Free Mortgage Calculator

How This Calculator Works

This mortgage calculator has two modes. "How much can I afford?" takes your income, existing debts, and down payment to determine the maximum home price using the 28/36 DTI rule. "Calculate my payment" takes a specific home price and shows your exact monthly payment with a full amortization schedule.

Understanding DTI Ratios

Debt-to-income ratio is the primary metric lenders use to determine how much you can borrow. The front-end ratio (28% guideline) looks at housing costs only: principal, interest, taxes, insurance, and HOA. The back-end ratio (36% guideline) adds all other monthly debts like car payments, student loans, and credit card minimums.

Frequently Asked Questions

What is the debt-to-income (DTI) ratio?

DTI is the percentage of your gross monthly income that goes toward debt payments. Front-end DTI counts only housing costs (mortgage, taxes, insurance, HOA). Back-end DTI includes all debts (car loans, student loans, credit cards, etc.). Most lenders prefer front-end DTI under 28% and back-end DTI under 36%.

How much mortgage can I afford?

Use the "How much can I afford?" mode above. Enter your gross annual income, any existing monthly debt payments, your planned down payment, and current interest rates. The calculator applies the 28/36 rule to find your maximum home price and shows the limiting factor.

What is the 28/36 rule?

The 28/36 rule is a widely used lending guideline. Your total housing payment (mortgage P&I + property tax + insurance + HOA) should not exceed 28% of your gross monthly income, and your total debt payments (housing + all other debts) should not exceed 36%. The calculator shows both ratios color-coded: green (safe), amber (stretching), or red (over limit).

15-year vs 30-year mortgage

A 15-year mortgage typically has a lower interest rate and much less total interest paid, but the monthly payment is significantly higher. A 30-year mortgage offers lower monthly payments and more cash flow flexibility. Toggle between terms in the calculator to compare. For a $300K loan at 6.8%, the 30-year P&I is about $1,957/mo vs $2,654/mo for 15-year, but the 30-year pays ~$404K in total interest vs ~$178K.

How is the monthly payment calculated?

The principal and interest payment uses the standard amortization formula. Property taxes are estimated as a percentage of the home's value (default 1.1%, the US average). Homeowner's insurance and HOA are added as flat monthly costs. The amortization chart shows how principal and interest portions shift over the life of the loan.

Is my data saved?

Your inputs auto-save to your browser's local storage and persist between visits on the same device. No account is required. Track all your debts with the Loan Payoff Calculator.