RevenueLab.fyi
Revenue Rex logo mark
💰 Financial · Rex's Toolbox

15-Year vs 30-Year Mortgage Calculator

See the payment gap, total interest saved, and how much faster you build equity.

Revenue Rex peeking

Rex says

Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.

Try a scenario

Click to load — tweak from there.

Inputs

Result

Interest saved with 15-year

$312,283

15-year monthly payment

$3,322

30-year monthly payment

$2,528

Extra monthly cost of 15-year

$793

Revenue Rex peeking

Psst — share this and help Rex grow

One click, a permanent link with your numbers baked in.

More financial

How to use this

  1. 1Enter loan amount ($).
  2. 2Enter 15-year rate (%).
  3. 3Enter 30-year rate (%).
  4. 4Read your interest saved with 15-year on the right — it updates as you type.
  5. 5Hit Share to keep the scenario or send it to someone.

About this calculator

The 15-year mortgage carries a lower rate and pays off in half the time but comes with a materially higher monthly payment. The 30-year keeps payments manageable and frees up cash flow that can be invested elsewhere. This tool compares monthly payment, total interest paid over the life of each loan, and the equity gap at any given year so you can weigh cash-flow flexibility against total interest saved.

FormulaPayment = P × r(1+r)^n / ((1+r)^n − 1). Total Interest = (Payment × n) − P. Equity gap compares remaining balance at a chosen year.

Worked example

Using the values the calculator loads with:

Inputs

  • Loan amount: 400000 $
  • 15-year rate: 5.75 %
  • 30-year rate: 6.5 %

Results

  • Interest saved with 15-year: $312,283
  • 15-year monthly payment: $3,322
  • 30-year monthly payment: $2,528
  • Extra monthly cost of 15-year: $793

What each field means

Inputs

Loan amount ($)
The loan amount used in the calculation, measured in $. Starts at 400000 $ so you have a working example on load.
15-year rate (%)
The 15-year rate used in the calculation, measured in %. Starts at 5.75 % so you have a working example on load. Accepted range: 0–15 %.
30-year rate (%)
The 30-year rate used in the calculation, measured in %. Starts at 6.5 % so you have a working example on load. Accepted range: 0–15 %.

Results

Interest saved with 15-year
Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
15-year monthly payment
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
30-year monthly payment
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Extra monthly cost of 15-year
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

Is the 15-year always the better deal?

Financially it almost always saves total interest, but only if the higher payment doesn't crowd out retirement saving, emergency funds, or higher-return investing.

Can I get the same benefit with a 30-year and extra payments?

Largely yes — pay a 30-year like a 15-year voluntarily and you capture most of the interest savings while keeping the lower required payment as a safety net in a bad month.

Why is the 15-year rate usually lower?

Lenders take on less risk over a shorter term, so 15-year rates typically run 0.4-0.75 points below 30-year rates.

Accuracy and limitations

  • Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
  • Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
  • This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.

Related tools

Pay Off Mortgage Early vs Invest Calculator

Compare guaranteed interest savings against expected market returns on the same dollars.

Extra Payment vs Invest Calculator

For any loan — auto, student, personal — see if extra principal or the market wins.

Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA
RevenueLab. (2026). 15-Year vs 30-Year Mortgage Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/mortgage-15-vs-30-year
HTML
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/mortgage-15-vs-30-year" target="_blank" rel="noopener">15-Year vs 30-Year Mortgage Calculator — RevenueLab</a> (2026).</p>
Markdown
Source: [15-Year vs 30-Year Mortgage Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/mortgage-15-vs-30-year) (2026).
What should I do?