Last reviewed September 2026
Sensible default. Modify inputs to match your situation.
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Loan calculator. Monthly payment, total interest, and payoff date for any fixed-rate installment loan, with an optional extra payment and the full amortization schedule.
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A general loan calculator covers the installment debt that doesn't fit a mortgage or a credit card: a personal loan, a debt-consolidation loan, a small business loan, a student loan refinance, or a loan from a family member with real terms attached. Enter the amount, term, and rate, and the calculator returns your required monthly payment, total interest over the life of the loan, an estimated payoff date, and the full year-by-year amortization schedule. Add an optional extra monthly payment to see exactly how much sooner the loan would be paid off and how much interest that extra money actually saves.
This calculator uses the standard fixed-rate amortization formula, the same one behind a mortgage or an auto loan payment: M = P[r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate (APR divided by 12), and n is the number of monthly payments. Each payment covers that month's interest first, with the rest going to principal, so the interest portion shrinks and the principal portion grows every month even though the total payment stays flat. On this calculator's $20,000, 48-month, 9.5% APR default, the required payment is $502.46/mo, with $4,118.21 in total interest over the four years, for a total of $24,118.21 paid. If the loan in question is specifically a mortgage, the Mortgage Payment Calculator runs the same core formula plus property tax, insurance, and PMI.
Enter 0 for the interest rate and the calculator switches to a straight division, loan amount divided by the number of months, with no interest charged at all, the math behind a promotional 0% financing offer or an interest-free loan from a relative. In that case an extra payment still shortens the term, it just doesn't save any interest since there wasn't any to begin with. If the loan is carrying real interest and there's a credit card balance in the mix too, run the numbers through the Credit Card Payoff Calculator first, since card APRs are usually far higher and typically deserve the spare dollar before this loan does.
It models a single fixed rate for the full term, not a variable or introductory rate that changes later, and it does not model origination fees, prepayment penalties, or a loan with irregular (non-monthly) payments. It is general-purpose: for a mortgage specifically, use the Mortgage Payment Calculator, which adds property tax, insurance, and PMI; for a vehicle purchase, use the Auto Loan Calculator, which adds trade-in value and sales tax; and for a credit card's revolving minimum-payment math, use the Credit Card Payoff Calculator instead, since a card doesn't amortize on a fixed schedule the way an installment loan does.
Monthly payment uses the standard fixed-rate amortization formula: M = P[r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate (APR ÷ 12), and n is the term in months; when the rate is 0, the payment is simply the loan amount divided by the term. Total interest with no extra payment is the sum of all scheduled payments minus the loan amount. With an extra payment, the schedule is simulated month by month: each month's interest is charged on the remaining balance, then the required payment plus the extra amount is applied, with the extra going straight to principal, until the balance reaches zero; total interest is the sum of interest charged across that simulation, and the payoff date adds the resulting number of months to today's date. Dollar figures round to the nearest whole dollar for display; the full-precision value is carried through every step before that final rounding. This is the same formula used by the Mortgage Payment Calculator and the Auto Loan Calculator.
Any fixed-rate, fixed-term loan that pays down in equal monthly installments: a personal loan, a student loan refinance, a small business loan, or any other installment debt. It is not built for a mortgage (use the Mortgage Payment Calculator for taxes, insurance, and PMI) or a credit card's revolving minimum-payment math (use the Credit Card Payoff Calculator for that).
On this calculator's $20,000, 48-month, 9.5% APR default, the required payment is $502.46/mo with $4,118.21 in total interest. Adding just $50/mo in extra principal, paid every month on a $10,000, 36-month, 12% APR loan, cuts the payoff from 36 months to 31 months and drops total interest from $1,957.15 to roughly $1,651.83, a savings of about $305 for finishing 5 months early, because every extra dollar comes straight off the balance interest is charged on.
Straight to principal, on top of the interest and principal already covered by your regular required payment, the same way most lenders apply an additional payment by default. Confirm with your own lender that extra payments are applied to principal immediately and not held or applied to a future due date, since a few loan servicers do the latter, which erases most of the benefit.
The calculator switches to a simple division: your loan amount divided evenly by the number of months, with $0 in interest. This is common for a promotional 0% financing offer or a no-interest loan from family.
Yes, the underlying amortization formula is identical. A mortgage adds property tax, homeowners insurance, and PMI on top of that same principal-and-interest calculation, which is why FigureNerd has a separate Mortgage Payment Calculator for home loans specifically.
Disclaimer. This calculator is designed to estimate a fixed-rate loan's monthly payment based on the inputs you provide. It is not financial advice or a loan approval, and actual loan terms are not guaranteed. Actual payment amounts may vary based on lender policies, your credit profile, and how a given servicer applies extra payments. Consult your lender before making any borrowing decision.