Stock Average Price Calculator (Averaging Down)

Bought a stock, ETF or coin in several goes? This works out your average cost per share and, given the current price, the market value and the gain or loss. The average cost is not the average of the prices but total cost ÷ total shares: 10 shares at 70,000 and 30 at 60,000 average (700,000 + 1,800,000) ÷ 40 = 62,500, not the 65,000 halfway between the two prices.

The averaging-down section asks the reverse question: how many shares at today's price B bring the average to a target T? The answer is shares held × (current average − T) ÷ (T − B), rounded up because shares are bought whole. Holding 20 shares at an average of 65,000 and buying at 55,000 to bring the average to 60,000 takes 20 × 5,000 ÷ 5,000 = 20 shares, costing 1,100,000. It only works when the target lies between the current average and the purchase price; buying above the average to raise it (averaging up) uses the same formula.

The closer the target is to the purchase price, the faster the share count grows: in the example above a target of 56,000 needs 180 shares. Commissions, transaction taxes, exchange rates and capital gains tax are not included, and fractional quantities (fractional shares, crypto) are accepted. Inputs stay in this browser.