{"tool":{"slug":"dti","name":"Debt-to-income ratio calculator","version":"2026-08-21","canonicalUrl":"https://carlo.finance/tools/dti","jsonUrl":"https://carlo.finance/tools/dti.json","pageUrl":"https://carlo.finance/tools/dti","parameters":[{"key":"income","label":"Annual gross household income","unit":"usd-per-year","min":0,"max":100000000,"default":100000,"sourceId":null,"help":"Before taxes, everyone whose income would go on the application. The default is an example, not a statistic."},{"key":"housing","label":"Monthly housing payment","unit":"usd-per-month","min":0,"max":1000000,"default":2000,"sourceId":null,"help":"Rent today, or the full house payment: principal, interest, tax, insurance, dues. The default is an example."},{"key":"debts","label":"Other monthly debt payments","unit":"usd-per-month","min":0,"max":1000000,"default":500,"sourceId":null,"help":"Minimum payments on cards, car loans, and student loans. Not utilities or groceries. The default is an example."}]},"inputs":{"income":100000,"housing":2000,"debts":500},"result":{"monthlyIncome":8333.33,"monthlyDebt":2500,"leftOver":5833.33,"frontEnd":0.24,"backEnd":0.3,"band":"within-36","lines":[{"pct":36,"label":"36%","meaning":"The manual-underwriting ceiling every program accepts.","allowed":3000,"headroom":500,"over":0},{"pct":45,"label":"45%","meaning":"Allowed with credit score and reserve requirements.","allowed":3750,"headroom":1250,"over":0},{"pct":50,"label":"50%","meaning":"The Desktop Underwriter maximum; not every borrower gets it.","allowed":4166.67,"headroom":1666.67,"over":0}],"maxHousingAt36":2500,"maxHousingAt45":3250},"drivers":[{"key":"income","label":"Income","step":5000,"pointsDelta":-1.43,"sentence":"Earning $5,000 more a year takes 1.43 points off the back-end ratio."},{"key":"debts","label":"Other monthly debt","step":-100,"pointsDelta":-1.2,"sentence":"Paying off $100 of monthly minimums takes 1.2 points off the back-end ratio."},{"key":"housing","label":"Housing payment","step":-100,"pointsDelta":-1.2,"sentence":"A housing payment $100 lower takes 1.2 points off both ratios."}],"sensitivity":{"byDebts":[{"debts":0,"backEnd":0.24,"headroomAt36":1000},{"debts":250,"backEnd":0.27,"headroomAt36":750},{"debts":500,"backEnd":0.3,"headroomAt36":500},{"debts":1000,"backEnd":0.36,"headroomAt36":0}],"byIncome":[{"income":75000,"backEnd":0.4,"frontEnd":0.32},{"income":90000,"backEnd":0.3333,"frontEnd":0.2667},{"income":100000,"backEnd":0.3,"frontEnd":0.24},{"income":110000,"backEnd":0.2727,"frontEnd":0.2182},{"income":125000,"backEnd":0.24,"frontEnd":0.192}]},"assumptions":[{"key":"income","label":"Annual gross household income","value":100000,"unit":"usd-per-year","provided":false,"source":null},{"key":"housing","label":"Monthly housing payment","value":2000,"unit":"usd-per-month","provided":false,"source":null},{"key":"debts","label":"Other monthly debt payments","value":500,"unit":"usd-per-month","provided":false,"source":null}],"sources":[{"id":"dti","name":"Fannie Mae Selling Guide B3-6-02, Debt-to-Income Ratios","url":"https://selling-guide.fanniemae.com/sel/b3-6-02/debt-income-ratios","asOf":"2025-04-02","note":"Manually underwritten loans: maximum total DTI 36%, up to 45% with credit score and reserve requirements. Desktop Underwriter: maximum 50%."}],"warnings":[],"disclaimer":"This compares your debt payments to your gross income the way a mortgage underwriter does, with the ratio limits Fannie Mae publishes. It is not a loan approval, a rate quote, or financial advice. Credit score, reserves, residual income, and program overlays change the real answer."}