Interactive calculator
Home Affordability DTI Checker
Most DTI tools stop at lender-style ratios. This one adds the expenses people actually feel after closing: utilities, maintenance, normal living costs, and leftover monthly cash.
DTI + leftover cash stress test
Home affordability DTI checker with leftover cash and stress-rate test
Estimate whether the mortgage works after taxes, insurance, PMI, HOA, utilities, maintenance, debts, normal expenses, and a higher-rate stress test.
Last updated 2026-05-04. Educational planning only.
Quick answer: Check front-end DTI, back-end DTI, true-cost burden, leftover cash, and stress-rate affordability in one calculator.
What makes this calculator niche
Most DTI tools stop at lender-style ratios. This one adds the expenses people actually feel after closing: utilities, maintenance, normal living costs, and leftover monthly cash.
Formula used
True-cost burden = true housing cost + monthly debts + living expenses รท gross monthly income
Result summary
Enter a scenario above to generate a planning summary.
Worked example
A household earning $110,000 per year may appear eligible for a large mortgage under a lender-style debt-to-income calculation. But if the same household has car payments, student loans, childcare, utilities, maintenance reserve needs, and normal living expenses, the true room in the budget may be much lower. This calculator compares the lender-style ratios against leftover monthly cash.
The stress-rate input is especially important when rates move quickly. A buyer who is comfortable at one rate may become tight if the rate increases before lock, if PMI is higher than expected, or if taxes and insurance are estimated too low.
How to interpret the result
Front-end DTI is useful, but it is not enough. Back-end DTI captures more debt, but it still does not fully show groceries, utilities, repairs, savings, or emergency reserves. The true-cost burden and leftover-cash checks help reveal whether the mortgage is affordable in daily life, not only on a lender worksheet.
A safer scenario usually has manageable housing cost, manageable total debt, and meaningful leftover cash after ordinary expenses. If one metric looks good but another looks strained, treat the result as a caution flag and test a lower purchase price or larger cash reserve.
Important limitations
This calculator does not decide whether a lender will approve you. Lenders may use different income calculations, credit overlays, loan programs, reserves, and debt rules. The calculator is intentionally more conservative because its purpose is household comfort, not maximum approval.
FAQ
What is front-end DTI?
Front-end DTI compares core housing cost to gross monthly income.
What is back-end DTI?
Back-end DTI compares core housing cost plus other monthly debts to gross monthly income.
Why add leftover cash?
DTI can look acceptable while the household still has too little cash left for savings, repairs, and normal life after closing.
Deeper affordability planning notes
Debt-to-income ratios are useful because they provide a quick relationship between income, housing cost, and monthly debt. They are also incomplete. A household does not live on gross income. It lives on the cash left after taxes, insurance, payroll deductions, debt, utilities, food, transportation, childcare, healthcare, savings, and repairs. This is why the calculator includes both DTI and leftover cash.
A buyer can appear safe under one ratio and strained under another. Front-end DTI may look reasonable because the housing cost is not too high relative to gross income. Back-end DTI may become tight after other debts are included. The true-cost burden may become tighter when utilities and maintenance are added. Leftover cash may reveal whether the household can still save after closing.
The stress-rate input is important because a buyer may shop during a moving rate environment. If the budget only works at the current rate and fails at a modestly higher rate, the buyer may need a stronger cash reserve or a lower purchase price before locking.
How to use the result responsibly
Do not use this calculator to determine the maximum possible approval. Use it to identify a comfortable range. If the result is close to a risk threshold, test a lower purchase price, reduced debt, higher down payment, or larger income reserve. The safer scenario is the one that still works when one or two assumptions move against the buyer.