Stock Average Cost Calculator

Work out the average cost per share across several purchases at different prices.

About Stock Average Cost Calculator

The average is weighted by share count, so a large purchase at a low price pulls it down more than a small one. Comparing it with the simple average of the prices shows how much the weighting matters. Average cost is the break-even price and the basis for any capital gains calculation, so an unweighted average will give the wrong answer to both.

Formula

Stock Average Cost

Average cost = total amount invested ÷ total shares held

average cost: Share-weighted, not a simple average of the prices paid

Worked example

With the default values below, Stock Average Cost Calculator returns Average Cost per Share of $43.0909. Change any input above and every figure here is recalculated in your browser.

Inputs used

Shares in purchase 1minimum 0: 100
Price in purchase 1minimum 0: 50
Shares in purchase 2minimum 0: 150
Price in purchase 2minimum 0: 38
Shares in purchase 3minimum 0: 80
Price in purchase 3minimum 0: 44

Results

Average Cost per Share: $43.0909
Total Shares Held: 330
Total Amount Invested: $14,220.00
Break-Even Price: $43.0909
Simple Average of the Prices: $44.0000

Step by step

1Values used
2Stock Average Cost
3Average Cost per Share= 43.0909
4Total Shares Held= 330
5Total Amount Invested= 14,220.00
6Break-Even Price= 43.0909
7Simple Average of the Prices= 44.0000

Assumptions and limits

The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Stock Average Cost calculated?

Average cost = total amount invested ÷ total shares held The average is weighted by share count, so a large purchase at a low price pulls it down more than a small one. Comparing it with the simple average of the prices shows how much the weighting matters.

Why does Stock Average Cost matter?

Average cost is the break-even price and the basis for any capital gains calculation, so an unweighted average will give the wrong answer to both.

What values do I need to enter?

This calculator takes 6 inputs: Shares in purchase 1, Price in purchase 1, Shares in purchase 2, Price in purchase 2, Shares in purchase 3, Price in purchase 3. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.