DCA Calculator

What dollar-cost averaging is

Dollar-cost averaging means investing the same amount of money at regular intervals regardless of price. Because the amount is fixed and the price is not, you automatically buy more shares when the price is low and fewer when it is high. This calculator takes your per-period amount and the price at each purchase, then shows how many shares you end up with, what they cost on average, and what the position is worth at the last price.

Why your average cost lands below the average price

average cost = total invested ÷ total shares

Buying a fixed dollar amount gives you the harmonic mean of the prices, which is always less than or equal to the arithmetic mean. That is a mathematical guarantee, not a market opinion: the only case where they are equal is when every price is identical. The more the price swings, the wider the gap.

Worked example — $500 a month for four months

Month	Price	Amount	Shares bought
1	$50.00	$500	10.000
2	$40.00	$500	12.500
3	$25.00	$500	20.000
4	$40.00	$500	12.500
Total	avg price $38.75	$2,000	55.000

Average cost is $2,000 ÷ 55 = $36.36, against an average price of $38.75. At the closing price of $40 the position is worth $2,200 — a 10% gain, even though the price ended 20% below where the first purchase was made.

What DCA does and does not do

It removes the need to pick an entry point, which is the part most people get wrong.
It lowers your average cost relative to the average price whenever prices move around.
It does not protect against a lasting decline. If the price keeps falling, you own more shares of something worth less.
In a market that rises steadily, investing everything at the start beats DCA — you simply bought earlier at lower prices.
Its real benefit for most people is behavioural: it turns investing into a schedule instead of a decision.

Lump sum or DCA

	Lump sum	DCA
Best when	Market rises from here	Market falls then recovers
Historically	Wins about two thirds of the time	Wins the rest
Worst case	Investing everything at a peak	Missing a sustained rise
Cash drag	None	Uninvested cash earns little
Emotional load	High — one big decision	Low — a repeated habit

Frequently asked questions

How many periods should I enter?

As many as you actually bought — add a row per purchase. Monthly for a year is twelve rows; the calculation works with any number.

Can I use different amounts each period?

Not in this tool — a fixed amount is what makes it dollar-cost averaging. For uneven purchases use the Stock Average Calculator, which takes a share count and a price per row.

Does it account for fees?

No. Subtract the fee from your per-period amount if your broker charges one, or add it to the price for a close approximation.

Weekly, monthly or quarterly — which is best?

The difference is small and shrinks as the period count grows. Monthly is the usual choice because it matches how people are paid.

Why is the gain calculated at the last price?

The final price you enter is treated as the current market price, so the value shown is what the whole accumulated position is worth today.

Is anything uploaded?

No. Every figure stays in your browser.

Note

This is a calculation tool, not investment advice. Past price patterns do not predict future ones, and no averaging method removes the risk of loss.