But there's a quieter number that can sink a home loan application before a rate is ever discussed: your debt-to-income ratio, or DTI.
Lenders use DTI to measure how much of your monthly gross income goes toward debt payments.
Add up your expected mortgage payment — principal, interest, taxes, and insurance — plus minimum payments on credit cards, car loans, student loans, and any other installment debt.
Divide that total by your monthly pre-tax income.
That percentage is your DTI, and it often decides whether you get approved at all.
Today, many conventional loans allow up to 43%, and some government-backed loans push higher with compensating factors like strong credit or hefty reserves.
Cross that line and you're typically looking at a denial, a smaller loan than you wanted, or a demand for a bigger down payment.
Why it matters right now: with home prices still elevated and rates hovering well above the pandemic-era lows, buyers are stretching further.
A $2,000 monthly payment that felt comfortable in 2021 can now represent a much larger share of income.
Lenders see the same math and tighten up.
There are legitimate ways to improve your ratio before applying.
Paying down a credit card balance lowers the minimum payment, which lowers your DTI — even if you don't close the account.
Avoiding new car loans or financed furniture in the months before a mortgage application keeps the ratio clean.
And a larger down payment reduces the loan amount, which reduces the monthly payment.
If you co-sign a loan for a family member, that debt typically counts against your DTI, even if you never make a payment.
Same with authorized-user status on a credit card in some underwriting models.
Self-employed buyers and those with variable income should expect extra scrutiny.
Lenders often average two years of returns, and a single weak year can drag the calculation down.
Gathering documentation early can prevent surprises.
It's also worth knowing that DTI isn't the only gate.
Credit score, savings reserves, and employment history all factor in.
A high DTI with excellent credit and 12 months of reserves can sometimes still get approved.
A low DTI with a thin credit file might not.
The practical takeaway: run your own DTI before a lender does.
Plug your numbers into a calculator, be honest about every debt, and see where you land.
If you're above 43%, focus on lowering minimum payments rather than chasing a slightly better rate.
A lower rate on a loan you can't get approved for is worth nothing.
Our take: DTI is boring, unglamorous, and probably the single most useful number in the homebuying process.
Most buyers obsess over rate quotes while ignoring the ratio that determines whether they qualify in the first place.
Final Thoughts
Spend twenty minutes with a calculator before you spend weekends touring houses — it's the cheapest homework you'll ever do.