Mortgage rates get all the headlines, but there's a less famous number that can matter even more when you're trying to buy a home: your debt-to-income ratio.
Lenders use it to answer a simple question — after you pay your existing debts, how much room is left in your budget for a new house payment?
Get the math wrong and you can be pre-approved at one lender and turned down at the next.
Add up your monthly minimum payments: credit cards, car loans, student loans, personal loans, and any other installment debt.
Divide that total by your gross monthly income — the amount before taxes come out.
If you bring in $6,000 a month and owe $1,500 in minimum payments, your DTI is 25%.
Most conventional loans follow what's called the 28/36 rule.
Housing costs — principal, interest, taxes, and insurance — should stay under roughly 28% of gross income, and total debt including that housing payment should stay under about 36%.
In practice, many conventional lenders will approve borrowers up to 43% or even 45% with strong credit and savings.
FHA loans, which are popular with first-time buyers, often allow DTIs up to 43% and sometimes higher with compensating factors like a bigger down payment or cash reserves.
The catch is that a high DTI doesn't just disqualify you — it can shrink how much house you can afford.
Say you earn $6,000 a month and carry $800 in debt payments.
At a 43% ceiling, your total monthly obligations can't exceed about $2,580, which leaves roughly $1,780 for a mortgage payment including taxes and insurance.
Depending on rates and local property taxes, that might support a loan in the $200,000 to $250,000 range.
Carrying $400 more in monthly debt could knock tens of thousands off your maximum purchase price.
Paying down revolving balances is the fastest fix, because credit card minimums are calculated on the balance.
Wiping out a $5,000 card balance at a 2% minimum payment erases roughly $100 from your monthly debt load and can improve your ratio by a point or two — sometimes more if you carry several cards.
Paying off a small car loan entirely can be even more dramatic.
Lenders typically pull your credit and verify debts late in the process, so don't finance a new truck or open a store card while you're house hunting.
A single new $400 monthly payment can push a borderline application over the limit.
If you're self-employed or earn bonuses and commissions, ask whether the lender will count those income sources — documented, two-year histories often help.
One more thing worth knowing: DTI is not the only gate.
Lenders also weigh credit score, down payment, savings reserves, and employment history.
A 42% DTI with an 800 credit score and 20% down is a very different file than the same ratio with a 620 score and 3% down.
If one lender says no, another may say yes.
Our take: treat your DTI like a household budget metric, not a lender secret.
Check it once a quarter, attack the smallest balances first, and avoid new debt for at least six months before you apply.
Final Thoughts
The lower that number, the more options — and the less stress — you'll have when you finally make an offer.