Investment Growth Calculator
Project investment growth year by year, with contributions that can step up annually — see the full compounding schedule, not just the final number.
Please note: For information only, not investment advice. Projections assume constant rates; real markets fluctuate and capital is at risk.
What the Investment Growth Calculator does
Compounding rewards time more than amount. Contributions made early have decades to grow, which is why the balance curve steepens sharply in later years even when the contribution rate never changes.
Formula
Each period: Balance = Balance × (1 + periodic rate) + ContributionPeriodic rate = (1 + Annual return)^(1 ÷ Periods per year) − 1Contributions escalate by the growth rate at each anniversary
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Initial investment | selected currency | Optional | Accepts 0 or more. |
| Regular contribution | selected currency | Optional | Accepts 0 or more. |
| Contribution frequency | one of 4 options | Yes | — |
| Expected annual return | % | Yes | — |
| Time period | years | Yes | Accepts more than 0, up to 100. |
| Annual contribution increase | % | Optional | — |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Contribution frequency and Currency.
- Enter Expected annual return and Time period.
- Optionally add Initial investment, Regular contribution and Annual contribution increase.
- Select Calculate.
Worked example
$10,000 to start, $500 monthly, 7% return, 20 years, contributions rising 3% a year.
- Initial
- 10000
- Contribution
- 500
- Rate
- 7
- Years
- 20
- Increase
- 3
$358,042.47 from $171,222.25 contributed, so $186,820.22 — 52.2% of the final balance — is growth rather than deposits.
Frequently asked questions
Does increasing contributions each year help much?
Considerably. Raising contributions 3% a year in line with income adds meaningfully to the final balance without feeling like a bigger sacrifice.
What return should I assume?
Use a conservative figure and run a pessimistic case too. Planning on the historical average leaves no margin if the future disappoints.
Method and sources
Method. Period-by-period compounding: the balance grows at the periodic rate, then the contribution is added, with contributions optionally escalating each year.
Assumptions
- The return is constant every period, and contributions arrive on schedule at the point modelled.
- Returns are reinvested in full with no tax or dealing cost deducted.
Limitations
- A constant rate is the projection's biggest simplification. Real returns arrive unevenly, and sequence matters: the same average with losses early leaves less than with losses late, which a smooth curve cannot show.
- Whether contributions are modelled at the start or end of each period changes the result by roughly one period's growth.
- The figure is nominal. Over the horizons these projections cover, inflation is usually the largest single adjustment still to make.