Calculate your average cost per share when you've bought a stock at different prices over time. Add as many purchases as you need.
When you buy a stock multiple times at different prices, your average cost basis is the weighted average price per share across all your purchases. This number is crucial for calculating your true profit or loss and for tax reporting.
For example, if you buy 10 shares at $100 and 10 shares at $120, your average cost is ($1,000 + $1,200) ÷ 20 = $110 per share.
"Averaging down" means buying more shares when the price drops, lowering your average cost. If a stock drops from $100 to $80 and you buy the same dollar amount, your new average is $88.89 — much closer to breakeven. However, only average down on stocks you believe are fundamentally sound. Averaging down on a failing company just means losing more money.
Dollar cost averaging (DCA) automates this process — you invest a fixed amount regularly regardless of price. This naturally buys more shares when prices are low and fewer when high. Try our DCA Calculator to compare strategies.
Yes, most brokers automatically calculate and display your average cost basis. However, if you transferred shares between brokers, you may need to manually track your cost basis.
After a stock split, your average cost per share is divided by the split ratio. Use our Stock Split Calculator to see the adjusted price.
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