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Investment Calculator

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Project how a starting investment plus regular monthly contributions could grow over time at an assumed rate of return. This models steady, compounding growth — real markets move up and down, so treat the result as a long-term estimate, not a guarantee.

Investment Calculator

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Future value
$176,472
Total contributed
$77,000
Growth earned
$99,472
Assumes a steady monthly return — real investments fluctuate year to year.

The formula behind this projection

FV = P(1 + r)ⁿ + PMT × [((1 + r)ⁿ − 1) ÷ r]

P is your starting amount, PMT is your monthly contribution, r is the monthly return (annual rate ÷ 12 ÷ 100), and n is the number of months.

Example

Starting with $5,000, adding $300/month, at an assumed 7% annual return for 20 years: future value ≈ $176,472, of which $77,000 was contributed and about $99,472 came from investment growth.

Step-by-step guide

  1. Enter your starting amount — use 0 if you're starting from scratch.
  2. Enter your monthly contribution.
  3. Enter an expected annual return. A long-run diversified stock index has historically averaged roughly 7–10% before inflation — but future returns are never guaranteed.
  4. Enter your time horizon and compare the contributed total against the projected growth.

Common mistakes

Treating the projected return as guaranteed — real investments experience years of losses as well as gains, and this model smooths that out into a single steady rate.
Ignoring inflation — a dollar in 20 years buys less than a dollar today, so consider looking at the "real" (inflation-adjusted) return as well.

Frequently asked questions

What return rate should I use?

There's no single right answer — it depends on your investment mix. Many long-term planners use a conservative estimate rather than the best historical years, and running the numbers at a couple of different rates (e.g., 5% and 8%) gives a useful range.

Does this account for taxes or fees?

No — this is a pre-tax, pre-fee projection. Investment account fees and any taxes on gains will reduce your real, spendable future value below this estimate.

Is this the same as a retirement calculator?

The underlying math is the same, but our Retirement Calculator frames the inputs around your current and target retirement age, which some people find easier to plan with.

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