Investing regularly and letting returns compound is the most reliable way to build wealth. Over 30 years, the earnings often exceed the money you put in. Adjusting for inflation shows what the balance will actually buy.
How to use the Investment Calculator
- Initial investment
- Rate of return
- Term
- Compounding frequency
- Additional contribution
- Contribution frequency
- Contribution timing
- Annual inflation rate
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the initial investment, rate of return, term, compounding, regular contribution with its frequency and timing, and the inflation rate.
Inputs explained
| Field | What to enter |
|---|---|
| Initial investment | Amount in your currency |
| Rate of return | In % |
| Term | Units: years, months |
| Compounding frequency | Choose one: Yearly, Semi-annually, Quarterly, Monthly … |
| Additional contribution | Amount in your currency |
| Contribution frequency | Choose one: Monthly, Bi-weekly, Weekly, Quarterly … |
| Contribution timing | Choose one: End of each period, Beginning of each period |
| Annual inflation rate | In % |
What each result means
- Earnings = [Final balance] – [Total contributions]
- Final balance in today’s money = [Final balance]÷(1 + [Annual inflation rate]÷100)^[Term]
- Real rate of return = ((1 + effr([Rate of return]÷100, [Compounding frequency]))÷(1 + [Annual inflation rate]÷100) – 1)×100
Example values
How the main result changes when Initial investment changes and everything else stays at the example values above:
| Initial investment | Final balance |
|---|---|
| 5,000 | 271,648.6 |
| 7,500 | 285,962.14 |
| 10,000 | 300,275.69 |
| 12,500 | 314,589.24 |
| 15,000 | 328,902.78 |
| 20,000 | 357,529.87 |
Formula
Final balance = P × (1 + r ÷ m)^(m × t) + contributions growing at the matching periodic rate
Real value = final balance ÷ (1 + inflation)^t
Worked example
Inputs: Initial investment: $10,000; Rate of return: 7 %; Term: 25 years; Compounding frequency: Monthly; Additional contribution: $300; Contribution frequency: Monthly; Contribution timing: End of each period; Annual inflation rate: 2.5 %.
Results: Final balance = $300,275.69; Total contributions = $100,000.00; Earnings = $200,275.69; Final balance in today's money = $161,965.88; Real rate of return = 4.61 %.
Frequently asked questions
How much will my investment grow?
It depends on the return, time and contributions, and this calculator projects all three.
What return should I assume?
Many planners use 5–7% a year for a stock-heavy portfolio before inflation.
Why adjust for inflation?
A future dollar buys less; the real value shows your future purchasing power.
Sources
Guides on this topic
- How Does Compound Interest Work? Formula, Examples and the Rule of 72: Compound interest explained with real numbers: the formula, why compounding frequency matters, the rule of 72, monthly contributions over 30 years and how the same math works against you on debt.