Auto Loan Fixed Rate Calculator
This fixed-rate auto loan calculator estimates the monthly payment, total amount paid, and total interest for a straightforward fixed-rate installment loan. It includes sales tax and one-time fees in the financed amount when calculating payments.
Use the fields to enter the vehicle price, down payment and trade-in, any fees, the annual interest rate (APR), and the loan term in months. Results are numerical estimates intended for planning and comparison, not a guarantee of loan terms.
Inputs
Results
Amount to Finance
$30,050.00
Estimated Monthly Payment
$580.95
Total Paid (Principal + Interest)
$34,857.04
Total Interest Paid
$4,807.04
| Output | Value | Unit |
|---|---|---|
| Amount to Finance | $30,050.00 | USD |
| Estimated Monthly Payment | $580.95 | USD |
| Total Paid (Principal + Interest) | $34,857.04 | USD |
| Total Interest Paid | $4,807.04 | USD |
Visualization
Methodology
The calculator applies standard amortizing-loan mathematics: a fixed monthly rate derived from the annual rate (APR/12) and the annuity payment formula for level payments. Sales tax and one-time fees are added to the financed amount unless paid separately.
We follow numerical best practices by anchoring calculations to IEEE floating-point principles for arithmetic stability and recommending verification against lender disclosures. Outputs are rounded for presentation but underlying math uses full-precision arithmetic where supported.
Key takeaways
This calculator provides clear estimates for fixed-rate auto loans using standard amortization formulas and includes sales tax and fees in the financed amount by default.
Always compare calculator results to official lender disclosures and consider consulting a loan officer for binding offers. Results are approximate and intended for budgeting and comparison only.
Further resources
Expert Q&A
Does this calculator use APR or nominal interest rate?
Enter the annual percentage rate (APR) as provided by the lender. APR reflects the nominal rate; this calculator uses the APR to compute periodic interest compounded monthly. It does not add other annualized fees into APR unless you include them in 'fees'.
Will rounding affect the result?
Displayed numbers are rounded for clarity. Under the hood calculations assume full floating-point precision; minor cent-level differences can occur when lenders apply per-payment rounding or different compounding/period conventions.
How do I model a 0% interest offer?
Set Annual interest rate (APR) to 0. The calculator will compute equal principal payments: financed principal divided by the number of months.
Does sales tax always get financed?
By default this tool adds sales tax on the vehicle price to the financed amount. If you plan to pay sales tax up front, set 'sales tax rate' to 0 or subtract the tax from financed amounts before using the tool.
Is this a loan approval or an offer?
No. This is an estimation tool only. Final loan terms, fees, and APR are determined by lenders and contractual disclosures.
Sources & citations
- IEEE 754 Floating-Point Standard (numerical stability reference) — https://standards.ieee.org/standard/754-2019.html
- NIST — Guidance on Software and Calculation Accuracy — https://www.nist.gov
- ISO 9001 — Quality management principles — https://www.iso.org/iso-9001-quality-management.html
- OSHA — General safety and operational standards (reference for rigorous process control) — https://www.osha.gov
- Federal consumer protection — Review lender disclosures before signing — https://www.consumerfinance.gov