# MortgageMath US

> Mortgage calculators, sourced numbers and step-by-step guides for buying, refinancing and borrowing against a home in all 50 states and DC.

URL: https://mortgage-math-us.com/

## Quick answers

### How much house can I afford?

Lenders compare your monthly debts with your gross income. Freddie Mac suggests keeping housing costs under 30% of gross pay and all debts under 45%; Fannie Mae’s automated underwriting accepts up to 50%. On a $75,000 salary with no other debts, the 30% guideline points to a home of about $242,000 with 10% down at today’s average rate — see [the full $75k breakdown](https://mortgage-math-us.com/blog/how-much-house-can-i-afford-on-75k/).

### What are mortgage rates right now?

Freddie Mac’s weekly survey put the average 30-year fixed rate at 7.24% and the 15-year at 6.6%. Your own rate depends on credit, down payment, loan type and points, so compare Loan Estimates from several lenders on the same day.

### How much is PMI?

Freddie Mac estimates private mortgage insurance at about $30 to $70 a month for every $100,000 borrowed. It applies to conventional loans with less than 20% down and ends automatically when your balance is scheduled to reach 78% of the home’s original value — see [our PMI guide](https://mortgage-math-us.com/buying/pmi/).

### What credit score do I need to buy a house?

FHA loans allow scores from 500 (with at least 10% down) and 580 or higher for the 3.5% minimum down payment. Fannie Mae requires 620 on manually underwritten fixed-rate loans; its automated system no longer sets a minimum score but still prices and approves loans on credit risk.

### How much are closing costs?

The CFPB says closing costs typically run 2% to 5% of the purchase price, on top of the down payment. On the US median home value of $360,600 that is roughly $7,200 to $18,000.

### When should I refinance?

Refinance when the monthly savings repay the closing costs well before you expect to move or refinance again. Divide total costs by the monthly saving to get your break-even month, and walk away if you won’t stay that long — our [buying hub](https://mortgage-math-us.com/buying/) explains the costs involved.


## Sources

- [US Census Bureau, American Community Survey 2024 1-year](https://data.census.gov/table/ACSDT1Y2024.B25077?g=010XX00US) (2024 ACS 1-year)
- [CFPB](https://www.consumerfinance.gov/owning-a-home/prepare/figure-out-how-much-you-want-to-spend/) (Oct 28, 2026)
- [Freddie Mac Primary Mortgage Market Survey](https://www.freddiemac.com/pmms) (Week of Oct 29, 2026)
- [Freddie Mac My Home](https://myhome.freddiemac.com/blog/homebuying/how-much-can-you-afford) (Jan 22, 2026)
- [US Census Bureau, American Community Survey 2024 1-year](https://data.census.gov/table/ACSDT1Y2024.B25103?g=010XX00US) (2024 ACS 1-year)
- [Freddie Mac Research](https://www.freddiemac.com/research/insight/homeowners-insurance-costs) (2023 data)
- [Freddie Mac My Home](https://myhome.freddiemac.com/buying/breaking-down-pmi) (Oct 28, 2026)
- [Fannie Mae Selling Guide B3-6-02](https://selling-guide.fanniemae.com/sel/b3-6-02/debt-income-ratios) (Apr 2, 2025)
- [CFPB](https://www.consumerfinance.gov/ask-cfpb/when-can-i-remove-private-mortgage-insurance-pmi-from-my-loan-en-202/) (Oct 28, 2026)
- [HUD Mortgagee Letter 2026-11](https://www.hud.gov/sites/default/files/hudclips/documents/2026-11hsgml.pdf) (Oct 8, 2026)
- [Fannie Mae Selling Guide B3-5.1-01](https://selling-guide.fanniemae.com/sel/b3-5.1-01/general-requirements-credit-scores) (Apr 22, 2026)