How Much House Can I Actually Afford?

The question everyone asks too late

In thirty years of financial planning, the most common regret I’ve heard from homeowners isn’t about the house they bought — it’s about the budget they set. Most people start by browsing listings, fall in love with a property at the top of their range, and then work backwards to justify the price. That’s the wrong order.

The right order is: know your numbers first, set a budget you’re comfortable with, and then go looking. This guide walks you through that process using four calculators that, together, give you a realistic picture of what you can afford.

Step 1: Check your debt-to-income ratio

Lenders use your debt-to-income ratio (DTI) to decide how much they’re willing to lend you. It’s a simple formula: your total monthly debt payments divided by your gross monthly income.

There are two versions:

• Front-end DTI: just your housing costs (mortgage, insurance, tax) divided by income. Most lenders want this below 28%.
• Back-end DTI: all your debts (housing plus car payments, student loans, credit cards, etc.) divided by income. Most lenders want this below 36%, though some will go to 43%.

Before you calculate what mortgage you can get, you need to know where your DTI stands right now. Use the Debt-to-Income Ratio Calculator to find out:

If your back-end DTI is already above 30%, you may want to pay down some debt before applying for a mortgage. Every dollar of monthly debt you eliminate increases the mortgage amount a lender will approve.

Step 2: Figure out your down payment

Your down payment affects everything: the loan amount, whether you’ll pay private mortgage insurance (PMI), and your monthly payment. The conventional wisdom of 20% down still holds as the gold standard because it eliminates PMI, but many buyers put down less.

Here’s the tradeoff: a smaller down payment gets you into a home sooner, but it increases your monthly costs and the total interest you’ll pay over the life of the loan.

Use the Down Payment Calculator to see how different down payment amounts change the picture:

A lesson I’ve learned from clients: don’t drain your savings to maximize the down payment. You need a cushion for closing costs (typically 2–5% of the purchase price), moving expenses, and the inevitable repairs that come with homeownership. I’d recommend keeping at least 3 months of living expenses in reserve after the down payment.

Step 3: Calculate how much house you can afford

Now that you know your DTI and down payment situation, the House Affordability Calculator pulls everything together. It takes your income, debts, down payment, interest rate, and local costs to estimate the maximum home price that keeps you in a comfortable financial position:

The number this gives you is a ceiling, not a target. Buying at the absolute maximum of what a lender will approve is how people end up house-poor — technically able to make the payment but unable to save, travel, or handle unexpected expenses.

My rule of thumb: aim for a home price that puts your total housing cost (mortgage, tax, insurance, maintenance) at 25% of your take-home pay, not your gross pay. Lenders calculate based on gross, but you live on net.

Step 4: See what your monthly payment actually looks like

The Mortgage Calculator lets you model specific scenarios. Plug in a home price from step 3, your expected interest rate, and your down payment to see the exact monthly breakdown:

Pay attention to the total interest over the life of the loan — it’s often eye-opening. On a 30-year mortgage, you’ll typically pay 60–80% of the original loan amount in interest alone. This is why even small rate differences matter, and why a 15-year mortgage (if you can afford the higher payment) saves an enormous amount.

The costs people forget

The mortgage payment is just the beginning. Factor in these ongoing costs before you commit:

• Property tax: varies enormously by location, from under 0.5% to over 2% of your home’s value annually
• Homeowner’s insurance: typically 0.3–1% of the home value per year
• Maintenance: budget 1% of the home value per year for upkeep (more for older homes)
• HOA fees: if applicable, these can add hundreds per month
• Utilities: often higher in a house than an apartment

A final thought

I refinanced my own mortgage twice over the years — once when rates dropped significantly and once when we shortened our term from 30 to 15 years after the kids finished college. Both times, I ran the numbers thoroughly before making the decision, and both times it paid off.

The best financial decision you can make in homebuying is to be boring about it. Run the numbers, set a realistic budget, leave room for life’s surprises, and buy something you can comfortably afford today — not something you’re hoping to grow into.