The short answer: how much house can you afford depends on your income, existing debts, down payment, and current mortgage rates — not on the number a lender approves you for. Lenders calculate a maximum; you should calculate a comfortable one, and the two are often different numbers.
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Start with your debt-to-income ratio
Most lenders cap your total monthly debt (mortgage, car payments, student loans, credit cards) at around 43-50% of your gross monthly income, though the exact ceiling varies by loan program and lender. That’s the lender’s limit, not necessarily yours — plenty of buyers qualify for a payment that would feel uncomfortable month to month.
How much house can you actually afford, comfortably?
A common rule of thumb is keeping your total housing payment (principal, interest, property tax, insurance, and any HOA dues) under 30-35% of gross monthly income, though many Bay Area buyers stretch beyond that given local price levels. The real test isn’t a percentage — it’s whether you can still save, cover emergencies, and live the life you want after the mortgage payment clears your account each month.
A simple way to sanity-check your number
Take your gross monthly household income, multiply it by 0.32, and compare that to what a lender’s estimate shows for principal, interest, tax, and insurance on a home at your target price. If the lender’s estimate is meaningfully higher than your own comfortable number, that gap is worth sitting with before you write an offer — it’s much easier to adjust your search now than to feel stretched thin after closing.
Don’t forget the costs beyond the mortgage payment
Property taxes in California run roughly 1.1-1.3% of purchase price annually under Prop 13, plus any Mello-Roos or HOA dues specific to the community. Add homeowners insurance, and in some cases mortgage insurance if your down payment is under 20%. See Buyer Closing Costs in California for the one-time costs at closing, separate from these ongoing monthly ones.
Down payment size changes the math
A larger down payment lowers your monthly payment and can eliminate mortgage insurance, but tying up more cash also reduces your reserves for moving costs, repairs, and emergencies after you close. If a smaller down payment is the only way to buy now, see Down Payment Assistance Programs in California for programs worth checking your eligibility for.
Get pre-approved to see your real number
A budget you calculate yourself is a helpful starting point, but a lender’s mortgage pre-approval is what actually confirms how much house can you afford in the eyes of a seller. Run both numbers before you start touring homes seriously, and let the lower one guide your search.
A quick example
Say a household brings in $18,000 a month before taxes. A lender might approve a payment near $8,000 based on debt ratios alone, but a comfortable target closer to $5,500-$6,000 (30-35% of gross income) often leaves more room for savings, travel, and the unexpected. Running both numbers side by side, rather than anchoring only to the lender’s ceiling, is usually the difference between a purchase that feels exciting and one that feels tight every month.
Next step
Once you know your number, see Making a Competitive Offer in the Bay Area, or go back to the full Buyer’s Guide for every step in between.
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Laxmi Top Realtor · Intero Real Estate · DRE #02047105 · Serving Fremont, Milpitas, San Jose, Santa Clara, Union City & Newark. Equal Housing Opportunity. This guide is for general informational purposes and is not financial advice — consult a licensed lender for advice specific to your situation.