Investment Calculator
Project your investment growth with compound interest. Add monthly contributions, choose compounding frequency, and see year-by-year returns.
How to use Investment Calculator
This investment calculator projects how a portfolio grows from an initial deposit plus ongoing contributions at an expected annual return. See the future value, how much came from your own contributions versus market growth, and an inflation-adjusted ("real") figure so you know what the balance is worth in today’s money. Use it to plan toward a target, compare contribution levels, or stress-test different return assumptions.
- Enter your initial investment amount.
- Add your regular contribution and its frequency.
- Set an expected annual rate of return.
- Choose the investment horizon in years.
- Review future value, contributions vs growth, and the projection chart.
Your data never leaves your device — 100% private processing.
Contributions versus market growth
Your final balance is the sum of everything you put in plus the compounded return on those dollars. In the early years contributions dominate; over longer horizons growth takes over and can exceed total contributions several times. Splitting the result this way (a contributions-vs-growth breakdown) shows why consistency over decades matters more than trying to time the market.
Returns, risk and realistic assumptions
Historical long-run stock returns are often cited around 7% real (after inflation), but actual returns vary widely year to year. Use a conservative rate for planning and remember projections are not guarantees. Account for fees — an expense ratio of even 1% compounds against you over decades and can cost a meaningful share of your final balance.
| Asset class | Approx. avg return | Notes |
|---|---|---|
| US large-cap stocks | ~10% | S&P 500 historical average |
| US stocks (real, after inflation) | ~7% | After ~3% average CPI |
| International developed stocks | ~8% | MSCI EAFE historical |
| US aggregate bonds | ~4–5% | Varies with rate environment |
| Cash / money market | ~2–3% | Near inflation over long run |
Worked examples
Index fund plan
Inputs: $5,000 + $500/mo · 7% · 25 yr
Result: ~$420,000 future value
Inflation-adjusted
Inputs: same, 2.5% inflation
Result: ~$227,000 in today’s money
Glossary
- Rate of return
- The annual percentage your investments are assumed to grow.
- Real return
- The return after subtracting inflation — your true gain in purchasing power.
- Contribution
- Money you add to the investment on a recurring basis.
- Expense ratio
- The annual fee a fund charges, expressed as a percent of assets.
Related reading
Frequently Asked Questions
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Why use Investment Calculator?
- Transparent formulas so you understand every calculation
- Supports multiple currencies and regional tax rules
- Saves you from spreadsheet errors with validated inputs
- Shareable results for discussions with advisors or partners
Common use cases
- Calculate how long to pay off a credit card balance
- Model different mortgage scenarios before house hunting
- Forecast investment growth with compound interest
- Break even analysis for a new product or service
- Compare net salary after tax across different countries
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