A Auto Loan Calculator computes monthly repayments and total interest on a loan. It applies the standard formula to the values you enter and returns the result instantly, without sending any data to a server. Borrowers use it to compare offers and to plan repayments.
Monthly payment, total interest, and total cost.
Standard amortization: monthly rate r = annual / 12, payment = P x r / (1 - (1+r)^-n).
Standard amortization for cars, trucks, SUVs, motorcycles.
Auto loans use the same amortization math as a mortgage. The biggest differences are shorter terms (typically 36-72 months), higher rates, and that the loan is secured by a depreciating asset. Sales tax is usually rolled into the loan amount in most US states.
Enter the negotiated vehicle price, your down payment, and any trade-in. The calculator adds sales tax to the financed amount, then applies the loan amortization formula.
The Auto Loan Calculator is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
This calculator uses the following formula:
M = P × [c(1+c)^n] / [(1+c)^n - 1] - same amortization as mortgage
The reason this formula works is rooted in the underlying physics, finance, or biology of the problem. Behind every calculator is a published, peer-reviewed equation or a widely accepted convention. We do not invent formulas; we apply standard ones from textbooks, government tables, professional bodies, and academic literature.
If you are curious about the math, the simplest way to verify is to plug in two known numbers and compare against a known result. The calculator should match published examples to within rounding precision.
Long terms drop the monthly payment but pile up interest, and you may stay underwater (owing more than the car is worth) for 2-3 years.
Typical guidance is 10-20% on a new car, 10% on used. Less down means higher payments and possible negative equity.
Most states allow it. It saves cash up front but adds interest charges over the life of the loan.
Yes - many credit unions refinance with no fees, and even a 1.5 point rate drop on a 4-year remaining loan saves real money.
The Auto Loan Calculator applies the standard formula for auto loan. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum guidance.
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours and update calculators when rules or formulas change.
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.