State Mortgage Calculators

How the calculators work

The payment formula

Principal and interest use the standard fixed-rate formula: M = L × r(1+r)n / ((1+r)n − 1), where L is the loan amount, r is the monthly interest rate and n is the number of monthly payments. Property tax and insurance are added as one twelfth of the yearly amount.

Where the figures come from

  • Mortgage rate: the weekly 30-year fixed average from the Freddie Mac Primary Mortgage Market Survey, published through FRED at the Federal Reserve Bank of St. Louis. The current value is 7.4% for the week of October 8, 2026.
  • Home values: median value of owner-occupied homes, Census Bureau American Community Survey 2020–2024 5-year estimates (table B25077).
  • Property tax: median real estate taxes paid by homeowners, same survey (table B25103). The effective rate is the median tax divided by the median home value.
  • Income: median household income, same survey (table B19013).

Assumptions you can change

  • Home insurance starts at 0.4% of the home price a year. This is a general starting estimate and not a figure measured for each state, so replace it with a quote from an insurer.
  • Mortgage insurance (PMI) is estimated at 0.5% of the loan a year when the down payment is under 20%. Actual PMI depends on credit score and loan type.
  • The income guideline uses 28% of gross income for housing costs. Lenders set their own limits.

What the estimates leave out

  • Home values in the Census survey are what owners report, not current listing or sale prices.
  • Medians describe the middle of a state. Your county, city and school district can have very different tax rates.
  • Closing costs, points, special assessments, flood insurance and exemptions such as homestead credits are not included.
  • The Census Bureau limits the highest reported tax amount, which can understate tax in very high-tax areas.

Updates

The mortgage rate is refreshed weekly after Freddie Mac publishes it. Census figures are updated each year when a new 5-year release comes out. This site was last updated in October 2026.

Found a number that looks wrong? Write to contact@statemortgagecalc.com and include the page address.