Mortgage rates get all the headlines, but there's a less glamorous number that can sink a home loan before rates even matter: your debt-to-income ratio, or DTI.
It's the share of your gross monthly income that goes toward debt payments, and lenders treat it like a report card.
Miss the cutoff, and you can be denied even with a solid credit score and a steady job.
Add up your monthly minimum payments: car loan, student loans, credit cards, personal loans, plus the estimated mortgage payment you're applying for.
Divide that by your gross monthly income before taxes.
If you earn $6,000 a month and your total debt payments hit $2,700, your DTI is 45%.
Many conventional loans allow a DTI up to 43% to 45%, and some programs stretch to 50% with compensating factors like big cash reserves.
FHA loans often go higher, sometimes to 50% or beyond.
But here's the catch: just because a lender allows 50% doesn't mean you should sign up for it.
At that level, one car repair or medical bill can wreck your budget.
The sneaky part is what counts against you.
Lenders usually use the minimum payment on credit cards, not your actual balance.
So a $4,000 card with a $95 minimum only adds $95 to your DTI, which sounds harmless.
But if you're carrying five cards, those minimums stack up fast.
Student loans can be trickier, since lenders may use 1% of the balance or your actual payment, depending on the loan type.
If your DTI is too high, you have two levers: cut debt or raise income.
Paying down a credit card balance lowers the minimum, which lowers your ratio.
Paying off a small car loan entirely can knock several points off overnight.
On the income side, a raise, a side gig, or adding a co-borrower with steady earnings can all help.
Some buyers also shop for a cheaper home, which shrinks the proposed mortgage payment and the ratio along with it.
One more thing worth knowing: don't open a new credit card or finance a car while you're house hunting.
A new minimum payment can push you over the threshold right before closing, and lenders typically recheck your finances before the final approval.
Even a "no interest for 12 months" furniture deal counts against you if it adds a monthly minimum.
A quick gut check before you apply: keep total housing costs under about 28% of gross income and total debt under 36% if you want breathing room.
Those old-school targets aren't required, but they leave space for real life.
You can estimate your own numbers in about five minutes with a calculator and your last two pay stubs.
Opinion: DTI is one of the few parts of the mortgage process you can actually control, and most buyers ignore it until they're already stressed.
Final Thoughts
Spend an afternoon trimming a payment or two before you apply, and you'll walk into pre-approval with far more leverage.