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Mortgage Affordability Calculator

Estimate UK mortgage affordability from household income, monthly expenses, interest rate, and term. Stress-test borrowing before applying.

Last reviewed 3 August 2026

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When to use this calculator

  • Before comparing mortgage products, brokers or repayment types.
  • When you want to test how a different deposit, rate or term changes the payment.
  • When you need a quick estimate before using a formal illustration or agreement in principle.
  • When you are stress-testing your budget against a higher rate.

A realistic Ireland planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic Ireland planning example
InputValue
Annual Income (€)€45,000
Monthly Expenses (€)6
Monthly Safety Buffer (€)6
Interest Rate (%)5%

After entering these figures, review payment-supported loan and mortgage payment budget together rather than in isolation. Then rerun the tool with one input adjusted.

How to read your results

Payment-Supported Loan

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Mortgage Payment Budget

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

This planning calculator converts the monthly payment left after the spending and safety buffer you enter into a loan amount at the selected rate and term. It does not use a lender income multiple and does not replicate underwriting. The output is a payment-supported ceiling based solely on your assumptions, not an amount a lender has assessed as affordable.

Real lenders review income, debts, dependants, regular spending, credit history, loan-to-value and the effect of future rate rises under their own policies. Include all ongoing commitments and keep a realistic buffer rather than allocating every spare pound to a mortgage. Obtain a decision in principle from a regulated lender or mortgage adviser before relying on a borrowing figure.

Common mistakes

  • !Mixing up loan amount and property value, which distorts affordability and LTV.
  • !Using a headline rate but forgetting fees, insurance or repayment type.
  • !Testing only one term length instead of comparing payment and total cost together.
  • !Treating the result as a lender decision rather than a planning estimate.

What to do next

  • Run a second scenario with a cautious assumption so you can see the downside clearly.
  • Compare the result with the related calculators below before making a decision.
  • Check current local rules, eligibility and provider terms before applying or committing money.
  • Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.

Frequently asked

It starts with monthly income less the expenses and safety buffer you enter, then estimates the loan that remaining payment could support over the selected rate and term. The result is a user-assumption planning ceiling, not a lender decision.

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