Average Stock Price Calculator: Formula and Examples
Find the weighted average purchase cost per share across multiple trades.
How the calculation works
A weighted average accounts for how many shares were purchased at each price. Averaging the purchase prices alone is wrong when trade sizes differ. Tax-lot treatment depends on the applicable rules.
Average Stock Price formula
Average cost per share = sum(shares × price + purchase fees) ÷ total shares.
Worked example
100 shares at $50 and 50 shares at $60 cost $8,000 before fees. The weighted average is $53.3333 per share.
Inputs, assumptions, and interpretation
Purchase fees are included in the weighted cost. Fractional shares are supported. The arithmetic average cost is not a recommendation to buy or sell a security.
Displayed values are rounded, while calculations use unrounded numbers. The charts show modeled values rather than historical performance. For background, see Investor.gov introduction to investment returns.
Frequently asked questions
Does this result predict future returns?
No. The calculation summarizes the values entered. An illustrative chart or a historical return is not a forecast.
Why not average the purchase prices directly?
Each purchase price must be weighted by the number of shares. Larger trades have more influence on the average cost.
How should I interpret a negative result?
Some comparisons or value changes can be negative, including investment losses or a gap between alternative scenarios. Read the result labels to distinguish a balance from a change in value.