How to use this loan calculator
Use the APR from the lender's offer, not the "interest rate" if they differ. APR includes origination fees and gives you a truer comparison between lenders. Enter the term in months for auto and personal loans (36, 48, 60, 72) or switch to years for longer loans.
The result shows the fixed monthly payment, how many payments you'll make, and how much of the total is interest. The last line, interest as a percentage of the loan, is the quickest way to compare two offers with different terms.
Longer term, lower payment, higher cost
Stretching a $25,000 auto loan from 48 to 72 months at 7.5% drops the payment from about $604 to $432. It also raises total interest from roughly $4,000 to $6,100. Dealers often lead with the monthly payment because it makes the longer loan look cheaper. Compare total interest instead, and keep the term shorter than the time you plan to keep the car so you don't end up upside down.
Personal loan vs credit card
If you're consolidating card debt, run both scenarios here. A $10,000 personal loan at 12% over 36 months costs about $1,960 in interest. The same balance on a card at 24% paid at $332 a month (the same payment) takes 46 months and costs roughly $5,200. The fixed schedule is also a forcing function — the loan ends; the card doesn't.
Fixed monthly payment
M = P × r / (1 − (1 + r)⁻ⁿ)
- M = monthly payment
- P = amount borrowed
- r = APR ÷ 12
- n = number of months
Frequently asked questions
+What's the difference between interest rate and APR?
The interest rate is the cost of borrowing the principal. APR adds lender fees (origination, processing) and expresses the total as a yearly rate, so it's the better number for comparing loans.
+Can I pay a loan off early?
Usually yes. Most auto and personal loans have no prepayment penalty, but check the agreement. Some loans use precomputed interest (the Rule of 78), which reduces the benefit of early payoff.
+What credit score do I need for the best rate?
Lenders reserve their lowest rates for scores above roughly 760. Scores in the 700s still get competitive offers; below 660, rates rise sharply and it's worth shopping credit unions.
+Does the calculator include taxes and fees on a car purchase?
No — enter the total amount financed, which should already include sales tax, fees and any add-ons rolled into the loan, minus your down payment and trade-in.