28/36 Rule Calculator - Mortgage Affordability

A 28/36 rule calculator explains mortgage affordability using front-end and back-end debt-to-income limits with a focused calculation instead of a vague rule of thumb. The inputs mirror the decisions people actually need to make, and the output separates the headline number from supporting figures so assumptions are easier to audit. For searchers comparing alternatives, the 28/36 Rule Calculator gives a repeatable way to check whether a plan is realistic before money, paperwork, or an application is committed. It calculates 28% of gross monthly income for housing costs and 36% of gross monthly income for total debts, subtracts existing debts from the back-end limit, uses the lower payment capacity, removes taxes, insurance, and HOA dues, then converts the remaining principal-and-interest capacity into loan principal. Use the 28/36 rule calculator for setting a home-shopping budget, preparing for preapproval, comparing lender quotes, and testing the effect of debt payoff or higher property taxes. The examples below use real numbers and the same calculation path as the form, which makes them useful benchmarks when checking a similar situation. Running conservative, expected, and optimistic scenarios is especially helpful because it shows which input creates the most risk or the most room for improvement. Read the supporting lines before focusing on the final number. A secondary output can reveal whether the result is being driven by income, rate, time, taxes, depreciation, contribution percentage, or an allowance limit. If the answer is close to a decision threshold, change one input at a time and keep a short note explaining why that assumption is reasonable. That habit makes the 28/36 rule calculator more useful for conversations with lenders, payroll teams, landlords, accountants, advisors, or household decision makers. Loan programs can allow higher ratios, and households may choose stricter limits. Down payment, mortgage insurance, closing costs, credit overlays, and reserve requirements are not included. The result should be treated as a planning estimate, not a guarantee or professional opinion. Keep the assumptions with any decision record, compare the output with contracts, policies, statements, or plan documents, and ask a qualified professional when the number will affect lending, insurance, payroll, tax, accounting, or legal decisions.