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Use the Compound Interest
Investment growth depends on starting amount, contributions, time and assumed return. The return assumption is the fragile part.
How much could my investment grow?
Estimate investment growth with compound interest, ROI, CAGR and the limits of return assumptions.
Assumptions to check
- Returns are estimates, not promises.
- Fees, taxes and inflation can reduce real outcomes.
- Volatile investments do not grow in a smooth line.
Quick checklist
- Enter starting amount.
- Add regular contributions if relevant.
- Compare more than one return rate.
- Check CAGR and ROI separately.
- Do not plan from the best-case result only.
Common mistakes
- Treating an average return as guaranteed.
- Ignoring fees and taxes.
- Comparing investments by final value without checking time and risk.
Why growth estimates need scenarios
Compound growth can make long-term numbers look powerful, but the answer depends heavily on the return rate. A small change in assumed return can produce a very different final value over many years.
How to use the calculator responsibly
Run a low, middle and high return scenario. The point is not to predict the future exactly; it is to see how sensitive the outcome is to time, contributions and return assumptions.
What to calculate next
Use ROI to compare simple gain, CAGR to annualize a start and end value, and Rule of 72 for a quick doubling-time estimate.