Debt-to-Income (DTI) Ratio Calculator
Your DTI is the percentage of your gross monthly income that goes to monthly debt payments. Mortgage lenders use it as the single biggest qualification check after your credit score — and they apply hard ceilings, not guidelines. Plug your numbers in above and see where you land against the Conventional, FHA, VA, and USDA thresholds. Switch to "Max mortgage at my income" mode to run the math backwards: given what you make and what you already owe, the calculator shows the largest mortgage each program will let you borrow.
Output is for general illustration only and is not financial, investment, tax, or legal advice. Actual loan eligibility depends on credit profile, reserves, employment history, and the specific lender's overlays. See our Terms.
How this calculator works
Two simple formulas:
Front-end DTI = housing payment ÷ gross monthly income × 100
Back-end DTI = (housing + all other debt) ÷ gross monthly income × 100
"All other debt" means everything that shows up on your credit report or that the lender can document: car loans, student loans (including income-driven repayment amounts), credit card minimum payments (not balances), personal loans, alimony, child support. Utilities, groceries, insurance premiums, and gym memberships don't count — DTI is measuring credit obligations, not total spending.
The four mortgage-program ceilings shown above are:
- Conventional (Fannie Mae / Freddie Mac) — back-end cap of 43% on automated underwriting; up to 45% with compensating factors.
- FHA — back-end cap of 43% standard, up to 50% with compensating factors. The most forgiving of the major programs.
- VA — no hard cap; uses a residual-income test instead, but most underwriters target 41% informally.
- USDA (rural) — back-end cap of 41%, no exceptions on automated underwriting. Tightest of the four.
For a full walk-through with worked examples, see How to Calculate Debt-to-Income Ratio (DTI).
Reverse mode turns the formula inside out. Given your income and existing non-housing debts, it computes the largest PITI you could carry at each program's DTI ceiling, then translates that into a loan amount at the rate and term you specify. The "overhead" field accounts for the fact that PITI includes property taxes, insurance, and PMI on top of principal-and-interest — typically 25-35% additional on a low-down-payment loan.
Frequently asked questions
What is debt-to-income ratio (DTI)?
The percentage of your gross monthly income that goes to monthly debt payments. Lenders use it to predict whether you can afford a new mortgage on top of your existing financial obligations. Front-end DTI counts only housing payments; back-end DTI counts every monthly debt. Back-end is the number lenders care about most.
What is a good DTI for a mortgage?
Below 36% back-end is the comfortable threshold most financial planners recommend — room for retirement contributions, savings, and surprise expenses without the mortgage becoming a stress point. Lenders will go higher: Conventional caps at 43%, FHA at 50%. Each step up the DTI scale costs slightly worse pricing and far less flexibility once you actually have the mortgage.
Does the calculator include taxes and insurance?
It expects you to enter PITI — principal, interest, taxes, insurance, PMI, and HOA — as one combined monthly housing number. If you only know your principal-and-interest figure, add roughly 25-35% on top to estimate PITI, or use our mortgage calculator to get an exact number to paste in here.
What's the difference between front-end and back-end DTI?
Front-end is just the housing payment divided by income (target: under 28% for the comfortable case). Back-end adds car loans, student loans, credit card minimums, and everything else that shows up on your credit report (target: under 36% for the comfortable case; 43% is the conventional ceiling). Lenders calculate both, but back-end is the one that decides approval.
How does the reverse mode estimate qualifying loan amount?
It runs the standard mortgage payment formula backwards. The maximum PITI at each program's DTI ceiling is computed from your income minus your non-housing debts. That PITI is then reduced by the overhead percentage (default 28%, covering taxes, insurance, and PMI) to get a maximum P&I. Finally, the PMT formula is inverted to find the largest loan principal whose P&I at the specified rate and term equals that ceiling. The result is the maximum loan amount each program will let you borrow, rounded to the nearest $1,000.
Why is my VA result different from the others?
The VA doesn't enforce a strict DTI cap — it uses a residual-income test that varies by family size and region. Most VA underwriters target 41% back-end as an informal sanity check, and that's the number this calculator uses. Your actual approval depends on family size, region, and the dollar amount you have left after debts each month (the VA residual-income threshold is roughly $1,000/month for a family of four in most areas).
How accurate is the "approximate loan amount" in reverse mode?
Within a few percent for most cases. The math is exact (the PMT formula is exact), but the overhead estimate is a default — your actual taxes, insurance, and PMI can vary by location and lender. For loans under $300,000 in low-tax states, 25% overhead may be closer; for loans over $500,000 in high-tax states with PMI, 35% may be more accurate. Adjust the overhead field to match your situation.