# Investment Calculator

URL: https://speedycalculator.com/calculators/finance/investment/
Last updated: 2026-10-25

> The investment calculator projects the growth of an investment with an initial amount, regular contributions, a rate of return and compounding – and shows the final balance, total contributions, earnings and the value in today's money after inflation.

## Inputs

- Initial investment
- Rate of return (%)
- Term (years, months)
- Compounding frequency
- Additional contribution
- Contribution frequency
- Contribution timing
- Annual inflation rate (%)

## Results

- Final balance
- Total contributions
- Earnings
- Final balance in today's money
- Real rate of return

## Formula

```
Final balance = P × (1 + r ÷ m)^(m × t) + contributions growing at the matching periodic rate
Real value = final balance ÷ (1 + inflation)^t
```

## Explanation

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.

### Tips

- Use the nominal annual rate and pick the compounding frequency your bank or broker states.
- Small differences in return or fees compound into large differences over decades.
- Run the calculation with a cautious, a central and an optimistic return to see the range of outcomes.
- Past returns do not guarantee future returns – nothing here is investment advice.

### Common mistakes to avoid

- Comparing an APR with an APY or effective rate.
- Ignoring inflation, taxes and fees when judging a real return.
- Entering a percentage as a decimal (5 instead of 0.05 is correct here).

### Inputs explained

FieldWhat to enterInitial investmentAmount in your currencyRate of returnIn %TermUnits: years, monthsCompounding frequencyChoose one: Yearly, Semi-annually, Quarterly, Monthly …Additional contributionAmount in your currencyContribution frequencyChoose one: Monthly, Bi-weekly, Weekly, Quarterly …Contribution timingChoose one: End of each period, Beginning of each periodAnnual inflation rateIn %

### 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 investmentFinal balance5,000271,648.67,500285,962.1410,000300,275.6912,500314,589.2415,000328,902.7820,000357,529.87

## 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 %.

## FAQ

**How much will my investment grow?**
It depends on the return, time and contributions – 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.

**What formula does the Investment Calculator use?**
Final balance = P × (1 + r ÷ m)^(m × t) + contributions growing at the matching periodic rate.


## Sources

- [U.S. SEC – Investor.gov compound interest and investing basics](https://www.investor.gov/)