How Much House Can You Actually Afford? The 28% Rule, Tested

You get pre-approved, and the number is bigger than anything you'd ever comfortably borrow. A friend counters with the 28% rule. Both of them are answering a different question than the one you're actually asking. The lender is telling you the maximum a bank will tolerate. The rule is a rough guardrail. What you need is the number that works when your actual income, your actual bills, and an honest look at ownership costs are all in the same room — and that number is almost always lower than both.

What the 28% Rule Is Really For

The 28% rule says your housing costs should stay under 28% of gross income, and the related 36% figure caps total debt. Those numbers exist because they're the ceilings banks use when deciding whether to approve a loan — they measure risk to the lender, not comfort for you. The counter-intuitive part: the rule is a sanity check, not a target. If 28% of your gross income feels tight because you live in an expensive city or you're carrying other debt, you're allowed to aim lower. The rule was never a budgeting method; it's a filter to keep obviously bad loans from happening.

The Honest Way to Size a Loan

Start with net income, not gross. Run your pay through an income tax calculator so you're working with what actually lands in your account, then build the real monthly number: principal and interest, property tax, insurance, and a maintenance allowance. That's the PITI-plus number, and it's higher than the shiny "monthly payment" a calculator spits out before you add the rest. This is where a mortgage calculator earns its keep — not to tell you the payment, but to let you try different prices, rates, and down payments quickly and see which combination keeps your total under your real budget.

Then stress-test it. Ask what the payment looks like at a rate one or two points higher, and whether your budget survives a lean month or a job change. Ownership is a thirty-year commitment with yearly surprises, and the math should work for the worst realistic case, not just today's. One number worth seeing before you commit: the total interest over the life of the loan. A compound interest calculator shows you what that rate does across three decades, and for most people it's the moment the "affordable" monthly payment stops looking so cheap.

The Verdict Is Your Budget's, Not the Calculator's

The calculator gives you a number; your budget gives you the verdict. We walked through the basics in our guide for first-time home buyers, and the same principle holds one step deeper: pre-approval is the bank's ceiling, 28% is the industry's guardrail, and the number that actually works is the one that leaves you sleeping well every month. Aim for that one.