Stock Average Price Calculator (Average Down)
Find your average cost per share across several stock purchases, your unrealized gain or loss, and how many shares to buy to reach a target average.
When you buy the same stock several times at different prices, your average cost per share is what tells you whether the position is up or down overall. Paste your purchases to get the weighted average price, total cost, and your unrealized gain or loss at today's price. You can also enter a target average to see exactly how many shares you would need to buy now to average down (or up) to it.
How to use this tool
- List each purchase on its own line: number of shares, then price per share, and optionally the fee.
- Enter the current share price to see market value and gain or loss.
- Optionally enter a target average price to find how many more shares to buy at the current price.
Formula
Average = Σ(shares × price + fee) ÷ Σ shares; shares to reach target = (C − T × S) ÷ (T − p)
C is your total cost, S your total shares, T the target average and p the current price. The target must lie between the current price and your present average, otherwise no amount of buying reaches it.
Example
With 100 shares at $50, 50 at $40 and 25 at $35, you paid $5,000 + $2,000 + $875 = $7,875 for 175 shares, an average of $45.00. At $38 the shares are worth $6,650, an unrealized loss of $1,225 (−15.56%). To bring the average down to $42 you would need (7,875 − 42 × 175) ÷ (42 − 38) = 131.25 shares, about $4,987.50 at today's price.
Frequently asked questions
Is averaging down a good idea?
It lowers your break-even price, but it also puts more money into a position that is falling. It makes sense only if your reasons for owning the stock still hold; the calculator shows the cost, not whether it is wise.
Does selling shares change my average cost?
Under the average-cost method, selling does not change the average price of the shares you keep; it only reduces the share count and total cost in proportion.
Is this the cost basis I report for taxes?
Not always. In the US, average basis is allowed for mutual fund shares and certain dividend reinvestment plan shares. Individual stocks are normally tracked lot by lot, first-in first-out unless you identify specific shares, so check your broker's cost-basis statement.
Should fees be included?
Yes. Commissions paid to buy shares are part of their cost, so including them gives a truer break-even price.
Sources
This tool gives an estimate for general information only. It is not financial, tax, legal or medical advice — check with a qualified professional before you rely on the result.
Last updated: 2026-10-30