Mortgage Interest Calculator
Calculate the total interest paid over the life of a mortgage loan based on loan amount, interest rate, and loan term.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Mortgage Interest Calculator
Follow these steps to calculate your total interest, monthly payment, and total payment for a fixed-rate mortgage.
- Enter Loan Amount ($): Input the total amount you plan to borrow (e.g., 300000 for $300,000). Use positive numbers only.
- Enter Annual Interest Rate (%): Type the yearly interest rate as a percentage (e.g., 4.5 for 4.5%). Do not include the percent sign.
- Enter Loan Term (years): Specify the loan duration in whole years (e.g., 30). Only positive integers are accepted.
- Click "Calculate": Press the button or hit Enter on your keyboard. If any input is invalid, a red error message will appear below the field.
- View Results: The calculator shows:
- Total Interest Paid – the total cost of borrowing.
- Monthly Payment – your fixed monthly amount.
- Total Payment – loan amount plus total interest.
Note: All values are in US dollars. The calculator uses the standard amortization formula: M = P × [r(1+r)^n] / [(1+r)^n - 1]. Results are rounded to two decimal places.
Previous Results
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Frequently Asked Questions
Mortgage interest is the cost of borrowing money from a lender to purchase a home, expressed as an annual percentage rate (APR).
Total interest is calculated by subtracting the original loan amount from the total of all monthly payments over the loan term. The monthly payment formula used is M = P [r(1+r)^n] / [(1+r)^n - 1].
Yes, this calculator works for any fixed-rate amortizing loan, such as auto loans or personal loans, as long as the interest rate is fixed.
