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Investment Calculator

See what a regular investment plan could build. Enter a starting amount, a monthly contribution, an expected annual return, and an inflation rate — the calculator shows the nominal future value, what that is worth in today’s money, and how much of the total is your own contributions versus growth. Results are estimates: they assume a fixed return and steady inflation, with no taxes, fees, or market ups and downs.

Starting amount ($)

Monthly contribution ($)

Expected annual return (%)

Annual inflation (%)

Years to invest

How it works

Each month the balance grows by the equivalent monthly rate and then the contribution is added. The monthly rate is derived from the annual return r as i_m = (1 + r)^1/12 − 1, so twelve months compound to exactly (1 + r). The inflation-adjusted value answers “what is this worth in today’s money?” by dividing the future balance by (1 + inflation)^years. Worked example: $5,000 to start, $200/month, 7% annual return, 3% inflation, 20 years. You put in $5,000 + (200 × 240) = $53,000; the balance grows to $120,855.70, of which $67,855.70 is growth; in today’s money that balance is worth $66,914.87. At year 5 the balance is $21,251.93 ($4,251.93 growth); at year 10 it is $44,046.10 ($15,046.10 growth) — growth accelerates because later years earn returns on earlier growth as well as on contributions.

Frequently asked questions

How is this different from the Compound Interest Calculator?

That calculator answers “how does a lump sum grow at a fixed rate, and how does compounding frequency change it?” This one is built around a regular plan: a monthly contribution as the main input, and an inflation-adjusted value so you can judge the result in today’s money. With no contributions, both agree: $10,000 at 5% for 10 years is $16,288.95 either way.

Why is the inflation-adjusted value so much lower?

Because 3% inflation for 20 years roughly halves purchasing power: $120,855.70 ÷ (1.03)²⁰ = $66,914.87. The nominal figure is what the account statement would show; the adjusted figure is what it would buy.

Is the expected return guaranteed?

No. Real investments fluctuate year to year, and a fixed 7% is a planning assumption, not a promise. The result is an illustration for comparing plans — for example, $200/month versus $300/month — not a forecast.

Are taxes and fees included?

No. Taxes on gains and fund fees both reduce the outcome, sometimes substantially over 20 years. Treat the growth figure as before taxes and fees.

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