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Guide

DTI calculation step by step

Debt-to-income (DTI) is a ratio of required monthly debt payments to gross monthly income. This guide shows a clean workflow for both front-end and back-end DTI so you can keep assumptions consistent across scenarios.

DTI topic hub DTI calculator What counts in DTI

DTI inputs to verify

  • Gross monthly income from documented sources.
  • Housing payment (PITI + HOA + PMI if applicable).
  • Required minimum payments for other debts.
  • Any lender-specific rules for student loans or deferred debt.

DTI formulas

  • Front-end DTI: housing payment / gross monthly income.
  • Back-end DTI: (housing + other required debts) / gross monthly income.
  • Use required monthly payments, not what you plan to pay.

Inputs checklist

  • Gross monthly income from pay stubs or tax documents.
  • Housing payment: PITI + HOA + PMI if applicable.
  • Minimum credit card payments from statements.
  • Installment loan payments from statements or credit report.

Step-by-step workflow

  1. Write down gross monthly income (stable, documentable).
  2. Add the full housing payment for the scenario you are testing.
  3. List required monthly debt payments (not balances).
  4. Calculate front-end DTI with housing only.
  5. Calculate back-end DTI with housing + other debts.
  6. Save the inputs so you can compare future scenarios.

Quick example

If gross income is $7,500/month and housing is $2,400, front-end DTI is 32%. Add $550 in other debt payments and back-end DTI is 39.3%. If the housing payment increases to $2,700, front-end DTI becomes 36% and back-end DTI rises to 43.3%.

Common mistakes to avoid

  • Using net income instead of gross income.
  • Using planned payments instead of required minimums.
  • Leaving out taxes, insurance, or HOA from the housing payment.
  • Mixing current housing payment with a future loan scenario.

How to use the calculator

Enter a single scenario, then change only one variable at a time. This keeps the comparison clean and shows which input is driving your DTI change. Save each input set as a baseline before testing the next change.

When to recalculate DTI

  • After a statement updates a required minimum payment.
  • After a payoff posts or a new loan is opened.
  • After you receive updated income documentation.
  • After taxes, insurance, HOA, or PMI estimates change.

References

Next steps

Recalculate DTI What counts in DTI Housing payment inputs Improve DTI

Educational use only. Not financial advice.

Last updated: 2026-02-17