House Affordability Calculator

Buying a home is the single largest financial commitment most people will ever make, and the two questions that determine whether it turns out well are asked in the wrong order almost every time. "How much house do I want?" comes first; "How much house can I afford?" comes second — or worse, gets answered by a mortgage lender who's motivated to say yes to the biggest possible loan. A trustworthy house affordability calculator 2026 flips the order, giving you a hard ceiling before you fall in love with a property that will strain your budget for the next thirty years.

The 28/36 rule. The most respected affordability benchmark in personal finance is the 28/36 rule, endorsed by consumer protection agencies and traditional lenders for decades. Your total monthly housing cost — principal, interest, property tax, homeowners insurance, and HOA — should not exceed 28% of your gross monthly income. Your total monthly debt payments, including housing, car loans, student loans, credit card minimums, and child support, should not exceed 36%. Anything higher and you start living paycheck-to-paycheck; anything much lower and you have real breathing room.

How the calculator works. This house affordability calculator 2026 takes your annual income, existing monthly debts, planned down payment, and current 2026 mortgage rates, then works backward. It computes the maximum monthly housing payment allowed by the 28/36 rule, subtracts property taxes and estimated insurance, and solves the standard amortization formula for the loan amount you can support. Add your down payment and you have the maximum purchase price a responsible lender would approve — and, more importantly, that your budget will actually tolerate.

A worked example. Household income $90,000 ($7,500/month). Existing monthly debts of $500 (car and student loans). Down payment of $40,000. At a 6.75% rate with 1.1% property tax, the 28/36 rule caps housing at $2,100/month and total debt at $2,700/month. The binding constraint is total debt: $2,700 – $500 in existing debts = $2,200 available for housing. After subtracting taxes and insurance, roughly $1,850 is available for principal and interest. That supports a loan of about $285,000, which with a $40,000 down payment means a maximum home price near $325,000. Push above that and DTI creeps past 43% — the point where FHA lenders start declining and personal finances start straining.

The costs buyers routinely underestimate. Property tax is huge and varies wildly: 0.3% in Hawaii, 2%+ in New Jersey and Illinois. On a $400,000 home, that gap is $6,800/year. Homeowners insurance has jumped 40%+ in wildfire and hurricane states since 2022. HOAs of $300–800/month can single-handedly disqualify a condo. Private mortgage insurance (PMI) adds 0.3–1.5% of the loan annually if you put down less than 20%. Maintenance runs about 1% of home value per year — $4,000 on a $400,000 home before you replace a roof or HVAC.

Beyond DTI: the emergency-fund test. Any affordability calculator that ignores savings tells only half the story. Before closing, most financial planners want to see: (1) at least three months of total expenses (including the new mortgage) sitting in cash, (2) closing costs of 2–5% of the purchase price already saved, and (3) a moving-and-furnishing budget of $5,000–15,000. If buying the maximum home the calculator allows would drain your emergency fund to zero, buy less house.

Expert tips. Get pre-approved before shopping — pre-qualification is a guess, pre-approval is a real underwritten number. Shop three lenders on the same day; rate differences of 0.25% save $20,000+ over the loan. Never buy at the top of what you're pre-approved for; lenders qualify at a ceiling, you should live under it. Fix your credit score before applying — moving from 700 to 760 can cut your rate by 0.375%. Consider a 15-year mortgage if you can afford the higher payment; you'll pay less than half the interest of a 30-year loan.

Common mistakes. Buying based on take-home pay rather than what the lender uses (gross income); forgetting that a raise doesn't happen until it happens; ignoring HOA and special assessments in condo purchases; assuming rates will drop and refinancing will save you; and stretching to buy in a "hot" market without regard to whether you can weather two years of falling prices. This house affordability calculator 2026 keeps you honest — the number it produces is the number your future self will thank you for respecting.