rating plate of your vehicle.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
M = B·r ÷ [1 − (1+r)^−n]; B_{i+1} = B_i(1+r) − min(M + E, B_i(1+r))
- M
- Current monthly payment
- E
- Extra monthly payment
- r
- Monthly rate = APR% ÷ 100 ÷ 12
- n
- Original remaining months
- B_i
- Balance after i months
- B
- Current loan balance
Uses APR ÷ 12 and fixed monthly amortization; assumes extra payments are applied after interest and excludes fees or penalties. Actual allocation follows the lender contract.
Frequently asked questions
How does the extra-payment estimate work?
The calculator uses APR ÷ 12 and a fixed monthly amortization schedule. It assumes each extra payment is applied after that month’s interest and excludes fees and prepayment penalties. Actual payment allocation and payoff amounts depend on your contract and lender; ask how to direct extra payments to principal.
Does every extra payment go straight to principal?
No. This model simplifies payment allocation. A lender may apply a payment to fees or accrued interest before principal, and contract terms can vary. Confirm with your servicer how additional funds are handled.