Debt-to-Income Ratio Calculator
Your debt-to-income ratio is one of the first things mortgage lenders check. Too high, and you'll struggle to get approved — even with a good salary.
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Many mortgage applicants are surprised when their application is declined or they're offered a lower amount than expected. The most common reason? Existing debts that push their debt-to-income ratio above the lender's threshold.
Enter your income and monthly debt payments below to calculate your DTI ratio and see how lenders would view your application. We'll also show how much additional borrowing capacity you have before reaching the recommended 35% limit.
Debt-to-Income Ratio Calculator
See how lenders assess your affordability. A lower DTI ratio improves your mortgage prospects.
Monthly: £3,750
Monthly Debt Payments
Your Debt-to-Income Ratio
Overall DTI Ratio
33.3%
Good — comfortable position for most mortgage applications
Housing DTI (Front-End)
24.0%
Lenders prefer under 28%
Total Monthly Debt
£1,250
Additional Borrowing Capacity
£63/mo
To stay under 35% DTI
DTI Rating Scale
UK lenders typically use income multiples (4-4.5x salary) for maximum loan amounts, but also assess affordability using DTI-style stress tests. A DTI under 35% generally indicates comfortable debt levels for mortgage applications.
Understanding Debt-to-Income Ratios
Why DTI Matters for Mortgage Applications
Your debt-to-income ratio is one of the key metrics UK lenders use to assess whether you can afford a mortgage. Even if your income is high enough for the loan amount, existing debts that push your DTI above 40% can result in a declined application or force you into higher-rate products.
What Lenders Include as "Debt"
- Mortgage or rent payments
- Credit card minimum payments (even if you pay in full each month, some lenders use 3% of the balance)
- Car finance (PCP, HP, or personal loans)
- Student loan repayments
- Buy Now Pay Later commitments (increasingly checked)
- Child maintenance payments
Tips to Improve Your DTI Before Applying
Clear small debts first — even paying off a £50/month car loan improves your ratio. Avoid opening new credit accounts in the 3-6 months before your mortgage application. If you have unused credit cards with high limits, consider whether closing them would help (note: lenders may count the available credit limit, not just the balance).
Frequently Asked Questions
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