How Much Mortgage Can I Afford? A Complete Guide for 2026

Buying a home is the most significant financial decision most people will ever make. But before you start browsing listings, the most critical question you must answer is: "How much can I actually afford?" In this guide, we'll break down the math behind mortgage affordability for both USA and UK residents.

1. The Golden Rule: The 28/36 Rule (USA Focus)

In the United States, lenders often use the "28/36 rule" to determine how much they are willing to lend you. This rule states that:

• Housing Ratio (28%): Your total monthly housing costs (principal, interest, taxes, and insurance) should not exceed 28% of your gross monthly income.
• Total Debt Ratio (36%): Your total monthly debt payments (including the new mortgage, car loans, credit cards, and student loans) should not exceed 36% of your gross monthly income.

If you earn $100,000 annually, your gross monthly income is $8,333. Under the 28% rule, your maximum mortgage payment would be approximately $2,333.

2. Understanding UK Lending Multiples

In the United Kingdom, affordability is calculated slightly differently. While lenders still look at your "take-home" pay and expenses, they primarily use a Salary Multiple. Most UK lenders will offer between 4 and 4.5 times your gross annual salary.

For a couple earning a combined £80,000, a typical maximum loan would be around £360,000. However, the Bank of England's affordability stress tests also ensure you could still afford the loan if interest rates were to rise by 3%.

3. Factors That Impact Your Affordability

Credit Score / Credit Rating

Your credit score is the single biggest factor in the interest rate you'll receive. In the US, a score above 740 is considered "excellent" and will net you the lowest rates. In the UK, while there is no universal "score," a clean credit history with Experian or Equifax is essential.

The Down Payment

The more you put down, the less you borrow. In the US, putting down 20% allows you to avoid Private Mortgage Insurance (PMI). In the UK, a larger deposit usually unlocks better "Loan-to-Value" (LTV) interest rate tiers.

Debt-to-Income (DTI) Ratio

Even if you have a high income, high existing debt can disqualify you. Lenders want to see that you have "breathing room" in your budget. If your DTI is over 43%, you may find it difficult to secure a conventional loan. You can calculate your ratio using our DTI Calculator.

4. Hidden Costs of Homeownership

Affordability isn't just the mortgage payment. You must also account for:

• Property Taxes / Council Tax: These vary wildly by location.
• Homeowners Insurance / Buildings Insurance: A mandatory requirement for lenders.
• Maintenance: A good rule of thumb is to set aside 1% of the home's value annually for repairs.
• Closing Costs / Stamp Duty: Expect to pay 2-5% of the purchase price in upfront fees.

5. How to Improve Your Affordability

If the numbers don't look the way you want them to, here are three steps to take before applying:

1. Reduce Existing Debt: Paying off a car loan can significantly increase your borrowing power.
2. Increase Your Credit Score: Check for errors on your report and ensure all payments are on time.
3. Save for a Larger Deposit: Even an extra 5% can drastically lower your monthly payment and interest rate.