Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Future value
$300,851
Total contributed
$130,000
Earnings
$170,851
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter starting amount ($).
- 2Enter monthly contribution ($).
- 3Enter annual return (%).
- 4Enter years (years).
- 5Read your future value on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Future value of a starting amount plus monthly contributions, compounding annually.
Worked example
Using the values the calculator loads with:
Inputs
- Starting amount: 10000 $
- Monthly contribution: 500 $
- Annual return: 7 %
- Years: 20 years
Results
- Future value: $300,850.72
- Total contributed: $130,000.00
- Earnings: $170,850.72
What each field means
Inputs
- Starting amount ($)
- The starting amount used in the calculation, measured in $. Starts at 10000 $ so you have a working example on load.
- Monthly contribution ($)
- The monthly contribution used in the calculation, measured in $. Starts at 500 $ so you have a working example on load.
- Annual return (%)
- The annual return used in the calculation, measured in %. Starts at 7 % so you have a working example on load.
- Years (years)
- The years used in the calculation, measured in years. Starts at 20 years so you have a working example on load. Accepted range: 0–80 years.
Results
- Future value
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total contributed
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Earnings
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the investment calculator work?
Future value of a starting amount plus monthly contributions, compounding annually. The underlying maths is: FV = P(1+r)^n + PMT × ((1+r)^n − 1) / r, monthly compounded.
What do I need to enter?
4 values: starting amount, monthly contribution, annual return, and years. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the future value result mean?
It is returned as a money amount in US dollars and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
Who is this tool for?
It's built for anyone comparing money scenarios before committing — budgeting a payment, sanity-checking a quote, or seeing what a change in rate or term actually costs.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Investment Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/investment
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/investment" target="_blank" rel="noopener">Investment Calculator — RevenueLab</a> (2026).</p>
Source: [Investment Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/investment) (2026).