Home Affordability Calculator

Find out how much house you can afford based on your income and down payment. Free affordability calculator.

A home affordability calculator estimates how much house you can realistically afford before you start shopping. Rather than guessing from a list price, it works backward from the numbers that actually constrain a mortgage: your income, your down payment savings, the current interest rate, and the loan term. The guiding rule most lenders use is that your total monthly housing payment (principal, interest, taxes, insurance, and PMI if applicable) should stay under about 28% of your gross monthly income, and total debt payments under 36%. This calculator applies that logic so you get a target price range instead of a wish.

Use it to set a realistic budget before talking to a lender, or to see how a bigger down payment, a longer term, or a lower rate raises the price you can handle. Try the same income at 15-year versus 30-year terms, or with 10% versus 20% down, to see which lever moves the affordable price the most. The numbers run locally in your browser.

principal

loan

Result

2,022.62

Breakdown

Loan Amount
320,000

About Home Affordability Calculator

What is home affordability calculator?

A home affordability calculator estimates how much house you can realistically afford before you start shopping. Rather than guessing from a list price, it works backward from the numbers that actually constrain a mortgage: your income, your down payment savings, the current interest rate, and the loan term. The guiding rule most lenders use is that your total monthly housing payment (principal, interest, taxes, insurance, and PMI if applicable) should stay under about 28% of your gross monthly income, and total debt payments under 36%. This calculator applies that logic so you get a target price range instead of a wish. Use it to set a realistic budget before talking to a lender, or to see how a bigger down payment, a longer term, or a lower rate raises the price you can handle. Try the same income at 15-year versus 30-year terms, or with 10% versus 20% down, to see which lever moves the affordable price the most. The numbers run locally in your browser.

How to use this calculator

  1. Enter your home price.
  2. Enter your down payment.
  3. Enter your loan term.
  4. Enter your interest rate.
  5. Click the "Calculate" button.
  6. View your result instantly — the main result is displayed prominently at the top with a detailed breakdown below it.

When to use this calculator

  • Setting a realistic home-buying budget before pre-approval
  • Seeing how a larger down payment raises the price you can afford
  • Comparing 15-year versus 30-year terms effect on affordable price
  • Estimating how a rate change shifts your maximum price range
  • Checking the 28%/36% debt-to-income rule against your actual income

How the calculation works

Affordability is set by the debt-to-income (DTI) rule. First find the maximum monthly housing payment: M_max = gross_monthly_income x 0.28 (the front-end ratio). Then invert the amortization formula to solve for the largest loan principal that payment supports: P = M_max x [(1+r)^n - 1] / [r(1+r)^n], where r is the monthly rate and n the number of payments. Add the down payment to get the affordable home price: Price = P + down_payment. For example, $8,000/month gross income caps housing at $2,240/month. At 6.5% over 30 years (r = 0.005417, n = 360), P = 2,240 x [(1.005417)^360 - 1] / [0.005417 x (1.005417)^360] ~= $354,300. With $80,000 down (20%), the affordable home price is about $434,000.

Frequently Asked Questions

How are monthly mortgage payments calculated?▼
Monthly mortgage payments use the amortization formula M = P[r(1+r)^n]/[(1+r)^n-1], where P is the loan amount, r is the monthly interest rate, and n is the number of payments.
What is PMI and when do I need it?▼
PMI (Private Mortgage Insurance) is typically required when your down payment is less than 20% of the home price. It protects the lender, not you.

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