Stock Average Calculator
Calculate your average cost per share across multiple buys (averaging down or up), with total shares, total invested and break-even price. Free, private, instant.
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Find your average cost across buys
Buying the same stock at different prices over time leaves you with an average cost per share, and that single figure is what actually determines your profit or loss on the whole position. This calculator works out that average across all of your multiple buys, whether you have been averaging down as the price falls or averaging up as it rises, and it shows your total position size alongside.
Why the average cost is what matters
Your real gain or loss is always measured against your average cost, not against any single individual purchase price, so knowing that average is exactly what tells you where your true break-even point sits. Averaging down, buying more shares as the price falls, lowers your average and therefore your break-even; averaging up, buying as it rises, raises them both. The average is a share-weighted figure, which means a large purchase moves it considerably more than a small one at the same price. Seeing it computed across all of your buys tells you the precise price the stock must reach for you to move into profit.
Your true break-even
The calculation runs entirely in your browser, so your figures are never uploaded and stay on your own machine, which matters for anything involving money and personal finances.
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Frequently Asked Questions
How is average cost per share calculated?
As the total amount spent divided by the total shares bought across all purchases, a share-weighted average of the prices paid.
What is averaging down?
Buying more shares as the price falls, which lowers your average cost and break-even. Averaging up, buying as it rises, raises them.
Why does average cost matter?
Because your profit or loss is measured against it, not any single purchase. It tells you the price the stock must reach for you to break even.
Does a bigger buy move the average more?
Yes. The average is share-weighted, so a large purchase shifts it more than a small one at the same price.
Is this financial advice?
No. It is a calculation on your figures, not advice on whether to buy.
Privacy & Security
All processing happens locally in your browser — nothing is uploaded.
How to Use
Add a row for each purchase with its price and number of shares. The average updates live.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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