Stock Average Calculator
Find your weighted average share cost.
How to use
- 1 Enter the number of shares and the price paid for your first purchase.
- 2 Click "Add lot" to record each additional purchase.
- 3 Read your weighted average price, total shares and total cost.
- 4 Copy the result for your records.
About Stock Average Calculator
The Stock Average Calculator works out the weighted average price you have paid for a stock when you have bought it across several separate transactions.
Investors who dollar-cost average, add to winners, or average down on a falling position quickly lose track of their true cost basis, and a simple mean of the prices is wrong because each purchase usually involves a different number of shares.
This tool does the maths correctly by weighting every price by the quantity bought in that lot.
Add a row for each purchase, type the number of shares and the price you paid, and the calculator immediately shows your average price per share, the total number of shares you hold, and the total amount invested.
You can add or remove lots freely, making it easy to model a new purchase before you place the order and see how it would move your break-even point.
Because My Tools Garage runs entirely in your browser, none of your trade details are uploaded or stored anywhere.
The figures stay on your device, the tool keeps working offline once loaded, and there is no account, tracking or limit on how many positions you calculate.
FAQ
Why not just average the prices?
A plain average ignores how many shares you bought at each price. The weighted average multiplies each price by its share count, giving your true cost basis.
Does this include brokerage fees or taxes?
No. It calculates the average from the share prices you enter. Add fees into a price if you want them reflected in your cost basis.