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Stock average calculator (average down)

Average cost per share = total amount paid ÷ total shares. Enter each purchase below to get your average price, then use the second part to find how many shares you would need to buy at today's price to bring your average down to a target.

Total shares–
Total cost–
Average cost per share–

Average down to a target

Shares to buy–
Cost of that purchase–
New average–

How to calculate your average stock price

Multiply each purchase's shares by its price, add the totals, and divide by the total number of shares. Example: 100 shares at $50 ($5,000) plus 100 shares at $40 ($4,000) = $9,000 ÷ 200 shares = $45 average.

How many shares to buy to average down

To reach a target average T when you hold S shares at average A and the price now is P (with P < T < A): shares to buy = S × (A − T) ÷ (T − P). The target must be between today's price and your current average.

Common questions

Does averaging down lower my loss?

It lowers your average cost, so the stock needs to rise less for you to break even, but it also increases how much money you have in that one stock if it keeps falling.

Do fees change my average price?

Yes. For tax cost basis, commissions are added to the cost. Add them to the price per share if you pay them.

Is average cost the same as cost basis for taxes?

Brokers usually track each purchase (tax lot) separately for capital gains. Average cost is mainly used for mutual funds; check how your broker reports basis.

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Last reviewed October 31, 2026. This calculator gives estimates for education and planning only. Results depend entirely on the numbers you enter and the assumptions stated on this page; they are not investment, tax or trading advice, and real results will differ.