Calculator inputs
Estimate total mortgage interest over the life of a loan.
Enter the amount in the currency you are using. Keep the same currency across money fields.
Enter the annual percentage rate, not a decimal. For example, enter 6.5 for 6.5%.
Enter the length of the period using the unit shown in the label.
Controls rounding in the displayed result only; it does not change the underlying calculation.
How this calculator works
This calculator uses the standard amortising loan payment formula and subtracts principal from total payments.
Use this result as a planning estimate. Real lending, payroll, tax, health or construction outcomes can vary based on official rules, local costs and personal circumstances.
Formula
Worked example
A loan with a $3,160 monthly payment over 360 months pays total interest equal to total paid minus original principal.
Frequently asked questions
Why use this calculator?
It gives a fast estimate and helps compare related scenarios before moving to more detailed planning.
Is the result exact?
No. Treat it as a practical estimate and verify important numbers with official sources or qualified professionals.