What this calculator does
This calculator estimates the highest home price you can support in San Francisco using the two debt-to-income limits lenders commonly use: housing costs as a share of gross income (front-end) and all debts as a share of gross income (back-end). Unlike a basic affordability tool, it includes San Francisco's property tax, home insurance and HOA or condo fees, which change the answer a lot from city to city.
San Francisco has some of the highest rents and home prices in the country, with a large share of housing in older buildings covered by the city's rent ordinance. Neighborhoods range from the Mission and SoMa to the Sunset, Richmond and Bernal Heights, and fog belt western neighborhoods often cost less than central ones.
How to use it
- Enter gross income for everyone on the loan and your monthly debt payments.
- Enter the cash you have for a down payment.
- Set the mortgage rate and term.
- Adjust the 28% / 36% limits if your lender uses different ratios (some programs allow up to 43% or more on the back end).
- Check the local property tax, insurance and HOA defaults and replace them with numbers from listings.
The formula
Maximum housing payment = the lower of (income ÷ 12 × front-end %) and (income ÷ 12 × back-end % − other debts). The price is solved so that principal and interest on (price − down payment), plus property tax and insurance as a percentage of price, plus HOA dues, equals that payment.
Worked example for San Francisco
Household income $200,000, $400 of other debts, default down payment and local costs:
| Item | Monthly |
|---|---|
| Gross monthly income | $16,667 |
| Existing debt payments | -$400 |
| Principal and interest | $3,165 |
| Property tax at 1.18% a year | $620 |
| Home insurance at 0.25% a year | $131 |
| HOA / condo fees | $750 |
| Total housing payment | $4,667 |
Estimated maximum home price: $630,742. Loan of $500,742 with $130,000 down; total housing payment $4,667 a month.
What limits buying power in San Francisco
Under Proposition 13, a San Francisco home is assessed at its purchase price and the assessed value can grow no more than 2% a year. The 2025-26 rate is 1.18268325%, combining the 1% base with voter-approved bonds. Owner-occupants can claim a $7,000 homeowners' exemption.
Insurance can also swing the payment; get a quote before you commit to a price range.
Common mistakes and tips
- Using take-home pay instead of gross income — lenders use gross.
- Leaving out HOA or condo fees, which count just like property tax.
- Emptying savings for the down payment — lenders and co-op boards often want reserves.
- Assuming the maximum is comfortable; a price below it leaves room for repairs and rate changes.
- Forgetting PMI when putting down less than 20% on a conventional loan.
Frequently asked questions
How much house can I afford in San Francisco?
With the default inputs on this page, the estimate is $630,742. Your result depends mostly on income, debts, down payment and the mortgage rate.
What is the 28/36 rule?
A common guideline: housing costs up to 28% of gross income and total debt payments up to 36%. Many loan programs allow higher ratios with strong credit or reserves.
Why does property tax matter so much in San Francisco?
Property tax is paid every month through escrow, so a higher rate leaves less room for the loan itself. San Francisco's effective rate is set in the defaults and explained in the property tax calculator.
Does this replace a lender pre-approval?
No. A lender reviews credit, income documents and the specific loan program. Use this estimate to plan before talking to lenders.
Sources
Disclaimer
This calculator provides estimates for educational purposes only and is not financial, tax, legal, real estate, or insurance advice. Consult a licensed professional before making decisions.