Mortgage Affordability Calculator 2026

How mortgage affordability works in the UK

UK lenders assess how much you can borrow using two main tests: an income multiple test and an affordability test. The income multiple sets a ceiling — typically 4 to 4.5 times your gross annual salary for sole applications, or 4 times combined income for joint applications. The affordability test then checks whether you could still afford repayments if interest rates were to rise by 3%, a requirement introduced by the Financial Conduct Authority.

Our calculator uses the standard income multiples and the annuity repayment formula to give you a reliable starting estimate. For a precise figure, speak to a whole-of-market mortgage broker who can assess your full financial picture.

Understanding loan-to-value (LTV)

LTV is the ratio of your mortgage to the property value, expressed as a percentage. A £200,000 mortgage on a £250,000 property is an 80% LTV. The lower your LTV, the less risk the lender takes on, and the better the mortgage rates available. Most lenders offer their best rates at 60% LTV. Products above 90% LTV are available but carry higher rates and stricter criteria.

Frequently asked questions

How much can I borrow for a mortgage?

Most UK lenders use income multiples to determine the maximum mortgage they will offer. For a sole applicant, the typical multiple is 4 to 4.5 times your annual gross income. For joint applications, lenders generally use 4 times combined income. However, affordability assessments — which take into account outgoings and stress-test rates — ultimately determine the offer, so actual borrowing may be lower. A mortgage adviser can help you understand what individual lenders will consider.

What is a good LTV for a mortgage?

LTV (loan-to-value) is the percentage of the property price you are borrowing. A lower LTV means better mortgage rates are available to you. An LTV below 80% generally unlocks a wider range of products, and an LTV of 60% or below typically attracts the most competitive rates. A 10% deposit gives you a 90% LTV, while a 40% deposit gives you a 60% LTV.

How is a monthly mortgage repayment calculated?

Monthly repayments on a capital repayment mortgage are calculated using the standard annuity formula: P × r ÷ (1 − (1 + r)^−n), where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. This ensures you repay both capital and interest in equal monthly instalments over the mortgage term.

What counts as income for a mortgage application?

Lenders consider a range of income sources including basic salary, guaranteed bonuses, regular overtime, commission, and self-employed profits (usually averaged over two to three years). Some lenders also consider rental income, investment income, and certain benefits. Most lenders will not count all income at 100% — for example, bonuses may be counted at 50%. A specialist mortgage broker can identify lenders most suited to your income profile.

Can I get a mortgage with a 5% deposit?

Yes. A 5% deposit gives you a 95% LTV mortgage. These products are available through the standard market and via the government-backed Mortgage Guarantee Scheme, which encourages lenders to offer 95% LTV products. Rates on 95% mortgages are higher than lower-LTV products, and lenders apply stricter affordability checks. First-time buyers with a 5% deposit may also benefit from shared ownership or First Homes schemes.

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