Loan / Mortgage Calculator
Calculate a loan or mortgage's monthly payment, total amount paid, and total interest.
How to use the Loan Calculator
- Enter the loan amount you plan to borrow.
- Enter the annual interest rate from your loan offer.
- Set the loan term, in years or months.
- Compare the monthly payment with the total interest — try a shorter term to see how much interest it saves.
About the Loan Calculator
A loan calculator estimates the fixed monthly payment for an amortizing loan — a mortgage, auto loan, or personal loan where equal payments are made every month until the balance is paid off. It uses the standard amortization formula M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1), where P is the loan amount (principal), r is the monthly interest rate (the annual rate divided by 12), and n is the total number of monthly payments (the term in years multiplied by 12).
Enter the loan amount, annual interest rate, and term, and it instantly returns the monthly payment along with two numbers that are easy to overlook when shopping for a loan: the total amount you'll pay back over the full term, and the total interest — the actual cost of borrowing on top of the principal. A 0% interest rate is handled as a special case (payment = principal ÷ number of payments), since the standard formula would otherwise divide by zero.
Worked example
Example: a $200,000 loan at a 6% annual interest rate over a 30-year term (360 monthly payments) comes to a monthly payment of $1,199.10, a total amount paid of $431,676.38, and total interest of $231,676.38 — more than the original loan amount, which is typical for a 30-year mortgage.
Where your payments go
With a fixed-rate amortizing loan, the payment stays the same but its makeup changes every month. Interest is charged on the balance still owed, so early payments are mostly interest. On a $200,000 loan at 6% over 30 years, the first month's interest is $200,000 × 0.5% = $1,000, which means only $199.10 of the $1,199.10 payment reduces the balance. As the balance falls, the interest share shrinks and the principal share grows; in the last years almost the whole payment goes to principal.
Comparing loan terms
Shorter terms raise the payment but cut the total cost dramatically. The same $200,000 at 6% over 15 years costs $1,687.71 a month — about $489 more — but total interest drops from $231,676.38 to $103,788.46. Paying extra is another lever: adding $100 a month to the 30-year payment clears the loan in about 24 years and 7 months and saves around $49,000 in interest. Check whether your lender charges prepayment penalties before planning extra payments.
Interest rate vs APR
The interest rate is what's used to calculate your payment, and it's what this calculator expects. The APR (annual percentage rate) adds lender fees and certain other costs, spread over the term, so it's usually a bit higher. Use APR to compare offers from different lenders and the interest rate to estimate the payment. Also confirm whether a rate is fixed or variable: a variable rate can change, and with it the payment.
Frequently asked questions
- What's the difference between the interest rate and the total cost of the loan?
- The interest rate is an annual percentage applied to the outstanding balance. The total interest is the actual dollar amount that accumulates over the entire term as a result of that rate — for long terms like a 30-year mortgage, total interest can exceed the original loan amount, which the interest rate alone doesn't make obvious.
- Why does a longer loan term lower the monthly payment but raise total interest?
- Spreading the same principal over more monthly payments reduces each individual payment, but it also means interest keeps accruing on the outstanding balance for longer, so the total interest paid over the life of the loan increases — even though each payment feels more affordable.
- Does this calculator include taxes, insurance, or fees?
- No. This calculates the principal-and-interest payment only, based on the standard amortization formula. Mortgages in particular often include additional monthly costs like property taxes, homeowners insurance, or PMI, which aren't part of this calculation and would need to be added separately.
- How does the payment change if I enter the term in months instead of years?
- The math is identical either way — years are simply converted to months (years × 12) internally. Switching the term unit to months lets you enter a loan with an unusual term, like an 18-month personal loan, without doing that conversion yourself.