How Much Mortgage Can You Afford? (Simple Formula + Examples)

Buying a home is one of the biggest financial decisions most people make. A common question is:

How much mortgage can you actually afford?

The answer depends on several factors including your income, debt, interest rates, and down payment. Understanding these factors can help you avoid buying a home that stretches your budget too far.

In this guide, we’ll explain the main rules lenders use, show real examples, and help you estimate a realistic mortgage budget.

Try estimating your own numbers using the Mortgage Calculator →

What Determines How Much Mortgage You Can Afford?

Mortgage affordability depends on several financial factors. Lenders evaluate these to determine whether a loan is safe to approve.

The most important factors are:

Even small differences in these numbers can significantly change how much house you can afford.


The 28/36 Rule (The Most Common Mortgage Rule)

One of the most common guidelines lenders use is called the 28/36 rule.

This rule suggests that:

Example:
Monthly income = $6,000 If you already have $400 in car and credit card payments, your safe mortgage payment would be roughly: $1,760 per month

This rule helps lenders reduce the risk that borrowers will struggle to make their payments.


Understanding Debt-to-Income Ratio (DTI)

Another important number lenders use is the debt-to-income ratio (DTI).

This measures how much of your monthly income goes toward debt payments.

DTI formula:

Monthly Debt Payments ÷ Monthly Gross Income

Most lenders prefer a DTI below 36%–43%.

Example: Monthly income = $5,000 Monthly debt payments = $1,500 DTI = 30% This would usually be considered safe by lenders.

How Interest Rates Affect Mortgage Affordability

Interest rates have a huge impact on the monthly payment for a mortgage. Even a small change can significantly change how much home you can afford.

Example: $350,000 mortgage (30 years) Difference: $449 per month

Higher interest rates reduce how much home you can comfortably afford.

Learn more about how rates affect borrowing in What Is a Good Interest Rate in 2025?.


The Impact of Your Down Payment

Your down payment also affects your mortgage affordability.

A larger down payment reduces:

Example: $400,000 home The second scenario can reduce your payment by several hundred dollars per month.

Many lenders also require private mortgage insurance (PMI) if the down payment is below 20%.


Example: How Much House Can You Afford?

Let’s look at a realistic affordability example.

Example buyer: Using the 28% rule: Housing budget = $2,100/month At a 6.5% mortgage rate, this could support a loan of roughly: $330,000 – $360,000

Actual results vary depending on taxes, insurance, and loan terms.

Use the Mortgage Calculator to test different price scenarios.


Hidden Costs Many Buyers Forget

Many first-time homebuyers focus only on the mortgage payment. However, the true monthly housing cost usually includes several additional expenses.

These costs can add several hundred dollars to the monthly budget.

That’s why it’s important to look at the full housing cost, not just the loan payment.


Common Mistakes When Estimating Mortgage Affordability

Many buyers overestimate what they can safely afford.

Common mistakes include:

A mortgage that looks affordable on paper may still feel stressful if it leaves no room in your monthly budget.


How Mortgage Payments Are Calculated

Mortgage payments include several components:

You can learn more in the guide:

How Mortgage Payments Are Calculated


Tips for Choosing a Comfortable Mortgage Budget

Many financial planners recommend staying below the maximum allowed by lenders.

Consider these guidelines:

Buying slightly below your maximum affordability can provide valuable financial flexibility.


Final Thoughts

Determining how much mortgage you can afford is about more than just the home price. Your income, debts, interest rates, and down payment all affect the final monthly cost.

Using rules like the 28/36 guideline and running different scenarios with calculators can help you choose a home that fits comfortably within your budget.

Estimate your monthly payment:
Use the Mortgage Calculator to test different home prices, interest rates, and down payments.

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