Invest vs Payoff Mortgage
Compare directing extra cash to investments versus using it to accelerate mortgage payoff.
Projection outlook
Follow how the balance builds over time as returns and new contributions compound together.
The path starts near $0 and ends around $126,785 by year 15.
Investing versus payoff comparison
Compare the projected value of investing the extra cash versus the estimated interest saved by using it for prepayments.
Principal vs interest breakdown
Review how much of the payoff goes toward reducing balance versus servicing interest.
Investment path is the largest component at about 67.9% of the total modeled amount.
Scenario comparison
Use the spread between scenarios to see how sensitive this outcome is to the assumptions you change first.
Optimistic currently leads conservative by about $44,447, which shows the approximate range across the modeled cases.
What changes the result most
Base
Invest minus payoff comparison
$66,770
Optimistic
Higher return case
$91,348
Conservative
Lower return case
$46,901
Accessibility summary: Extra mortgage payments may save about $60,015 of interest, while investing the same $400 monthly may grow to about $126,785. Base: $66,770 (Invest minus payoff comparison) | Optimistic: $91,348 (Higher return case) | Conservative: $46,901 (Lower return case)
Results
Investing the extra cash may grow to about $126,785 over 15 years.
Extra mortgage payments may save about $60,015 of interest, while investing the same $400 monthly may grow to about $126,785.
Investment value
$126,785
Mortgage interest saved
$60,015
Difference
$66,770
Extra monthly cash
$400
How to use this output
Start with the main result at the top. Then review the key numbers, look at how the chart changes over time, and compare the Base, Optimistic, and Conservative scenarios before making a decision.
Saved scenarios
Save multiple scenarios to compare optimistic, conservative, and custom planning paths later.
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Model overview
Understand the model at a glance
What this model does
- Shows how much interest you may save by paying extra toward the mortgage.
- Compares that with the projected future value of investing the same monthly cash flow.
- Helps frame the tradeoff between guaranteed debt reduction and uncertain market upside.
Key assumptions
- The investment side assumes a steady annualized return rather than real market volatility.
- The mortgage side assumes extra payments go directly to principal.
- Taxes on investment gains are not modeled in detail.
Example scenario
A household with a mid-5% mortgage and a solid emergency fund may be choosing between a guaranteed debt-reduction return and the possibility of stronger long-term investment growth.
How the math works
Open to review the formulas and planning logic behind this model.
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How the math works
Open to review the formulas and planning logic behind this model.
- The calculator runs one path with extra mortgage payments and one path that leaves the loan unchanged while investing the same extra cash instead.
- It then compares mortgage interest savings with the projected investment account value over the chosen horizon.
Next steps
Insights and recommendations
Questions
FAQ
Are these outputs guarantees?
No. They are planning estimates based on your assumptions and should be updated as markets, taxes, and spending change.
Do these calculators replace professional advice?
No. They are a strong planning starting point, but tax, legal, and investment decisions should be reviewed with a qualified professional when appropriate.
How often should I revisit my inputs?
A good rule is to revisit assumptions after major income, spending, family, tax, or market changes and at least a few times per year.
Why do the optimistic and conservative scenarios matter?
They help you see how sensitive the result is to assumptions instead of anchoring on one exact output.
Should I include inflation separately?
Yes when the calculator allows it. Separating inflation from returns usually makes the planning logic easier to understand.
What if my real life differs from the model?
That is normal. Use the output as a planning range and update the scenario as new information arrives.
Which metric should I pay attention to first?
Start with the headline summary and the first two or three result cards. Those usually hold the most decision-useful information.
Can I share these results with someone else?
Yes. Major calculators support shareable URL state so you can copy the scenario link and send it directly.