To calculate your debt-to-income ratio, add up your required monthly debt payments, divide that total by your gross monthly income, and multiply by 100. The result is the percentage of your pre-tax income already committed to debt, and it is one of the first numbers a mortgage lender checks. Most conventional lenders prefer that figure at or below 36%, though some programs allow ratios into the 40s or even 50s with compensating factors.
Here is the math with real numbers. Say your monthly debts are a $1,400 housing payment, a $350 car loan, a $150 student loan payment, and a $75 credit card minimum. That adds up to $1,975. Your gross monthly income is $6,500. Divide $1,975 by $6,500 to get 0.3038, then multiply by 100. Your DTI is about 30.4%.
What Counts as Monthly Debt
The numerator is every recurring obligation that would appear on a credit report or a court order. That means:
- Your housing payment: rent, or mortgage principal and interest plus property taxes, homeowners insurance, and any HOA dues.
- Auto loan payments.
- Student loan payments listed on your statement.
- Credit card minimums from your most recent statement, not the full balance and not what you actually pay.
- Personal and installment loan payments, including furniture financing and similar contracts.
- Court-ordered child support and alimony.
What stays out: groceries, utilities, health insurance premiums, cell phone bills, streaming subscriptions, and the rest of ordinary living expenses. Lenders exclude them because they vary and are not contractual debt. One-time bills and discretionary spending also do not count.1Fannie Mae. Debt-to-Income Ratios
How to Figure Gross Monthly Income
The denominator is your gross income, meaning everything you earn before taxes and deductions. For a salaried employee, divide annual salary by 12. If you are paid hourly, multiply your hourly rate by your typical weekly hours, multiply by 52, and divide by 12. Biweekly earners should multiply the gross paycheck by 26 and divide by 12, which accounts for the two extra paychecks a biweekly schedule produces each year.
Lenders will also count other income if it is stable and documented. Guaranteed bonuses typically need a 12-month history; discretionary bonuses usually need 24 months before a lender will average them in. Commission income generally requires two years of history, though some lenders accept one year if commissions make up less than 25% of total compensation. Social Security and pension benefits count with proof of the benefit amount. Rental income counts when it appears on tax returns, though lenders typically discount it by 25% to allow for vacancy and expenses.
Self-Employed Income
If you are self-employed, lenders want to see at least two years of history. The standard method is to pull net profit from Schedule C or the equivalent business return for each of the two most recent tax years, add the figures, and divide by 24. That produces a monthly average that smooths out year-to-year swings.2Fannie Mae. Self-Employment Income If your income dropped from one year to the next, some lenders weight the more recent year more heavily, which cuts the qualifying figure further.
Edge Cases That Change the Numerator
Deferred Student Loans
A deferred or forborne student loan is not ignored. For FHA loans, the lender uses 0.5% of the outstanding balance as your assumed monthly payment, so a $40,000 balance adds $200 to your debt column even if you owe nothing right now. Conventional programs are stricter, generally using 1% of the balance or the fully amortizing payment, depending on investor rules. A $60,000 deferred balance can add $300 to $600 to your monthly debts overnight.
Installment Debts Near Payoff
Some loan programs let you exclude an installment debt if it has ten or fewer remaining payments and the monthly payment is no more than 5% of your gross monthly income. A $350 car payment with eight payments left, against $8,000 of gross monthly income, meets both tests and can be dropped. Check every installment account on your credit report before applying, because this one rule can decide whether you qualify.
401(k) Loan Repayments
FHA guidelines treat 401(k) loan repayments as retirement contributions rather than debt, so they do not count against DTI under FHA’s minimum standards.3HUD. Section F Borrower Qualifying Ratios Overview Individual lenders can apply stricter overlays and count them anyway. Ask directly before assuming the payment will be excluded.
Front-End and Back-End: Two Numbers
Lenders look at two versions of the ratio. The front-end ratio, sometimes called the housing ratio, measures only your housing costs (principal, interest, taxes, insurance, HOA) against gross income. The back-end ratio stacks all your monthly debts, housing included, against gross income. When someone says “DTI” without further context, they almost always mean the back-end number. A common guideline is the 28/36 rule: housing below 28% of gross income, total debt below 36%.
Using the earlier example, the back-end ratio was 30.4%. The front-end ratio is $1,400 divided by $6,500, or about 21.5%.
Where Your Number Needs to Land
There is no single DTI cap that applies to every mortgage. Each loan program sets its own limits:
- Conventional (Fannie Mae): baseline maximum of 36%, stretching to 45% and in some cases 50% with strong compensating factors like a high credit score or substantial reserves.1Fannie Mae. Debt-to-Income Ratios
- FHA: standard back-end ceiling of 43%, front-end limit of 31%. With compensating factors, borrowers can qualify as high as 50%, and automated underwriting approvals sometimes reach 55%.3HUD. Section F Borrower Qualifying Ratios Overview
- VA: the guideline is 41%, but VA lenders weigh residual income heavily. Borrowers whose residual income exceeds the VA’s regional minimum by at least 20% often qualify above 41%.4VA. Debt-To-Income Ratio: Does It Make Any Difference to VA Loans?
Even when you can qualify at 45%, the 36% benchmark matters. Fannie Mae and Freddie Mac use loan-level price adjustments that can push your rate higher when DTI climbs above 40%. Over a 30-year mortgage, that fraction of a percentage point compounds into tens of thousands of dollars in extra interest. The old 43% figure still appears in a lot of online advice as a universal federal ceiling; it is not, though it remains the standard FHA back-end limit.
Lowering Your DTI Before You Apply
If your number is higher than you want, two levers move it: shrink the debt total or grow the income total. On the debt side, paying off a credit card entirely removes that minimum payment from the calculation. Paying down an installment loan to within ten payments of payoff may let you exclude it. Consolidating several debts into one loan with a lower combined payment helps the ratio even though the balance stays the same. Avoid opening new credit in the months before applying, because any new monthly payment goes straight into the numerator.
On the income side, documented overtime, a raise, or a side stream that shows up on tax returns all raise the denominator. Adding a co-borrower changes the ratio too, though their debts come along. For most people the fastest route is attacking the smallest debts first: wiping out a $200 monthly payment has exactly the same effect on DTI as earning an extra $200 in gross income, and paying off a small balance is usually quicker than engineering a permanent income increase.