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
Higher-value path
Invest
Investing path value
$173,019
Mortgage payoff path value
$92,813
Net worth difference
$80,207
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter extra monthly amount available ($).
- 2Enter mortgage rate (%).
- 3Enter expected investment return (%).
- 4Enter time horizon.
- 5Read your higher-value path on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Extra cash can either accelerate your mortgage payoff, guaranteeing a return equal to your mortgage rate, or go into the market for a historically higher but uncertain return. This calculator runs both paths with the same monthly amount over your time horizon — one reducing mortgage principal, the other compounding in an investment account — and shows the net worth difference at the end.
Worked example
Using the values the calculator loads with:
Inputs
- Extra monthly amount available: 500 $
- Mortgage rate: 6.25 %
- Expected investment return: 8 %
- Time horizon: 15
Results
- Higher-value path: Invest
- Investing path value: $173,019
- Mortgage payoff path value: $92,813
- Net worth difference: $80,207
What each field means
Inputs
- Extra monthly amount available ($)
- The extra monthly amount available used in the calculation, measured in $. Starts at 500 $ so you have a working example on load.
- Mortgage rate (%)
- The mortgage rate used in the calculation, measured in %. Starts at 6.25 % so you have a working example on load. Accepted range: 0–15 %.
- Expected investment return (%)
- The expected investment return used in the calculation, measured in %. Starts at 8 % so you have a working example on load. Accepted range: 0–20 %.
- Time horizon
- The time horizon used in the calculation. Starts at 15 so you have a working example on load. Accepted range: 1–30.
Results
- Higher-value path
- Returned as a plain value and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Investing path value
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Mortgage payoff path value
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Net worth difference
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Isn't investing always the mathematically better choice?
Only if your expected return exceeds your mortgage rate after taxes, and only if you actually stay invested through downturns instead of panic-selling — paying down debt has zero volatility risk.
Does this account for the mortgage interest deduction?
No — most homeowners now take the standard deduction, so the model assumes no meaningful tax benefit from mortgage interest. Adjust your effective mortgage rate down slightly if you itemize.
What about the psychological value of being debt-free?
That's real but not quantifiable here — many people rationally choose the lower-return path because eliminating a mortgage payment reduces required monthly expenses and stress.
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
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Pay Off Mortgage Early vs Invest Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/mortgage-payoff-vs-invest
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/mortgage-payoff-vs-invest" target="_blank" rel="noopener">Pay Off Mortgage Early vs Invest Calculator — RevenueLab</a> (2026).</p>
Source: [Pay Off Mortgage Early vs Invest Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/mortgage-payoff-vs-invest) (2026).