Estimate monthly principal and interest, total interest, and scheduled repayment for a fixed-rate mortgage.
It keeps the property value, balance, cash amounts, rate convention, payment timing, and comparison horizon visible so the result can be checked against an actual quote, statement, budget, or contract.
Calculation structure
Follow the money through time
Payment = P·r/(1−(1+r)^−n), where r is the entered nominal annual rate divided by 12.
Visual explanation
See which inputs change the result
Opening balanceinterest+principalScheduled paymentBalance declines across the entered termPayment = P·r/(1−(1+r)^−n), where r is the entered nominal annual rate divided by 12.
Read the estimate correctly
Use the result with its assumptions
A 300,000 mortgage at 5% for 30 years has a principal-and-interest payment of about 1,610.46 per month.
Taxes, insurance, association charges, mortgage insurance, and fees are excluded.
Quick guide
How to use this calculator
Enter every amount in one consistent currency.
Enter the rate convention and whole-number period requested by each label.
Review the result together with the calculator-specific assumptions and exclusions.
Calculation method
Calculation method
Payment = P·r/(1−(1+r)^−n), where r is the entered nominal annual rate divided by 12.
The calculation retains full floating-point precision internally and rounds only for display. Amortization advances one payment period at a time so principal, interest, extra payments, and the final payment remain explicit.
Worked example
Practical example
A 300,000 mortgage at 5% for 30 years has a principal-and-interest payment of about 1,610.46 per month.
Payment = P·r/(1−(1+r)^−n), where r is the entered nominal annual rate divided by 12.
Supported inputs
Precision and limits
Visible input limits
Numeric tokens accept at most 60 characters. Amounts are capped at 1e12, annual rates at 1000%, and mortgage schedules at 100 years or 1,200 monthly payments.
Estimate, not an offer
Results model only the entered values. A lender may use different day counts, payment timing, fees, rounding, qualification rules, or contractual allocation.
International scope
No currency, country, tax system, insurance rule, mortgage program, or lender policy is assumed. Location-dependent amounts must be entered explicitly.
Calculator-specific assumptions
Taxes, insurance, association charges, mortgage insurance, and fees are excluded.
