DTI Ratio
liveUnderstanding dti ratio
The Debt-to-Income Ratio Calculator is built around the same formulas your lender uses. Below is the math, in plain language, so you understand exactly what the numbers mean.
The core mortgage formula
Every amortizing mortgage payment follows the same equation: M = P × [r(1+r)n] / [(1+r)n − 1], where P is the principal loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. This formula produces a level payment that pays off the loan exactly over its term — front-loaded with interest, back-loaded with principal.
Why amortization matters
In the first year of a 30-year mortgage at 6.875%, roughly 86% of each payment goes to interest. By year 20, that flips — most of your payment is now retiring principal. Understanding this curve is the key to making smart decisions about extra payments, refinancing, and how long to stay in a home.
What this calculator includes
DTI is the number that makes or breaks a mortgage application. The 28/36 rule: housing costs under 28% of gross income, total debts under 36%. Some loan programs allow up to 43% or even 50% back-end. Every input updates the result in real time — no submit button, no page reload, no data sent anywhere.
DTI Ratio questions
What is a good debt-to-income ratio?
For mortgages, 36% back-end DTI is the conventional target. FHA allows up to 43% (sometimes 50% with compensating factors). VA caps residual income instead. Lower is always better for approval and rate.
What's the difference between front-end and back-end DTI?
Front-end DTI is just your housing payment (PITI) divided by gross monthly income. Back-end DTI adds all other debts — auto loans, student loans, credit cards, child support — to the housing payment.
How can I lower my DTI quickly?
Pay down credit cards, avoid new auto loans before applying, increase income with a side job, or choose a less expensive home. Paying off installment loans early helps less than lowering revolving balances.