Stock Average Calculator

Your average buy price (or cost basis) is the weighted average price you paid across every purchase of a stock, which becomes your effective break-even point. Investors track it closely when "averaging down" — buying more shares after a price drop to lower their overall average — a common but double-edged strategy that only pays off if the stock eventually recovers.

List each purchase lot's quantity and price. The calculator multiplies each lot's quantity by its price, sums those amounts to get your total money invested, and divides by the total number of shares to get your weighted average price — larger lots pull the average toward their price more than smaller ones.

Average = Σ(qty × price) ÷ Σ qty