Debt-to-income ratio calculator
Your debt-to-income ratio (DTI) is the percentage of your gross monthly income that goes toward recurring debt payments. Lenders scrutinise it when you apply for a mortgage, car loan, or personal loan because it measures how stretched your finances already are and how much room there is for a new payment obligation.
How it works
The formula is straightforward:
DTI = (total monthly debt payments ÷ gross monthly income) × 100
The key inputs are gross (pre-tax) income and the sum of all recurring debt obligations — not every monthly expense, just debt: mortgage or rent, car loans, student loans, personal loans, and the minimum required payment on each credit card. Grocery bills, utility bills, and subscriptions are not debt obligations and are excluded.
The tool then places the result into a standard lender band:
| DTI | Band | What it means |
|---|---|---|
| 28% or below | Excellent | Strong borrowing capacity |
| 29–36% | Healthy | Most lenders approve easily |
| 37–43% | Manageable | Approvable but options narrow |
| 44–49% | High | Compensating factors needed |
| 50%+ | Very high | Most conventional loans declined |
Front-end vs back-end DTI
Mortgage lenders often calculate two separate ratios:
- Front-end DTI (housing ratio): only the new housing payment divided by income. Most conventional lenders prefer this below 28%.
- Back-end DTI: housing payment plus all other debt payments divided by income. This is what this calculator computes, and the 36–43% range is the most common threshold.
When lenders quote a DTI limit they usually mean the back-end ratio.
Worked example
Monthly debt payments of £1,500 against gross monthly income of £5,000:
DTI = (1,500 ÷ 5,000) × 100 = 30% — Healthy band
Adding a new car loan with a £300/month payment would push the ratio to 36%, still within the healthy band but close to the threshold. If existing debts rose to £2,200, DTI would jump to 44%, into the high band where many lenders require compensating factors such as a larger deposit or strong cash reserves.
How to improve your DTI
Two levers move the ratio: lower debt or higher income. On the debt side, paying off the smallest balances first to eliminate minimum payments shrinks the numerator directly. Refinancing to a longer term or lower rate reduces the required monthly payment even if the balance does not change. On the income side, a second income, freelance work, or a raise all grow the denominator. Even a modest improvement can shift you across a lender threshold.
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