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Housing & Total Debt-to-Income Ratios

Compare monthly housing costs and total debt payments with gross monthly income using the 28% and 36% budgeting reference points.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Results are estimates for planning and education. Confirm rates, taxes, fees, and legal requirements with the relevant institution or a qualified professional before making a financial decision.

Formula and method

With gross monthly income of 5,000, housing costs of 1,400 and other monthly debt payments of 400, the housing ratio is 28% and the total debt ratio is 36%.

Housing ratio = monthly housing costs / gross monthly income; total debt ratio = (housing costs + other debt payments) / gross income

Worked example

Enter these known values and leave the other values blank.

Gross monthly income
5000 USD
Total monthly housing costs
1400 USD
Other monthly debt payments
400 USD
Front-end ratio
28 %
Total monthly debt payments
1800 USD
Back-end ratio
36 %

Assumptions and limitations

  • All amounts are monthly. Gross income is before taxes and deductions. Convert annual property tax and insurance to monthly amounts before entering them.
  • The principal field means the principal portion of a monthly payment, not the outstanding loan balance or original borrowed amount.
  • The component sum includes principal, interest, property tax and insurance only. Enter total housing costs directly if additional recurring housing charges should be included.
  • The 28% housing and 36% total-debt bands are budgeting reference points, not universal lender limits or a mortgage approval decision. Other affordability costs and lender rules are outside this calculation.
  • Debt ratios may exceed 100% when modeled payments exceed income. Zero housing or debt costs are valid.

Common questions

Should I enter the full mortgage balance?

No. Enter monthly payment amounts. The optional principal field is only the principal part of that monthly payment.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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