Stock Average Calculator

This calculator takes a share position you already hold and a purchase you are adding to it, and returns the average cost per share afterwards. Enter the shares held and their average cost, then the shares and price of the new buy, and it gives the new average, the total invested, the position value at that price and the gain needed to break even. A second mode works backwards: it says how many shares at the current price would move the average to a figure you pick. Everything on the page is the arithmetic of a weighted average, so it describes a position rather than recommending one.

Calculator Type

Enter the position you already hold and the purchase you are making or considering. The new average is the total cost of every share divided by the number of shares, which is the only thing that moves it.

Shares You Already Hold *

Fractional shares are fine.

Average Cost per Share So Far ($) *

What your broker shows as the cost basis per share, not the price today.

Shares You Are Buying *

Price per Share on the New Buy ($) *

Commission or Fees on the New Buy ($)

Zero at a commission-free broker. Fees are part of the cost, so they raise the average.

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