Total acquisition cost
Existing shares × existing price plus every additional quantity × purchase price.
078 · BUSINESS & FINANCE
Stock Average Cost Calculator
Combine existing shares and multiple additional buys by quantity-weighted average to calculate average cost, break-even reference, and target sell price.
LOCALCALCULATE IN YOUR BROWSER
LOCALShare quantities and purchase prices are calculated only in this browser and are not sent to or stored on a server.
Existing PositionEnter the shares already held and their current average acquisition price.
Additional BuysAdd multiple purchase lots. Each lot is combined by quantity-weighted average.
BUY 01
Display decimals
2
RESULT · Average-cost result
Reference assumes zero fees and taxes.Total Shares150
Total Cost1,400,000
Additional Shares50
Break-even Price9,333.33
Formula
Average Cost = Total Cost ÷ Total Shares = (1,000,000 + 400,000) ÷ 150Purchase summary#1 50 × 8,000Target Sell PriceAverage Cost × (1 + Return)
Target Sell Price10,266.67
HOW TO USE
How to use
- 01
Enter existing shares and their current average acquisition price.
- 02
Enter each additional purchase quantity and price, adding more rows when needed.
- 03
Review total shares, total acquisition cost, and the quantity-weighted average cost.
- 04
Use average cost as the zero-fee, zero-tax break-even reference.
- 05
Enter a target return to reverse-calculate the target sell price from average cost.
- 06
After calculating the new average cost, compare it with current price to see the move required to reach break-even.
WEIGHTED AVERAGE
Stock average cost guide
For multiple buys of the same stock, divide total acquisition cost by total shares instead of averaging prices directly.Total shares
Existing shares plus all additional purchase quantities.
Average cost
Total acquisition cost ÷ total shares gives the quantity-weighted average.
Break-even reference
The first release assumes zero fees and taxes, so break-even equals average cost.
Target sell price
Average cost × (1 + target return/100).
Separated roles
Current-price P/L stays in Tool 077 and dividend yield stays in Tool 079.
IMPORTANT NOTES
Important notes
- Average cost is a quantity-weighted average, not a simple average of purchase prices.
- Break-even is a reference that assumes zero fees and taxes.
- Current-price profit/loss is separated into Tool 077 and is not calculated automatically here.
- Dividends are separated into Tool 079 and are not applied to average cost.
- Live quotes, splits/consolidations, and portfolio analysis are outside the first release scope.
- This calculator is not investment advice.
- This is a simple average purchase cost excluding taxes, fees, dividends, and FX, so brokerage break-even can differ.
FAQ
Frequently asked questions
01What is the average after 100 shares at 10,000 and 50 at 8,000?+
Total shares are 150 and total cost is 1,400,000, so average cost is about 9,333.33.
02Can I simply average the purchase prices?+
No. Different quantities require a quantity-weighted average.
03What does break-even mean here?+
For the first release, it is the average-cost reference assuming zero fees and taxes.
04What is the sell price for a 10% target return?+
Average cost × 1.10. At 9,333.33 average cost, the target is about 10,266.67.