28/36 for housing debt

Keep housing costs under 28% of gross income, and all debt payments under 36%.

Why it works

The classic mortgage-qualification ratios lenders use. Above them, one bad month starts to cascade.

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

Open Mortgage Calculator →

More in Finance

• The Rule of 72Money doubles in about 72 ÷ (interest rate %) years.
• Double the tax, round upIn the US, doubling the sales tax on the receipt gives a quick tip estimate.
• 114 triples, 144 quadruplesDivide 114 by the rate for tripling time, 144 for quadrupling.
• Ten years earlier ≈ twice the potAt typical market returns, starting to invest 10 years earlier roughly doubles your final balanc…

Browse all 96 rules of thumb →