The Complete Guide to Mortgages

Before you fall in love with a listing, settle on a number you can actually live with. Lenders decide how much they'll lend using two debt-to-income ratios: a front-end ratio that caps your housing payment near 28% of gross income, and a back-end ratio that caps all your debt near 43%. They lend up to the lower of the two.

Here's the catch most buyers miss: those ceilings use pre-tax income and ignore the real cost of owning — maintenance, utilities, furnishing and the life you want to keep funding. The amount you can borrow is almost always more than the amount you should. A safer personal target is to keep total housing costs under 25–28% of your take-home pay while still saving 15% for retirement.

Four levers move your number, often by more than people expect:

• Income — the foundation everything scales from.
• Existing debt — a $400 car payment can cut your price by ~$60,000.
• Down payment — a larger one shrinks the loan and, at 20%, drops PMI.
• Interest rate — one point can swing your maximum price by tens of thousands.

Turn your real income and debts into a maximum price with the mortgage qualifier, then read how much house you can really afford for a full worked example.

A fixed-rate payment is the same total every month, but what's inside it shifts dramatically over time. Each payment covers the interest due that month plus a slice of principal. Early on, almost all of it is interest; only in the later years does most of it start paying down the balance. This front-loading is called amortization, and it's exactly why extra payments in the first decade save so much — every extra dollar of principal cancels years of future interest.

Your lender's quoted payment usually bundles in more than principal and interest. Property taxes and homeowners insurance are collected monthly through an escrow account and paid on your behalf, so the real figure — often called PITI — runs higher than the loan payment alone.

See the principal-versus-interest split on your own numbers, year by year, in the mortgage calculator.

Not every mortgage is the same product. The right one depends on your down payment, credit and situation. The big categories:

Conventional loans are the default for buyers with decent credit and a reasonable down payment. Government-backed loans (FHA, VA, USDA) exist to help specific buyers in — lower credit, smaller down payments, military service, or rural areas. Jumbo loans cover homes that exceed standard lending limits and come with stricter requirements.

Two structural choices shape your lifetime cost more than anything else. The first is the term. A 15-year loan carries a higher monthly payment but can save well over $100,000 in interest versus a 30-year on a typical balance, and usually comes with a lower rate. A 30-year keeps payments low and flexible. You can even take a 30-year and pay it like a 15-year for the best of both — see 15- vs 30-year mortgage.

The second is the rate type. A fixed-rate mortgage locks your payment for the life of the loan — predictable and the safe default. An adjustable-rate mortgage (ARM) starts lower but can reset higher after a few years, which only makes sense if you're confident you'll sell or refinance before it adjusts.

Finally, discount points let you pay cash upfront to buy down your rate — worth it only if you'll keep the loan long enough to recoup the cost.

You don't need 20% down to buy — many loans allow far less — but the size of your down payment changes two things. It shrinks the loan (so the same payment buys more house), and reaching 20% down avoids private mortgage insurance (PMI), a $100–$300/month charge that protects the lender, not you, until you reach 20% equity (an 80% loan-to-value).

Then there are the one-time costs at the closing table. Budget for these on top of the down payment — and don't drain your emergency fund to cover them:

• Closing costs — typically 2–5% of the price (lender fees, title, appraisal, taxes).
• Prepaid escrow — a few months of taxes and insurance upfront.
• Moving and setup — the costs that arrive the week you get the keys.

After you own it, plan on roughly 1% of the home's value a year in maintenance. Estimate the upfront bill with the closing cost calculator.

Lenders price your loan on risk, and your credit score is the biggest input — the gap between fair and excellent credit can cost tens of thousands over the loan. Before you shop, it pays to:

• Check and improve your credit score, especially by lowering card balances.
• Pay down other debts to improve your back-end ratio.
• Get pre-approved so you shop with a real budget and a stronger offer.

Once you have a mortgage, refinancing can lower your rate or payment — but it's only worth it when the monthly savings recoup the closing costs before you'd sell, and you don't reset the clock back to 30 years. The refinance calculator gives a clear break-even.

And to be mortgage-free sooner, send extra straight to principal, switch to biweekly payments, or refinance to a shorter term — after high-interest debt and your emergency fund are handled. See what each approach saves in how to pay off your mortgage early.