Stock Average Calculator
Enter each purchase lot's price and share count to find your average cost per share (dollar-cost averaging), plus your current gain or loss.
Purchase lots
| Price per share | Shares purchased |
|---|
Current price (optional)
Total shares:
Total invested:
Average cost per share:
Current value / gain-loss: ()
What "average cost" really means
Average cost per share is your total money invested divided by your total shares owned — it's a weighted average, not a simple average of the purchase prices, so buying more shares at a lower price pulls the average down more than buying fewer shares at that same price. This is the basis of dollar-cost averaging: investing a fixed amount on a regular schedule naturally buys more shares when prices are low and fewer when prices are high.
Frequently asked questions
Is dollar-cost averaging better than investing a lump sum? Historically, investing a lump sum immediately has often outperformed spreading it out, simply because markets tend to rise over time — but dollar-cost averaging reduces the risk of investing everything right before a downturn and can be easier psychologically.
Why is my average cost different from the current stock price? Your average cost reflects prices at the times you actually bought; the current price reflects today's market — the difference (positive or negative) is your unrealized gain or loss, shown here once you enter a current price.
Does this account for brokerage commissions? No — enter the effective price per share including any commission if you want the average cost to reflect total cost, since separate commission fields aren't included here.