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Index Fund Calculator

Project the future value of an index fund from a lump sum and monthly contributions, net of the expense ratio.

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The Index Fund Calculator turns Initial investment, Monthly contribution, Years, Expected annual return, Expense ratio into Future value, Total invested, Total gain, instantly and for free. For instance, with Initial investment = 1,000, Monthly contribution = 200, Years = 20, Expected annual return = 7% and Expense ratio = 0.2% it returns Future value = $105,572.98, Total invested = $49,000.00 and Total gain = $56,572.98.

How to use it

  1. Enter your values: Initial investment, Monthly contribution, Years, Expected annual return, Expense ratio.
  2. Read the result instantly: Future value, Total invested, Total gain.

Frequently asked questions

What does the Index Fund Calculator actually compute?

It takes Initial investment, Monthly contribution, Years, Expected annual return and Expense ratio and derives Future value, Total invested and Total gain from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

5 values: Initial investment, Monthly contribution, Years, Expected annual return (%) and Expense ratio (%). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Initial investment = 1,000, Monthly contribution = 200, Years = 20, Expected annual return = 7% and Expense ratio = 0.2%, the calculator returns Future value = $105,572.98, Total invested = $49,000.00 and Total gain = $56,572.98. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Initial investment = 2,000, Monthly contribution = 400, Years = 40, Expected annual return = 7.7% and Expense ratio = 0.22% instead, Future value goes from $105,572.98 to $1,242,133.67 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which units should I enter the values in?

Enter Expected annual return % and Expense ratio %.

What does it give for smaller values?

Scaled down to Initial investment = 0, Monthly contribution = 0, Years = 1, Expected annual return = 6.3% and Expense ratio = 0.18%, Future value comes out at $0.00. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Comparing two investments that pay at different times, deciding whether a project clears its cost of capital, and sanity-checking a valuation someone else produced.

What is the most common mistake?

Trusting a valuation without asking what share of it comes from the terminal value. Past 70%, the answer is an assumption about the distant future dressed up as a calculation.

What is the difference between the Index Fund Calculator and the Fund expense ratio cost calculator?

This one returns Future value and Total invested; the Fund expense ratio cost calculator returns Annual fee and Total fees over period. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Mutual Fund Calculator is the closest one after this: Project a fund with a net-of-fees return, an optional front-end load and rising contributions.

Further reading

All guides →
ExplainerWhat Is an Index Fund? How Passive Investing WorksAn index fund tracks a whole market instead of betting on winners. Learn how tracking works, why diversification and low fees matter, and how it stacks up against active funds.ExplainerWhat Is Dividend Yield? Formula, Examples and TrapsDividend yield sounds simple — dividend divided by price — but a high number can be a warning sign. Here is how to read it and why total return matters more.ExplainerWhat a 1 Percent Fee Costs Over 30 YearsA one-point difference in annual charges turns $75,063 into $57,435 on the same $10,000. The fee costs more than the sum invested — here is why compounding does that.ExplainerDollar-Cost Averaging: What It Actually Buys YouSpending a fixed amount each period buys more units when the price is low, so your average cost is the harmonic mean of the prices while the average price is the arithmetic mean — always lower, by 4.10 percent on the path worked through here. Against a lump sum, a 200,000-path simulation puts DCA's standard deviation 41 percent lower and its expected terminal wealth $337 lower on $12,000.ExplainerPresent Value vs Future Value: Why Money in Thirty Years Is Worth About an Eighth of Its FacePV = FV ÷ (1+r)^n. At 7 percent over 30 years the discount factor is 0.131, so a promise of $100,000 in thirty years is worth $13,137 today — and $41,199 if you assume 3 percent instead.ExplainerWhat Is Slippage in Crypto? Price Impact, Tolerance and What It CostsPrice impact is arithmetic: on a constant-product pool it equals your trade size divided by the reserve plus your trade. Here is the formula, a table of trade size against impact, and why the setting called slippage tolerance changes none of it.