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Calculate average cost across multiple purchases.
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Stock Average Calculator finds your true average buy price across multiple purchases of the same stock, a weighted average of total money invested divided by total shares, which is your real cost basis and break-even point.
The key insight is that it's weighted, not a simple average of prices. Because you typically buy different quantities at different prices, the larger lots pull your average toward their price. Buying 10 shares at $100 and 30 at $80 averages to $85, not $90, and that $85 is the number that actually matters for break-even.
It's the standard tool for 'averaging down', buying more after a price drop to lower your average cost. The calculator shows the new average clearly, but it's worth remembering that averaging down also increases your exposure to a stock that's already falling, so it's a risk decision, not just arithmetic.
Add a hypothetical lot to preview how a planned purchase would shift your average and break-even before committing. Everything runs in your browser, so your holdings stay private, and the output is an analysis aid rather than financial advice. Pair it with the Profit/Loss calculator to review outcomes.
| Price | Free, no signup, no paywall, no watermark |
|---|---|
| Works on | Any modern browser: desktop, tablet, and mobile |
| Processing | In your browser, files never leave your device |
| Account required | None |
| Category | Business Tools |
Enter each purchase as a price and quantity
Add as many lots as you have
See total shares, total invested, and the weighted average buy price
Add a hypothetical lot to see how it changes your average
Calculates your average buy price across multiple purchases of a stock
Add several buy lots at different prices and quantities
Shows total shares, total invested, and the weighted average price
Useful for averaging down or up positions
Runs in your browser, your holdings stay on your device
Free, with no signup and no limit on calculations
Finding your true average cost after buying a stock at several prices
Working out the new average if you average down on a falling stock
Checking the break-even price across all your lots
Planning an additional purchase to reach a target average
Your average cost is a weighted figure, quantity at each price matters, so don't eyeball a simple midpoint
Use a hypothetical lot to preview your new break-even before averaging down or up
Averaging down lowers your cost but raises your exposure to a falling stock, weigh the risk, not just the math
Common questions about this tool, its workflow, and what to expect before you use it.
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Calculate average cost across multiple purchases.
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