Debt-to-Income (DTI) Calculator
Before a bank approves your mortgage, it runs one quiet calculation on your finances. Total monthly debt payments, divided by gross monthly income. That percentage decides whether you're an easy yes, a maybe, or a hard no. This calculator shows you exactly what the lender sees, which risk band you land in, and what to fix before you apply. It takes ten seconds, costs nothing, and tells you whether your debts look healthy or dangerously stretched from the outside. If the answer surprises you, the presets below show how ordinary households land in very different bands.
How the debt-to-income calculator works
DTI is brutally simple. Add up every monthly debt payment you owe, divide by your gross monthly income, multiply by 100. The calculator does that, then drops your number into a risk band lenders actually use. With the default numbers ($2,700 in monthly debts on $6,000 of income), you land at 45.0%, which is High risk. That's the whole point of this tool: seeing your finances through a lender's eyes before they do.
Notice what counts as income: gross, not take-home. Taxes get ignored because the lender's formula ignores them. And notice what counts as debt: minimum monthly obligations, not total balances. A $10,000 card balance matters less to this formula than the $150 minimum you're stuck paying on it. Weird, but that's how the industry does it.
Formula
The first number is the back-end DTI, the one most lenders care about most. The second is the front-end (or housing) ratio, which isolates what your roof costs you. Lenders often check both. You can be fine on one and flunk the other, which is why this calculator shows both.
Then comes the rating: under 20% is Excellent, 20–36% is Good, 36–43% is Caution, and above 43% is High risk. These bands mirror common underwriting practice. They aren't law. Individual lenders and loan programs draw their own lines. But they tell you roughly where you stand.
Example
Walk through the defaults by hand. Monthly debts: $1,800 (housing) + $400 (car) + $250 (student loans) + $150 (card minimums) + $100 (other) = $2,700. Gross income: $6,000.
Back-end DTI = $2,700 ÷ $6,000 × 100 = 45.0%. Front-end ratio = $1,800 ÷ $6,000 × 100 = 30.0%. Rating: High risk.
Look at what that means in plain English: 45 cents of every pre-tax dollar is already spoken for before food, gas, or savings. A mortgage lender sees a borrower with almost no slack. One surprise (a car repair, a medical bill) and payments start competing with each other. That's exactly the picture the High risk label is describing.
How to read your results
Start with the rating. Excellent and Good mean debt is a manageable slice of your income. Lenders are comfortable, and you should be too. Caution (36–43%) means you're in the zone where lenders start asking questions. Above 43%, you're in High risk: most conventional mortgage lenders want the back-end ratio at or below roughly 43–45%, and many get uncomfortable well before that. Some loan programs are more flexible when other factors (credit score, cash reserves, stable job history) look strong, but the general direction is the same: lower is easier.
Then compare the front-end and back-end numbers. A 30% housing ratio with a 45% total DTI (like the default) tells a specific story: housing alone is borderline fine, but everything else stacked on top is what's sinking you. The fix isn't a cheaper apartment. It's the car, the cards, or the student loans. Flip the pattern (high housing ratio, low everything else) and the fix is the opposite. The split tells you where to swing the axe.
If you're house hunting soon, this ratio is one of the levers you can actually move before applying. Our DTI and mortgage guide walks through which debts to attack first for the fastest ratio drop. Paying off a $400 car loan moves DTI six times more than shaving $400 off a card balance, because this formula only sees monthly payments. Work the formula, not your feelings.
Scenario comparison
Three households, three different DTI stories. Same calculator, wildly different mortgage conversations.
| Scenario | Monthly debt | DTI | Rating |
|---|---|---|---|
| Healthy ($8k income, $1.2k housing) | $1,600 | 20.0% | Good |
| Borderline ($5k income, $1.4k housing) | $2,000 | 40.0% | Caution |
| Renter ($4.5k income, $900 rent) | $1,600 | 35.6% | Good |
The Healthy household could borrow more house tomorrow. The Borderline one should pay down debts before talking to a lender. And the Renter, with the lowest income of the three, still lands in Good, because the ratio is about proportion, not salary. That's the encouraging part: DTI is fixable without a raise.
Frequently asked questions
What's the difference between front-end and back-end DTI?
What DTI do mortgage lenders actually want?
Does my DTI affect my credit score?
Should I use gross income or take-home pay?
Do utilities, insurance, and groceries count as debt?
What's the fastest way to lower my DTI?
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Sources & methodology
Every number on this page is computed in your browser with plain JavaScript. Nothing you type is sent anywhere. The back-end DTI is total monthly debt payments divided by gross monthly income, times 100; the front-end ratio is the housing payment alone over the same income. The rating bands (under 20% Excellent, 20–36% Good, 36–43% Caution, above 43% High risk) reflect common underwriting practice, not a single lender's policy. Read our full methodology for details.