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15-Year vs 30-Year Mortgage Calculator

Compare monthly payments and lifetime interest between a 15-year and 30-year mortgage at real rates.

15-year rates are typically 0.5–0.75% lower than 30-year rates — the calculator lets you set each independently.

$
%
%
15-year saves you
$308,420
In lifetime interest vs the 30-year option.
Monthly · 15 yr
$3,343
Monthly · 30 yr
$2,528
Total interest · 15 yr
$201,758
Total interest · 30 yr
$510,178
Monthly difference
$815
Interest saved (15 vs 30)
$308,420
Overview

How the 15 vs 30 Year Calculator Works

A 30-year mortgage is the default in the US, but a 15-year loan can save six figures in interest at the cost of a much higher monthly payment. This side-by-side comparison shows both numbers honestly so you can pick the term that matches your income stability and other goals.

Formula

The Math Behind the Calculator

For each term: Monthly = P × r / (1 − (1 + r)^−n). Total interest = (Monthly × n) − P. The 15-year typically uses a lower rate; enter both rates separately for an accurate comparison.

Example

A Worked Example

On a $400,000 loan: at 6.5% over 30 years, the payment is $2,528 and total interest is $510,178. At 5.85% over 15 years, the payment is $3,346 — about $818 more per month — but total interest drops to $202,357. The 15-year saves over $307,000.

How to use

How to Use the 15 vs 30 Year Calculator

  1. 1Enter the loan amount.
  2. 2Enter the 15-year rate and 30-year rate (15-year rates are usually meaningfully lower).
  3. 3Compare both monthly payments to your budget and decide whether the savings justify the higher payment.
Interpretation

What the Results Mean

  • Monthly difference is real cash flow you give up with the 15-year choice.
  • Total interest difference is what you save on the 15-year — but only if you actually stay in the home and don't refinance.
  • If the 15-year payment crowds out retirement contributions, the math may favor the 30-year plus investing the difference.
Avoid

Common Mistakes to Avoid

  • Using the same rate for both terms — 15-year rates are typically 0.5–0.75% lower.
  • Choosing a 15-year and then having no money left for emergencies or retirement.
  • Assuming you'll pay extra on a 30-year to mimic a 15-year — most people don't stick with it.
Keep going

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FAQ

Frequently Asked Questions

Which is better, 15 or 30?+

The 15-year saves more interest; the 30-year offers flexibility and lower required payments. Pick based on income stability and other financial goals.

Can I refinance from 30 to 15 later?+

Yes, and many homeowners do once income grows or rates drop.

What about a 20-year mortgage?+

Less common but available. It's a middle-ground compromise between 15 and 30.

Financial Disclaimer

This calculator is for educational and estimation purposes only. It does not provide financial, mortgage, tax, investment, or legal advice. Actual rates, payments, taxes, fees, insurance costs, eligibility, and loan terms vary by lender, location, credit profile, and market conditions. Always compare official offers and consult a qualified professional before making financial decisions.

Last updated June 2026 · Prepared by the mCalculator Editorial Team