Payment Calculator
Solve for any unknown in a loan: enter the loan amount and rate to find the monthly payment, enter your budget and rate to find the maximum loan you can afford, or enter the loan amount and payment to find the payoff timeline. Works for auto loans, personal loans, mortgages, and any fixed-rate amortized loan.
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How It Works
Enter the loan amount, annual interest rate, and term in months. The calculator applies the standard amortization formula to compute the fixed monthly payment that fully repays the loan over the specified term.
M = P x r(1+r)^n / [(1+r)^n - 1]$25,000 at 6.5% for 60 months = $489.15/moEnter the monthly payment you can afford, the interest rate, and the term. The calculator reverses the payment formula to determine the maximum principal you can borrow while staying within your budget.
P = M x [(1+r)^n - 1] / [r(1+r)^n]$500/mo at 6.5% for 60mo = max $25,556 loanEnter the loan amount, interest rate, and your intended monthly payment. The calculator determines how many months it will take to fully pay off the loan at that payment level.
n = -ln(1 - Pr/M) / ln(1+r)$25,000 at 6.5% paying $600/mo = 47 monthsMultiply the monthly payment by the number of payments, then subtract the original loan amount. The difference is pure interest — the cost you pay for borrowing the money.
Total Interest = (Monthly x Months) - Principal$489.15 x 60 - $25,000 = $4,349 total interestRun the same loan amount and term at different rates to see how much each percentage point costs. This helps evaluate whether paying points upfront for a lower rate is worthwhile.
Compare: same P and n, different r$25K 60mo: 5% = $471.78/mo vs 7% = $495.03/moShorter terms mean higher monthly payments but less total interest. Longer terms reduce the monthly burden but increase the total cost. Finding the right balance depends on your cash flow and financial goals.
Compare: same P and r, different n$25K at 6.5%: 48mo = $593/mo ($3,467 int) vs 72mo = $421/mo ($5,302 int)Quick Reference
Common examples — verify instantly above.
$10K, 5%, 36mo
Monthly payment
$299.71
$20K, 6%, 48mo
Monthly payment
$469.70
$25K, 6.5%, 60mo
Monthly payment
$489.15
$30K, 7%, 72mo
Monthly payment
$512.90
$500/mo budget
Max loan at 6%, 60mo
$25,863
$400/mo budget
Max loan at 7%, 48mo
$16,602
$25K at 6.5%
Paying $600/mo, payoff
47 months
$15K at 5%
Paying $400/mo, payoff
40 months
Tips & Shortcuts
Use Find Loan Amount mode before car shopping to set a realistic budget based on the monthly payment you can comfortably afford.
Compare the total interest across different term lengths — the monthly savings from a longer term often costs thousands more in total interest over the life of the loan.
When negotiating a loan, focus on the interest rate and total cost rather than the monthly payment. Dealers often extend the term to lower the payment while increasing your total cost.
Use Find Loan Term to see how making slightly higher payments dramatically shortens the payoff timeline and reduces total interest.
Run the calculator at multiple interest rates to see the value of improving your credit score before applying for a loan.
Remember that the calculated payment covers only principal and interest. Budget separately for insurance, taxes, and any escrow requirements.
Common Mistakes to Avoid
Choosing the longest term just to minimize the monthly payment
A 72-month auto loan at 7% on $25,000 costs $5,328 in interest versus $3,467 for a 48-month term. Always compare total cost alongside monthly payment.
Not accounting for fees and taxes in the loan amount
The loan amount should include all financed costs: purchase price plus sales tax, title fees, and registration. Excluding these gives an artificially low payment estimate.
Ignoring the minimum payment threshold for Find Term mode
Your payment must exceed the monthly interest charge or the loan never pays off. The calculator warns you if the payment is too low, but it is important to understand why.
Comparing loans with different terms on monthly payment alone
A $25,000 loan at 6% for 48 months ($587/mo) versus 72 months ($414/mo) looks like $173 savings. But the longer loan costs $1,823 more in total interest.
Assuming the calculated payment includes insurance and taxes
This calculator computes principal and interest only. Property tax, insurance, PMI, and other costs are separate and can add 30% to 50% to the actual monthly housing cost.
Not verifying the interest rate type matches the calculator
This calculator assumes a fixed rate. If your loan has a variable or adjustable rate, the actual payments will change over time and this calculator shows only the initial payment.
Frequently Asked Questions
The monthly payment uses the present value annuity formula: M = P × r(1+r)^n / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the number of months. This creates equal payments that fully pay off the loan by the end of the term.
Switch to Find Loan Amount mode. Enter your maximum comfortable monthly payment, the interest rate, and the loan term. The calculator works backward from the payment formula to determine the largest loan that fits within your budget.
On long-term loans, even 0.5% changes compound significantly over hundreds of payments. On a $300,000 30-year mortgage, a 0.5% rate increase adds about $90 per month — over $32,000 over the life of the loan.
If your payment does not cover the monthly interest charge, the loan balance grows instead of shrinking. This is called negative amortization. The calculator will warn you if your payment is too low to pay off the loan.
This calculator works for any standard fixed-rate amortized loan including auto loans, personal loans, student loans, and mortgages. It does not apply to interest-only loans, adjustable-rate loans, or credit card minimum payments.
You can reduce payments by making a larger down payment, choosing a longer loan term, or securing a lower interest rate. However, longer terms increase total interest paid, so consider the total cost alongside the monthly payment.
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