If you're house hunting this spring, the number that decides whether you get the keys probably isn't your credit score.
It's a plain arithmetic figure most buyers have never bothered to calculate: your debt-to-income ratio, or DTI.
Lenders use it to answer one question — after you pay everyone else, how much room is left for a mortgage?
Add up every monthly debt payment: car loans, student loans, minimum credit card payments, personal loans, plus the new house payment you're hoping to take on.
Divide that total by your gross monthly income before taxes.
That percentage is your DTI, and it's quietly steering the biggest purchase of your life.
Most conventional loans today will stretch to 43%, and some government-backed loans push past that with compensating factors like cash reserves or a long job history.
Cross the line and you're not rejected outright — you're offered less house.
A ratio that runs 5 points hot can shave tens of thousands off your maximum loan amount, which in a market where inventory is tight often means losing the bid.
Paying down a credit card balance helps twice: it lowers the balance and shrinks the minimum payment lenders count against you.
Paying off a small car loan entirely can wipe an entire line item off the calculation.
Even a modest raise helps, because the denominator grows while the debts stay flat.
A $200 monthly payment eliminated on a $70,000 income frees up roughly 3.4 percentage points of ratio — often the difference between a comfortable approval and a stretched one.
One trap catches people constantly: buying a car or financing furniture right before applying.
That new $450 payment doesn't just cost $450 — it can knock you out of the running for the house you already toured.
Lenders pull credit again near closing, and a fresh auto loan in that window has killed plenty of deals.
Another confusing piece is what counts as income.
Overtime, side gigs, and bonuses usually need a two-year history before lenders will count them.
Self-employed buyers often face the same waiting game.
If you're relying on money that just started showing up, underwrite your budget using only the income a lender will actually recognize.
The practical move: run the math before a loan officer does.
Pull your statements, list every minimum payment, and divide by your monthly pay before taxes.
If the result is above 43% without a mortgage payment included, you have work to do before shopping.
If it's below 36%, you're in strong shape.
Either way, knowing the number turns a vague anxiety into a to-do list.
Our take: DTI is one of the few parts of the homebuying process entirely within your control, and most buyers ignore it until it's too late.
Spend an hour with a calculator before you spend a weekend touring open houses.
Final Thoughts
The number you find won't just shape your loan — it'll tell you what you can genuinely afford to live with afterward.