Investment Calculator

Project an investment forward with regular contributions, and see it in real terms after inflation.

Please note: Projections are illustrative, not financial advice. Investment returns vary and past performance does not predict future results.

What the Investment Calculator does

This projects an investment forward from a starting balance plus regular monthly contributions. The inflation field converts the result into today's purchasing power, which is usually the number that actually matters for planning.

Formula

FV = P(1 + r)ⁿ + PMT × ((1 + r)ⁿ − 1) ÷ r
where r = expected annual return ÷ 12 and n = number of months
Real value = FV ÷ (1 + inflation)ᵗ
Real return = (1 + nominal) ÷ (1 + inflation) − 1

Inputs explained

Input	Unit	Required	Notes
Initial investment	selected currency	Optional	Accepts 0 or more.
Monthly contribution	selected currency	Optional	Accepts 0 or more.
Expected annual return	%	Yes	—
Investment period	years	Yes	Accepts more than 0, up to 100.
Inflation rate	%	Optional	Optional — shows the result in today's money.
Currency	one of 10 options	Optional	—

How to use it

Choose Currency.
Enter Expected annual return and Investment period.
Optionally add Initial investment, Monthly contribution and Inflation rate.
Select Calculate.

Worked example

$5,000 to start, $500 a month, 8% return, 25 years, 3% inflation.

Initial: 5000
Monthly: 500
Rate: 8
Years: 25
Inflation: 3

$512,214.08 nominally, or $244,636.30 in today's money after 3% inflation — $155,000 of that was contributed, the rest is growth.

Frequently asked questions

What return should I assume?

Historically broad equity indices have averaged roughly 7–10% before inflation over long periods, but no future return is guaranteed. Running a conservative and an optimistic case is wiser than picking one number.

Why does inflation matter so much?

At 3% inflation, prices roughly double every 24 years. A large nominal balance decades away buys far less than the number suggests.