Mortgage lenders have a number for you, and it has nothing to do with your credit score.
It's your debt-to-income ratio, or DTI, and it quietly decides how much house you're allowed to buy, what interest rate you'll pay, and in a growing number of cases, whether you get a loan at all.
Add up every monthly debt payment — car loan, student loans, minimum credit card payments, personal loans, plus the new mortgage you're hoping to take on.
Divide that total by your gross monthly income before taxes.
A household earning $7,000 a month with $2,100 in total debt payments sits at 30%.
For years, many conventional lenders preferred to see that number at or below 36%.
During the pandemic-era housing boom, some buyers pushed past 43% and still got approved.
Fannie Mae and Freddie Mac generally cap most conventional loans around 45% to 50% DTI, and lenders often add stricter "overlays" on top of those limits.
Cross the line and you're not negotiating a rate — you're getting a denial letter.
The math gets brutal fast in today's market.
A $400,000 mortgage at 7% runs about $2,660 a month before taxes and insurance.
Add a $450 car payment and $200 in minimum credit card payments, and you need roughly $7,360 in gross monthly income just to hit a 45% DTI.
Many families that could comfortably afford a home five years ago can't qualify today — not because their income dropped, but because rates and everyday prices ate the difference.
Credit cards are the hidden saboteur here.
Minimum payments count against your DTI, and with average card APRs above 20%, balances have a way of creeping up.
Someone carrying $12,000 across three cards might owe $350 a month in minimums — real money that shrinks their mortgage ceiling by tens of thousands of dollars.
Paying those balances down before applying can do more for your approval odds than shopping around for a better rate.
If you're hoping to buy in the next year, run your own numbers now.
Pull your three credit reports, total your minimum payments, and calculate your DTI honestly.
Lenders typically want to see it under 43% for the best shot at approval, and some loan programs allow higher limits with compensating factors like large cash reserves.
Pay down revolving balances rather than just paying on time — the ratio reacts to what you owe, not your payment history.
Avoid financing a car within six months of a mortgage application, since that payment lands directly in the calculation.
And if your DTI is borderline, consider a smaller loan amount or an FHA loan, which can sometimes allow ratios up to 50% with strong credit and reserves.
None of this is glamorous, but it's the difference between a pre-approval and a rejection.
The takeaway is simple: in a high-rate market, your DTI is a budget with teeth.
Final Thoughts
Treat it like a monthly bill you're trying to shrink, and the mortgage math starts working in your favor again.