Mortgage Calculator

Companion guide: The Real Cost of Owning a Home

How to Use the Mortgage Calculator

Punch in the home price, your down payment, the loan term, and the interest rate. That's it. You get your monthly payment instantly, a principal-vs-interest split for every single month, and a full amortization schedule that shows how the balance drops over the life of the loan.

There's also a field for extra monthly payments. Plug a number in there and see what happens to your total interest and payoff date. The results are usually pretty dramatic.

Understanding Your Mortgage Payment

Here is something that catches a lot of first-time buyers off guard.

On a fixed-rate mortgage, your monthly payment stays the same for the whole loan. But what that payment is actually doing changes every month. Early on, most of it goes to interest. Like, an embarrassing amount. On a $300,000 loan at 6.5% over 30 years, your payment is roughly $1,896. Month one? About $1,625 of that is pure interest. Only $271 chips away at your actual balance.

By year 25 or so, the ratio has basically flipped. But those early years can feel like you're running on a treadmill — paying nearly two grand a month and barely making a dent in what you owe. Understanding this upfront saves you from a lot of frustration.

Choosing a Loan Term

The two big options:

• 30-year mortgage — lower monthly payment, way more interest over the life of the loan. Most people go this route because it keeps the monthly number manageable and gives you more breathing room in your budget.
• 15-year mortgage — significantly higher monthly payment, but you save an absurd amount on interest. Like, genuinely absurd.

Want numbers? A $300,000 loan at 6.5% costs you around $383,000 in total interest over 30 years. The 15-year version? About $172,000. That's $211,000 you do not pay to the bank. More than the original loan amount in savings. But your monthly payment jumps from $1,896 to roughly $2,613, so you need to be able to handle that.

How Amortization Actually Works

Amortization is the process of paying off a loan in scheduled installments. Every mortgage payment contains two parts: principal (the actual loan balance you're reducing) and interest (the fee for borrowing).

At the start of a 30-year mortgage, the bank applies most of your payment to interest because your outstanding balance is at its peak. Month by month, as the principal decreases, the interest portion shrinks and the principal portion grows. This is automatic — it's math, not something the lender decides.

The amortization schedule in this calculator shows every month: what you paid, how much went to principal, how much went to interest, and your remaining balance. Most people find it useful to look at Year 1 (discouraging — you're barely touching the balance), Year 10 (getting there), and Year 20 (finally making real progress).

The Power of Extra Payments

This is my favorite thing to show people. Even modest extra payments can knock years off your mortgage and save you tens of thousands.

An extra $100 a month on that $300,000 loan at 6.5%? You save over $52,000 in interest and you're done about five years early. A hundred bucks. That's a couple of streaming subscriptions and eating out one less time a week.

Some ways to make it happen:

• Round up the payment. $1,896 becomes $2,000. Simple, and you barely notice the difference.
• Biweekly payments — pay half your monthly amount every two weeks. Since there are 52 weeks in a year, that's 26 half-payments, which equals 13 full payments. One extra per year, almost by accident.
• Throw windfalls at it. Tax refund, work bonus, inheritance check — send it to the mortgage principal.
• One extra payment per year is the least you can do, and even that shaves years off a 30-year loan.

How Much Home Can You Afford?

The old guideline says keep your total housing costs — mortgage, insurance, property taxes — under 28% of your gross monthly income. And your total debt payments (housing plus car, student loans, credit cards) should stay under 36%.

So if your household brings in $7,200 a month before taxes, you're looking at roughly $2,016 max for housing. Work backward from there using this calculator to figure out what purchase price fits your budget. Be honest with yourself on this one. Banks will often approve you for more than you should actually borrow.

Common Mortgage Mistakes to Avoid

Buying at the top of your approved amount. Lenders approve you for the maximum they're willing to lend — not the maximum you should borrow. Getting approved for $450,000 doesn't mean a $450,000 house fits your budget. Factor in property taxes, insurance, HOA fees, maintenance, and your other financial goals before settling on a price.

Skipping the 15-year calculation. Many first-time buyers see the higher monthly payment on a 15-year mortgage and stop there. But the total interest difference is enormous. Run both scenarios in the calculator. Even if you go with the 30-year, it's worth knowing exactly what that flexibility costs you in interest.

Ignoring PMI. Private mortgage insurance kicks in when your down payment is less than 20%. It can add $100-200+ to your monthly payment and doesn't reduce your loan balance. Factor it into your affordability calculation.

Not shopping multiple lenders. Mortgage rates vary more between lenders than most people realize. A 0.25% difference on a $350,000 loan over 30 years is roughly $18,000 in total interest. Getting three or four quotes takes a few hours and could save you tens of thousands.

Frequently Asked Questions

What is included in a mortgage payment?

The real-world payment is usually more than just principal and interest. There's property tax, homeowners insurance, and possibly PMI rolled in too — lenders call it PITI (principal, interest, taxes, insurance). This calculator handles the principal and interest piece. You'll want to tack on estimated taxes and insurance to get the full picture of what you'll actually owe each month.

Should I put 20% down?

If you can swing it, 20% means you skip private mortgage insurance, which typically runs 0.5-1% of the loan amount per year. On a $280,000 loan that could be $1,400-$2,800 annually, just gone. But plenty of loan programs let you put down 3-5%, and for some people getting into the house sooner makes more financial sense than waiting to save up 20%.

Fixed rate vs. adjustable rate?

Fixed rate means your interest rate never changes. Predictable. Boring in the best way. Adjustable-rate mortgages (ARMs) start lower but can jump after the initial period — usually 5 or 7 years. This calculator assumes fixed rate. ARMs make sense in some situations but they add risk that most buyers don't need.

When should I refinance?

General rule: if you can drop your rate by at least 0.5-1% and you're planning to stay in the house long enough to recoup closing costs (usually 2-4 years), it's worth running the numbers. Plug your potential new rate into this calculator and compare.

How does making biweekly payments work?

Instead of 12 monthly payments, you make 26 half-payments per year — which equals 13 full monthly payments. That extra payment goes entirely to principal. On a 30-year loan, biweekly payments typically cut about 4-5 years off the payoff date. Just make sure your lender applies the extra payment to principal rather than holding it until the next due date.

What happens if I miss a mortgage payment?

Most mortgages have a 15-day grace period. After that, you'll typically owe a late fee (often 3-5% of the payment). After 30 days, the missed payment gets reported to credit bureaus. After 90+ days, the lender can begin foreclosure proceedings. If you're struggling, contact your lender proactively — most have hardship programs and would rather work with you than go through foreclosure.