Payment Calculator
Free payment calculator. Solve monthly payment from loan amount, rate, and term — or solve the payoff time from a fixed monthly payment. Full amortization schedule with rate sensitivity and Excel export.
Frequently asked questions
How is a monthly loan payment calculated?
The standard amortizing-loan formula is M = P·r·(1+r)ⁿ / ((1+r)ⁿ − 1), where P is loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. This calculator uses that formula in Fixed Term mode.
How do you calculate the payoff time for a fixed monthly payment?
Rearrange the same formula to solve for n: n = −ln(1 − r·P/M) / ln(1 + r). If the payment M is less than or equal to r·P (the interest-only floor), the loan never pays off — this calculator flags that condition instead of returning an invalid answer.
What is the interest-only payment floor?
It is the monthly interest charge on your current balance: r·P, where r is the monthly rate. A payment below the floor does not reduce principal, and the balance actually grows over time (negative amortization). Every valid loan payment must exceed this threshold.
Should I choose a shorter loan term or a longer one?
Shorter terms have higher monthly payments but dramatically lower total interest — a $200k loan at 6.5% costs about $155k in interest over 30 years versus $58k over 15 years. Longer terms buy monthly flexibility at the cost of lifetime interest. Use the Rate Sensitivity view to see the tradeoff at your rate.
What is the difference between the Payment Calculator and a Mortgage Calculator?
The Payment Calculator is a pure loan-payment engine — principal, rate, and term (or payment). A Mortgage Calculator adds property tax, homeowners insurance, PMI, and HOA to build a full monthly housing cost. Use this tool for auto loans, personal loans, student loans, or any generic amortizing debt.
Does the calculator account for extra payments?
This tool focuses on solving the payment or the payoff term for a standard amortization. For extra-payment modeling (monthly, yearly, or one-time), use the Personal Loan Calculator or Mortgage Calculator, which show interest and time saved from prepayments.