Mortgage vs Investments Calculator
Pay off mortgage or invest the cash?
Compare paying off mortgage early vs investing the same lump sum at expected return. Enter mortgage rate and investment return to see winner.
What this tool does
Enter lump sum, mortgage rate, investment return, and horizon. The tool shows the winner.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
50,000 lump sum vs 200,000 mortgage at 4% for 25 years: paying down saves 47,000+ interest. Investing 50k at 7% grows to 203,000 over 25 years — far more than the mortgage interest saved. Investing wins when expected return exceeds mortgage rate.
Run it with sensible defaults
Using lump sum of 50,000, mortgage rate of 4%, investment return of 7%, horizon of 25, the calculation works out to 138,079.82. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.
The levers in this calculation
The inputs — Lump Sum, Mortgage Rate, Investment Return, and Horizon — do not pull with equal force. The rate and the time horizon usually dominate — compounding means a small change in either reshapes the final figure more than a similar shift in contribution size. Test this by doubling one input at a time.
How the math works
Investment future value compared to total mortgage interest saved (approximated as compound growth at mortgage rate). The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".
Stress-testing the plan
Run the calculation at your current rate, then run it again at a rate 2–3 percentage points higher. That's roughly what a product reset could bring at renewal, and it's a useful check on whether you can afford the mortgage in a higher-rate world, not just today's.
What this doesn't capture
The figure excludes arrangement fees, valuation costs, legal fees, insurance, and any early-repayment charges — those can add several thousand to the headline cost. Rate changes at renewal for fixed-term deals will shift the picture further. Use this for the core interest/principal math and add the other costs on top.
Mortgage vs investments produces a winner based on the inputs provided.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Investment future value compared to total mortgage interest saved (approximated as compound growth at mortgage rate).
References
Frequently Asked Questions
Liquidity trade-off?
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Psychological value?
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