Learn the formula and steps to manually calculate your weighted average share price.
A simple average treats all purchases equally, but a weighted average accounts for the quantity of shares bought at each price. This gives you an accurate cost basis for tax reporting and profit calculation.
To calculate the total average cost, you must multiply each purchase price by the number of shares bought at that price, sum those totals, and divide by the total amount of shares held. This provides your weighted average cost basis.
For each purchase, calculate: Price × Quantity = Total Cost
Add up all the total costs from step 1
Add up the total number of shares purchased
This gives you the weighted average cost per share
Yes! Use the formula: =SUMPRODUCT(prices, quantities) / SUM(quantities). However, our calculator is faster and handles commissions automatically.
Yes, your average cost changes with each transaction. When you buy more, recalculate using all purchases. When you sell, your remaining shares keep the same average cost (though total investment decreases).
Use our high-precision stock average calculator to get instant results including commissions and averaging down targets.
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