15-Year Mortgage Calculator

What is a 15-year mortgage?

A 15-year fixed-rate mortgage is a home loan that you pay off in 15 years instead of the traditional 30. Because you're paying back the loan twice as fast, lenders charge a significantly lower interest rate — typically 0.50% to 0.75% lower than a comparable 30-year loan. On a $300,000 loan, that lower rate combined with the shorter term can save you well over $100,000 in total interest. The trade-off is a higher monthly payment, usually about 40% higher than a 30-year payment on the same loan amount and rate.

Why the discount exists: the balance comes back twice as fast, so the lender's money is exposed for 180 months instead of 360 and far less interest ever accrues — that is where the lower rate comes from. The product itself behaves like any fixed-rate loan: one payment amount for every one of the 180 months, no adjustment dates, and no prepayment penalty, so any lump sum you send goes straight to principal — useful when your income is lumpy even though the required payment is not.

The trade is simple to state and hard to fake: on a $300,000 loan at 6.0%, the payment is $2,531.57 instead of $1,798.65 — about 40% more cash each month — to finish 180 months sooner and pay $155,683 of total interest instead of $347,515.

How to use this calculator

1. Enter your loan amount (home price minus down payment).
2. Enter the interest rate — check the current 15-year rate from our mortgage rates page.
3. Confirm the loan term is set to 15 years.
4. Optionally include property taxes, homeowners insurance, and PMI for a full PITI payment.
5. Click Calculate to see your monthly payment, total interest paid, and total cost.

A realistic set of inputs for a $375,000 home with 20% down: loan amount $300,000, rate from today's market (the worked examples on this page use 6.0%), term 15 years or 180 months. For the optional PITI lines, budget property tax at roughly 0.9% to 1.2% of value a year — $281 to $375 a month on $375,000 — and homeowners insurance at $1,200 to $2,000 a year, which is $100 to $167 a month. Add HOA dues only if the property has them, and mortgage insurance only if you put down less than 20%: size that line with the PMI calculator and note the equity level at which it can be removed.

Understanding your results

The calculator outputs three core numbers: your monthly principal & interest payment, total interest paid over 15 years, and total cost of the loan. Compare the total interest to a 30-year loan on the same amount — the difference is your savings. You can also see the full amortization schedule, showing how much of each payment goes to principal vs interest and how your equity builds each year.

Two lines deserve the most attention. Total interest is what the loan costs above the amount you borrowed — $155,683 on a $300,000 loan at 6.0% over 15 years — and the calculator's total cost line adds it back to show $455,683 of cash leaving your account. The amortization schedule explains why that number is so much smaller than a 30-year loan's: by payment 60 you have already retired $71,973 of principal, and the interest share of each payment has dropped from 59.3% to 45.3%. The same schedule, worked one payment at a time, is the subject of the amortization guide.

Who should consider a 15-year mortgage?

A 15-year mortgage works best for borrowers who: have stable income that comfortably covers the higher payment, plan to stay in the home long-term, want to build equity faster, want to eliminate the mortgage before retirement, or are refinancing and have substantial equity. If you can't afford the higher payment without sacrificing other financial goals (emergency fund, retirement savings), the 30-year loan with optional extra payments may be a better fit.

There is also a lender-side filter, and it is mechanical: your debt-to-income ratios are calculated with the higher payment, so the same house on the same income can qualify on a 30-year and fail on a 15-year. Before you commit to the payoff date, run both payments through the debt-to-income calculator and confirm the 15-year version keeps your ratios inside your lender's limits with room to spare.

15-year vs 30-year: real example

On a $350,000 loan at 6.0% interest: a 30-year loan costs about $2,098/month and $405,000 in total interest. A 15-year loan costs about $2,954/month and about $181,600 in total interest. The 15-year saves roughly $224,000 in interest but adds about $855/month to your payment. This calculator lets you run your own numbers with your actual rate.

The comparison above holds the rate constant so the term is the only variable. In live quotes the 15-year usually prices 0.50% to 0.75% below the 30-year, which widens its advantage further — and the higher payment is the price of that advantage, so treat discomfort at the payment column as information: a schedule you cannot sustain through one bad year is not cheaper at any interest total.

How your 15-year payment is calculated

The payment comes from the standard amortization formula — the same one every fixed-rate mortgage uses — with one decisive difference: n is 180, not 360. Dividing the balance across half as many payments is what makes the payment high and the total interest low.

M = P × [ i (1 + i)ⁿ ] ÷ [ (1 + i)ⁿ − 1 ]

Here M is the monthly principal and interest payment, P is the loan amount, i is the monthly interest rate (annual rate ÷ 12), and n is the number of payments (180 on a 15-year loan).

Worked example: $300,000 at 6.0% for 15 years

Step 1: the monthly rate is 6.0% ÷ 12 = 0.005. Step 2: n = 15 × 12 = 180 payments. Step 3: the compounding factor is (1 + 0.005)¹⁸⁰ = 2.454094. Step 4: multiply and divide — 300,000 × 0.005 × 2.454094 = 3,681.14, and 2.454094 − 1 = 1.454094, so M = 3,681.14 ÷ 1.454094 = $2,531.57. Step 5: total repayment is $2,531.57 × 180 = $455,683, which makes lifetime interest $455,683 − $300,000 = $155,683.

Step 6 compares payment 1 with payment 180. In payment 1, $1,500.00 is interest and $1,031.57 reduces the balance — 41% of your first check builds equity, against roughly 17% on a 30-year loan at the same rate. After year 1 you have paid $17,654 in interest and the balance stands at $287,275. In the final year, interest totals just $965 across all 12 payments while $29,414 goes to principal, and the last payment is $12.59 of interest and $2,518.98 of principal.

Run your own scenarios

Three levers move the payment: rate, down payment, and term. First, rate — on a $300,000 loan over 15 years:

Half a point of rate is about $80 a month and roughly $14,700 of lifetime interest — which is why both terms should be quoted the same day, from the same lender, before you decide anything.

Second, down payment — on a $375,000 home at 6.0%:

Moving from 10% down to 20% cuts the payment by $316.45 a month and lifetime interest by $19,460 — the only lever here that also removes PMI. Check your price point in the down payment calculator.

Third, term: if $2,531.57 does not fit the budget, the 20-year mortgage calculator prices the middle option. At 6.0%, $300,000 over 20 years costs $2,149.29 a month with $215,830 of lifetime interest — $382.28 less each month than the 15-year, for $60,148 more interest.

How fast you build equity on a 15-year loan

Equity grows two ways: the down payment you start with, and every dollar of principal you repay. On a 15-year schedule the second engine runs twice as fast. Same $300,000 at 6.0%, both products side by side — the 30-year column holds the same rate so the term is the only variable:

After five years the 15-year borrower owns $71,973 of the house outright; the 30-year borrower owns $20,837 — a $51,136 difference in principal repaid after only 60 payments. After ten years that gap reaches $120,110. At year 15 the 15-year loan is simply finished: no payment, no balance, the property yours outright. The 30-year balance still stands at $213,147 with 180 payments ahead. Interest tells the same story from the other side: by year 15 the 30-year loan has burned $236,904 — more than the $155,683 the 15-year charges across its entire life.

Payment strain, debt-to-income, and when a 15-year is not worth it

Lenders judge the payment, not the virtue of the plan. Two ratios decide the approval: the front-end ratio, where principal, interest, taxes, and insurance divide into gross monthly income, and the back-end ratio, where every monthly debt divides into the same income. Common guidance is 28% front-end and 36% back-end; several lenders stretch to 43% or 45% back-end for strong files, and that stretch is exactly where payment strain hides.

Worked example: gross income $9,000 a month, non-mortgage debts $700, escrow (taxes and insurance) $500 on a $375,000 home. The 15-year PITI is $2,531.57 + $500 = $3,031.57 — 33.7% front-end and 41.5% back-end. The same house on a 30-year loan at 6.0% is $1,798.65 + $500 = $2,298.65 — 25.5% front-end and 33.3% back-end. Same borrower, same house, two very different files: one sits under both benchmarks, the other clears the front-end only by borrowing against the back-end.

One safety check belongs on every application: hold six months of the full PITI payment — $18,189 — in cash before choosing the shorter term, because the payment does not pause when income does.

Skip the 15-year when the budget only balances on your best-case income, when you are still carrying credit-card balances (clear those first), when the payment crowds out retirement contributions that earn an employer match, or when there is no emergency fund to absorb a job gap. In those cases the 30-year with a standing extra-payment habit keeps the interest lever in your hands without the fixed obligation. Size the comfortable price range first in the affordability calculator, then pick the term the leftover budget actually supports.

15-year mortgage strategy for 2026

1. Quote both terms the same day. The 15-year's rate advantage is a market convention, not a guarantee — it moves with lender appetite. Pull the 15-year and 30-year Loan Estimates side by side and compare three lines: monthly payment, total interest, total cost.
2. Price a point before you dismiss one. One discount point costs 1% of the loan — $3,000 on $300,000 — and typically buys about a quarter-point of rate: 6.0% to 5.75% lowers the payment from $2,531.57 to $2,491.23, a saving of $40.34 a month, so the point pays for itself in 74 months. Run your actual quotes through the mortgage points calculator and only buy if you expect to keep the loan past break-even.
3. If you already own a 30-year, consider switching tracks. Refinancing $300,000 from a 30-year at 6.5% into a 15-year at 5.9% raises the payment from $1,896.20 to $2,515.39 but cuts lifetime interest from $382,633 to $152,770. Closing costs run 2% to 5% of the new balance — $6,000 to $15,000 — so weigh the fee against the remaining interest drop and your debt-to-income limits. The refinance calculator maps the schedule month by month.
4. Keep an acceleration lane. A 15-year still allows extra principal: $200 a month on top of $2,531.57 retires the loan in 160 months — 13 years 4 months — and saves $19,408 of interest. Extra payments are optional, so they are the first thing to pause in a tight month, unlike the required payment. Model the instruction in the extra payment calculator.
5. Re-price the escrow every year. Counties reassess after a purchase and insurers re-rate annually, so the $500 escrow line above can drift up while the loan payment stays fixed. A $100 monthly increase adds 1.1 percentage points of front-end ratio on the same $9,000 income. Check the assessed value with the property tax calculator and shop the insurance renewal instead of accepting it.

Common mistakes with a 15-year mortgage

• Budgeting on best-case income. Commission, overtime, and year-end bonus are not salary. Qualify the payment against base income alone; treat variable pay as what funds lump-sum prepayment, not what covers the required installment.
• Making extra mortgage payments while carrying credit-card debt. $10,000 at 22% APR accrues about $183 of interest every month. Debt at 22% costs nearly four times what the 6.0% mortgage costs per dollar: clear the cards first, then point extra cash at the loan.
• Putting less than 20% down on the shorter term. PMI does not care about your term choice. Five percent down on the $375,000 example is a $356,250 loan at $3,006.24 a month plus PMI of about $208 a month — $3,214 of commitment before taxes and insurance ever appear. The 20% row in the table above removes that line entirely.
• Skipping the downside case. Approving the payment at your current income is only half the work. If income drops 15% to $7,650, the 15-year file above reaches 39.6% front-end and 48.8% back-end — past every common guideline — while the 30-year version sits at 30.0%. If the plan only works while nothing goes wrong, it does not work.
• Comparing quotes from different days or different point structures. Rate sheets move daily, and a rate bought down with two points is not comparable to a par rate. Line up both terms from each lender the same day, at the same points, before you do the subtraction.
• Cutting retirement contributions to afford the payment. An employer that matches 50% of your contributions returns 50 cents on every dollar you put in — immediately and guaranteed — while mortgage interest saved compounds quietly across 180 months. Fund the match first, then choose the term the remaining budget supports.

Frequently asked questions

Can I refinance a 30-year loan to a 15-year loan? Yes. Many homeowners refinance into a 15-year loan after building equity or when rates drop. Just be aware that refinancing resets the clock — make sure the total interest savings outweigh the closing costs.

Is the 15-year payment fixed? Yes, for fixed-rate loans. Your principal & interest payment stays the same for all 180 months.

Do I need a larger down payment for a 15-year? Not necessarily, but a larger down payment reduces the loan amount, which lowers the monthly payment on either loan type.

How much higher is a 15-year payment than a 30-year? On the same loan amount and rate, about 40% higher. A $300,000 loan at 6.0% is $2,531.57 a month over 15 years against $1,798.65 over 30 — and the 15-year pays $155,683 of total interest instead of $347,515.

Is a 15-year mortgage always better than a 30-year? No. It costs far less in total interest but requires a payment many budgets cannot sustain, and lenders calculate your debt-to-income ratios with that higher number. If the payment fits only on your best-case income, the 30-year with extra payments is the safer structure.

Can I make extra payments on a 15-year mortgage? Yes, and there is no prepayment penalty. An extra $200 a month retires a $300,000 loan at 6.0% in 160 months instead of 180 and saves $19,408 of interest — and because the extra is optional, it can be paused in a tight month.

How much down payment do I need for a 15-year loan? Conventional 15-year loans allow down payments as low as 5%, but below 20% you pay mortgage insurance on top of the higher payment. On a $375,000 home, moving from 10% down to 20% cuts $316.45 from the monthly payment and $19,460 from lifetime interest.

When does refinancing into a 15-year make sense? When the remaining interest savings comfortably exceed the closing costs — 2% to 5% of the new balance, or $6,000 to $15,000 on $300,000 — and the higher payment still fits your debt-to-income ratios after the move.

Related calculators

• 30-Year Mortgage Calculator — compare side by side
• Mortgage Calculator — full monthly payment with taxes & insurance
• 15-Year vs 30-Year Mortgage — full comparison guide
• Refinance Calculator — see if refinancing makes sense
• 20-Year Mortgage Calculator — the middle term priced out
• Amortization Guide — how every payment splits principal and interest