How to Calculate Your Average Stock Price After Multiple Purchases

When investors build a long-term position in a stock or ETF, they frequently buy shares in multiple installments over weeks, months, or years. Calculating your exact break-even cost basis requires computing a weighted average based on the number of shares bought in each trade.

Use the Burnjet Stock Average Price Calculator to combine up to multiple purchase tranches in seconds.

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The Weighted Average Formula #

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Step-by-Step: Using the Burnjet Average Price Calculator #

Step 1: Open the Tool #

Visit Burnjet Stock Average Price Calculator.

Step 2: Add Purchase Tranches #

Enter the share quantity and purchase price for your first order (e.g., 50 shares at $120).

Step 3: Add Subsequent Buys #

Click Add Buy Order to enter your second and third orders (e.g., 100 shares at $90 and 50 shares at$80).

Step 4: View Your Consolidated Cost Basis #

The calculator aggregates all orders to display:

• Total Shares Owned
• Total Capital Invested
• Weighted Average Price Per Share

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Worked Example: Averaging Down #

Suppose you accumulate shares of an index fund across 3 market dips:

• Buy 1: 20 shares at $100.00 =$2,000.00
• Buy 2: 50 shares at $80.00 =$4,000.00
• Buy 3: 30 shares at $70.00 =$2,100.00

Results: #

• Total Capital Invested: $2,000 +$4,000 + $2,100 =$8,100.00
• Total Shares: $20 + 50 + 30 = 100$ shares
• Weighted Average Price: $81.00 per share$ (8,100 ÷ 100 shares)

A simple average of the three prices ($100, $80, $70) would give$83.33, which is incorrect because you bought more shares at $80 and$70.

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Related Tools #

• Stock Return Calculator: Project exit returns based on your new average price.
• Stock Split Calculator: Adjust your cost basis after forward or reverse splits.
• Portfolio Allocation Calculator: Check overall asset diversification.