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Loan Planning
Loan Payment Calculator: Monthly Payment and Total Interest
Calculate monthly loan payments, total interest, payoff date, extra payment savings, and a yearly amortization schedule for personal loans, auto loans, and fixed-rate debt.
Loan details
Optional principal prepayment.
Required monthly payment
$0
Payoff time with extra
0 months
Total interest
$0
Interest saved
$0
Adjust loan terms to compare monthly payment and total interest.
| Year | Payments | Principal | Interest | Ending balance |
|---|
Payment formula
Payment = P x r / (1 – (1 + r)^-n), where P is principal, r is monthly rate, and n is number of payments.
Added checks
This version handles 0% APR, blocks payments that cannot amortize the loan, and shows how extra monthly payments may reduce interest.
Monthly loan payment formula
The calculator uses the standard fixed-rate amortization formula and also supports 0% APR loans.
- Payment = P x r / (1 – (1 + r)^-n).
- P is principal, r is monthly APR, and n is number of payments.
- At 0% APR, payment = principal / number of months.
Extra payment comparison
Extra monthly payments are applied to principal in the payoff schedule.
- Extra principal can reduce total interest.
- A higher payment may shorten the payoff timeline.
- The yearly table shows balance, interest, and principal progress.
When to use it
This page is useful before accepting a loan offer or comparing financing choices.
- Compare APR, term length, and fees.
- Estimate auto loans, personal loans, and other installment debt.
- Check whether a payment fits your monthly budget.
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Use these calculators to connect loans with income, mortgage, and payoff planning.
Loan Payment Calculator FAQ
How do I calculate monthly loan payment?
Use the fixed-rate formula Payment = P x r / (1 – (1 + r)^-n), where P is principal, r is monthly interest rate, and n is total payments.
Does APR affect the monthly payment?
Yes. A higher APR increases interest cost and usually increases the required monthly payment for the same principal and term.
How do extra payments affect a loan?
Extra payments reduce principal faster, which can shorten payoff time and reduce total interest.
Can I use this for an auto loan?
Yes. It works for fixed-rate auto loans, personal loans, and similar installment loans.
Why does the calculator show an invalid payment warning?
If the payment does not cover monthly interest, the loan balance cannot amortize. Increase the payment or change the rate or term.
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