What this calculator does

This UK-focused debt-to-income calculator compares the monthly housing and debt payments you enter with gross monthly income. It is useful as a personal planning ratio, but it does not predict whether a UK lender will approve a mortgage or other borrowing.

Formula used

Debt-to-income ratio equals housing payment, other monthly debt payments and any possible new payment divided by gross monthly income, multiplied by 100. The housing ratio uses the housing payment divided by gross monthly income.

How to read the result

A lower debt-to-income percentage means less of gross monthly income is committed to the payments counted here. UK mortgage lenders assess affordability using income, expenditure and their own lending criteria. Loan-to-income, or LTI, is a separate measure that compares the size of a mortgage loan with income, so it should not be confused with this monthly debt-to-income ratio.

Assumptions

  • Uses gross monthly income before tax and deductions.
  • Counts only the housing and debt payments entered.
  • Treats debt-to-income as a personal planning ratio rather than a universal UK lending threshold.
  • Does not include credit history, savings, dependants, living costs, interest-rate stress or individual lender policy.
  • Debt-to-income is different from the loan-to-income measure used in UK mortgage policy.

Sources and checks

Source links are included so you can check important formulas, thresholds and assumptions.

Frequently asked questions

How do you calculate debt-to-income ratio?

Add the monthly housing and debt payments you want to count, divide that total by gross monthly income, then multiply by 100. For example, GBP 1,500 of counted monthly payments and GBP 5,000 of gross monthly income gives a 30 percent debt-to-income ratio.

Do UK mortgage lenders use debt-to-income ratio?

UK lenders assess affordability using income, expenditure and their own lending criteria. Debt-to-income can be useful for personal planning, but it is not a universal UK mortgage approval threshold.

What is the difference between DTI and loan-to-income?

Debt-to-income compares monthly debt payments with monthly gross income. Loan-to-income compares the size of a loan, such as a mortgage, with income. They answer different questions and should not be treated as the same measure.

What debts should be included?

Include regular committed payments such as loans, credit cards, car finance, student loan payments where relevant and other borrowing payments you want the ratio to reflect.