Stock Average Cost Calculator
Combine purchase history or plan an additional buy to see a weighted average cost, unused cash, and the price change required to break even.
This calculator tracks weighted average purchase cost and is not a tax-lot accounting tool.
Cost basis
Combine purchases or plan the next one
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Advanced settings
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How to use
From inputs to a result you can review
- Choose Quick Purchase Plan or Transaction History.
- Enter current holdings and a planned buy, or list each purchase with fees.
- Add a current price to see unrealized profit or loss and recovery percentage.
- Review the formula before using the result in a plan.
Known limitations
What this calculation does not know
- MVP handles purchases only; it does not process sales.
- FIFO, LIFO, specific-lot accounting, and tax rules are excluded.
- Market price is entered manually and is not a live quote.
- Fees are included only where entered.
Educational calculation only. This is not personalized investment, trading, or tax advice.
Formula reviewed
Report an error →Method version 1.0
Calculation logic reviewed against the published methodology and automated test cases. Last updated August 5, 2026.