Debt-to-Income Ratio Calculator
Type your gross monthly income and your monthly payments: mortgage or rent, car loan, student loan, credit card minimum and any other debts. Leave a field blank if you have no such payment. The calculator divides all the payments by your income for the back-end DTI, and the mortgage or rent payment alone for the front-end DTI. Both are rounded to 2 decimal places. You also get a rating that places the back-end ratio against Fannie Mae's three caps.
How to use the Debt-to-Income Ratio Calculator
- Enter your numbers in the Debt-to-Income Ratio Calculator above.
- Press the Calculate button to see the result.
- To try other numbers, change any value and press the button again.
The DTI formula
Front-end DTI = Housing cost / Gross monthly income · · · Back-end DTI = All debt payments / Gross monthly income
Front-end DTI counts the housing payment alone. Back-end DTI counts every monthly debt payment. Different loans and lenders set different limits. Fannie Mae caps the back-end DTI at 36% for a manually underwritten loan, at 45% if the borrower meets its credit score and reserve requirements, and at 50% for a loan run through its Desktop Underwriter.
Worked example
Gross monthly income $8,000. Mortgage payment $2,000, car loan $400, student loans $300, credit cards $150. Front-end DTI: 2,000 / 8,000 = 25%. Back-end DTI: (2,000 + 400 + 300 + 150) / 8,000 = 35.625%, which the calculator shows as 35.63%. That is under the 36% Fannie Mae allows for a manually underwritten loan, so the rating reads "Up to 36%".
Frequently asked questions
What does the DTI rating mean?
It places your back-end ratio against the limits in Fannie Mae's Selling Guide, topic B3-6-02, read on November 3, 2026: 36% on a manually underwritten loan, up to 45% if the borrower meets the credit score and reserve requirements, and 50% on a loan run through Desktop Underwriter. Those limits apply to Fannie Mae loans. The limits it states are on the total ratio, so the rating reads only the back-end figure. It is not an approval or a denial, because a lender also looks at things this page cannot see. The exact ratio decides the band, so 36.004% prints as 36% and falls in the band over 36%.
Should I use gross or net income?
Gross. The CFPB defines DTI as your monthly debt payments divided by your gross monthly income, the amount you earn before taxes and other deductions. The calculator divides by whatever income you type, so a take-home figure gives a higher ratio than a lender would work out.
Does rent count toward DTI?
The calculator counts whatever you type in the Mortgage / Rent field in both ratios. For a Fannie Mae loan on the home you will live in, the housing payment in the DTI is the new loan's payment with taxes, insurance and HOA dues, not the rent you pay now.
How can I lower my DTI?
Pay down high-balance debts (especially credit cards), pay off small loans entirely (auto, personal), avoid taking on new debt before applying, and consider income from all sources (alimony, side work) if documentable.