Finance
Investment Calculator
Projects an investment balance from assumptions you supply, not a forecast.
Result
Projections use a constant annual return compounded monthly. Real markets do not behave that way, and sequence of returns matters enormously when you start withdrawing.
Get a Free Business AuditHow the calculation works
A starting balance plus periodic contributions, grown at an assumed annual return over a number of years, with fees deducted. Every figure the calculation produces is an arithmetic consequence of the assumed return, which is an input rather than a prediction.
What moves the number
- Assumed annual return, which dominates the result.
- Contributions and their frequency.
- Time horizon.
- Fees, which compound against the balance.
Where this one goes wrong
A steady annual return describes a path no market has followed, and the order in which good and bad years arrive affects the outcome where contributions or withdrawals are involved, which a smooth assumption cannot capture. Test a lower return and a worse sequence. This is arithmetic rather than financial advice, and anything involving actual money belongs with a licensed professional who can consider the whole situation.
Before you quote
- Test a materially lower return as well as the expected one.
- Model fees as an annual drag on the balance.
- Take advice from a licensed professional for real decisions.
Questions
About this calculator
What return should I assume?
Whichever you can defend, and then test a materially lower one. The output is an arithmetic consequence of the assumption rather than a prediction, so a single confident figure conceals how much rests on one input.
Why does a smooth return mislead?
Because no market has followed one. Where contributions or withdrawals are involved, the order in which good and bad years arrive changes the outcome, and a steady assumption cannot capture that at all.
Is this financial advice?
No. It is arithmetic on figures you supply and says nothing about what suits your circumstances, risk tolerance or alternatives. Those questions belong with a licensed professional who can see the whole picture.
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How to use this calculator
- Initial investment ($). Enter your own figure; the page starts at $25,000.
- Monthly contribution ($). Enter your own figure; the page starts at $750.
- Expected annual return (%). Enter your own figure; the page starts at 8%.
- Years invested. Enter your own figure; the page starts at 15.
- Inflation rate (%). Enter your own figure; the page starts at 2.5%.
The result updates as you type, so you can try a figure, see what it does to projected value, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Initial investment | $25,000 |
| Monthly contribution | $750 |
| Expected annual return | 8% |
| Years invested | 15 |
| Inflation rate | 2.5% |
What comes out
| Result | Value |
|---|---|
| Projected value main result | $342,202 |
| Value in today's money | $236,278 |
| Total contributed | $160,000 |
| Investment gain | $182,202 |
Projected to $342,202 after 15 years, worth $236,278 in today's purchasing power once 2.5% inflation is taken out.
How sensitive the answer is
Holding everything else steady and changing only initial investment, this is what happens to projected value. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Initial investment ($) | Projected value |
|---|---|
| $12,500 | $300,865 |
| $18,750 | $321,533 |
| $25,000 example above | $342,202 |
| $37,500 | $383,538 |
| $50,000 | $424,875 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Initial investment ($)
- A money amount, starting at $25,000.
- Monthly contribution ($)
- A money amount, starting at $750.
- Expected annual return (%)
- A percentage, between 0 and 100, starting at 8%.
- Years invested
- A number, between 0 and 80, starting at 15.
- Inflation rate (%)
- A percentage, between 0 and 50, starting at 2.5%.
What the results tell you
| Result | What it is |
|---|---|
| Projected value | The headline result. A money figure. |
| Value in today's money | A money figure. |
| Total contributed | A money figure. |
| Investment gain | A money figure. |
Rates and terms move
Loan and interest figures assume the rate and term you enter hold for the whole period. Variable rates, fees rolled into the balance and early-repayment terms all change the real cost.
Keep going
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