Why does average cost matter?

It tells you your true break-even price across multiple purchases at different prices ("dollar-cost averaging"), which is what you compare against the current price to gauge your position’s overall gain or loss.

Stock Average Calculator

Investing

Calculate your weighted average cost basis across multiple stock purchases.

Display currency

Changing the display currency only changes the symbol shown — amounts aren't converted, since this tool doesn't use live exchange rates.

Buy price	Quantity

Weighted average cost

Total shares: 0

Total cost: $0

How this is calculated

Weighted Average Cost = Σ(price × quantity) ÷ Σ(quantity) across all buy lots entered.

Frequently asked questions

Why does average cost matter?: It tells you your true break-even price across multiple purchases at different prices ("dollar-cost averaging"), which is what you compare against the current price to gauge your position’s overall gain or loss.

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Calculate your profit or loss on a stock trade, including buy and sell fees.

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Calculate the capital gain or loss on an investment and whether it’s short- or long-term.

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Calculate a stock’s dividend yield from its annual dividend and current share price.