Scheduled payments only
First payment includes $156.25 interest and $344.70 principal.
- Monthly payment
- $500.95
- Total interest
- $5,056.92
- Total paid
- $30,056.92
- Estimated payoff
- Aug 2031
Loan Calculator
Estimate a fixed monthly principal-and-interest payment, then review total borrowing cost, month-by-month amortization, and how extra principal may change payoff timing.
Loan Calculator
Monthly payment
$500.95
Total Interest $5,056.92
Total Paid $30,056.92
Payoff Date Aug 2031
Educational estimate only. Assumes fixed rate, monthly payments, and extras applied to principal. Excludes lender fees, taxes, insurance, optional products, variable rates, late charges, and lender-specific payoff rules.
How it works
Formula and steps
The formula shows how the loan calculator turns your inputs into the result. Use it to check the calculation, then follow the example steps to see each part of the math.
Formula & steps
Fixed loan payment formula
Use this for fixed-rate loans with equal monthly payments.
M= Monthly paymentP= Loan principalr= Monthly interest rate as a decimaln= Total number of monthly payments- 1Convert the term to a number of monthly payments and divide the annual interest rate by 12 to get the monthly rate r.
- 2Use loan principal P, monthly rate r, and payment count n in the fixed-payment formula. At 0% interest, divide principal by payment count instead.
- 3For each month, calculate interest from the opening balance. The remainder of the scheduled payment reduces principal.
- 4Apply the entered extra payment to principal after scheduled principal, without allowing payment to exceed the remaining balance.
- 5Sum schedule interest and payments; compare the schedule without extras to calculate interest and time saved.
Worked examples
Example 1
$25,000 loan at 7.5% for 5 years
- 1
Convert annual rate and term
7.5% / 12 = 0.625% monthly 5 x 12 = 60 payments
- 2
Calculate fixed payment
M = 25000 x 0.00625(1.00625)^60 / ((1.00625)^60 - 1) M = $500.95 per month
- 3
Calculate lifetime cost from schedule
Total paid = $30,056.92 Total interest = $5,056.92
Example 2
Same loan with $100 extra principal each month
- 1
Keep scheduled payment and add extra principal
$500.95 + $100 = up to $600.95 per month
- 2
Recalculate balance month by month
49 payments instead of 60 11 monthly payments saved
- 3
Compare interest totals
$5,056.92 - $4,043.31 = $1,013.61 interest saved
Common uses
- Estimate a principal-and-interest payment before comparing loan offers
- Compare a shorter term's higher payment with its lower total interest
- Review total interest and total amount repaid
- Build a monthly amortization schedule
- Model recurring extra principal payments
Common mistakes
- Comparing only the monthly payment without checking total interest over the full loan term.
- Entering an APR that includes fees as though it were the note interest rate; they are related but not interchangeable.
- Assuming an extra payment is applied to principal automatically without checking lender instructions or prepayment terms.
- Treating the estimated payoff date as a lender payoff quote, which may include accrued interest, fees, or different rounding.
- Forgetting that taxes, insurance, fees, optional products, and variable-rate changes are excluded.
Loan guide
Payment, amortization, and payoff answer different questions
The monthly payment tells you the expected principal-and-interest obligation. Amortization shows how that payment changes the balance over time. Payoff analysis compares what happens when recurring extra principal is added.
Use this page when the loan amount, fixed rate, and term are known. For deeper schedule inspection, use the dedicated amortization calculator. A future payoff calculator will start from the current balance and known payment instead of original loan terms.
Fixed-rate loan example
These figures use the same calculation engine as the interactive calculator, with a $25,000 loan, 7.5% fixed annual interest rate, 5-year term, and first payment in September 2026. Values are rounded to cents for display.
Add $100 toward principal monthly
The scheduled payment stays $500.95; the calculator adds up to $100 in principal each month until the final payment.
- Payments
- 49
- Total interest
- $4,043.31
- Interest saved
- $1,013.61
- Estimated payoff
- Sep 2030 (11 months sooner)
What monthly payment includes
The result is scheduled principal and interest for a fully amortizing, fixed-rate loan. It excludes origination fees, taxes, insurance, optional products, and other charges unless they are already part of the entered principal. Compare total paid and total interest—not the monthly payment alone—when testing terms.
How amortization changes each month
Interest is calculated from the opening balance each month. The scheduled payment minus that interest reduces principal. Earlier payments generally contain more interest because the balance is larger; later payments contain more principal. The table keeps full calculation precision, while displayed amounts round to cents.
How extra payments affect payoff
The calculator applies the entered extra amount to principal every month after scheduled principal. A lower balance then produces less future interest. The final extra amount is capped so the payment never exceeds the modeled balance. Real lender handling may differ; verify principal-payment instructions and prepayment terms before sending extras.
Interest rate is not always APR
The calculator input is the fixed interest rate used for monthly interest. APR is a broader cost measure that can include the interest rate plus lender fees. Entering APR here treats it as the note rate; it does not reproduce a disclosure calculation or add fees. Compare lender offers using matching disclosed measures.
Model assumptions and limits
The model assumes one fixed annual rate, monthly interest, regular monthly payments, and no missed or late payments. It does not model daily simple interest, adjustable rates, balloon payments, interest-only periods, irregular lump sums, lender-specific rounding, or an exact payoff quote. The start month labels the schedule; an exact due day is not modeled.
Choose more specific loan tool
Use auto loan calculator when price, tax, down payment, trade-in, and fees determine financed amount. Use personal loan calculator for origination-fee and net-proceeds estimates, or student loan calculator for student-debt scenarios.
FAQ
It estimates the fixed monthly principal-and-interest payment, total interest, total paid, payoff month, and amortization schedule from the amount, rate, term, and optional extra monthly principal you enter.
Monthly interest is calculated from the balance before payment. The remaining scheduled payment reduces principal. As the balance falls, interest usually decreases and more of the fixed payment goes to principal.
A longer term often lowers the monthly payment but usually increases total interest when the amount and rate stay the same. Compare both the payment and lifetime cost.
An amortization schedule shows how each monthly payment is split between interest and principal, and how the remaining loan balance falls over time.
The calculator applies extras to principal after scheduled principal. This can reduce later interest and shorten payoff, but confirm how your lender applies extras and whether your contract has a prepayment penalty.
Enter the fixed note interest rate used to accrue loan interest. APR may include lender fees and can differ from the interest rate, so entering APR does not make this calculator include those fees.
No. It models principal and interest only. Add relevant costs separately and compare the calculator estimate with lender disclosures before making a borrowing decision.
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