Stock Average Calculator
Calculate your average stock price after multiple purchases.
Purchase #1
Purchase #2
What is it?
A Stock Average Calculator determines your average purchase price when buying shares of the same stock at different prices over time. This is especially useful when 'averaging down' after a price drop, or building a position gradually.
Formula
Average Price = Total Investment ÷ Total Shares
Formula Explanation
Each purchase contributes its own price × quantity to the total investment, and its own quantity to the total share count. Dividing the combined investment by the combined shares gives a weighted average — purchases with more shares influence the average more than smaller ones.
Example Calculation
Buying 100 shares at $150 and later 50 shares at $120 gives a total investment of $21,000 across 150 shares — an average price of $140.
How to Use
- Enter the price and quantity for each purchase you made.
- Add more purchases using the "Add Purchase" button if needed.
- Click Calculate to see your total shares, total investment, and average price.
Benefits
- Handles any number of purchases at different prices in one calculation.
- Shows total investment and shares alongside the average, not just the average alone.
- Useful for tracking cost basis across multiple buy transactions.
Use Cases
- Calculating your cost basis after averaging down on a stock.
- Tracking the true average price of a position built up over several purchases.
- Deciding whether further purchases would meaningfully change your average.
What Your Result Means
The average price is your effective cost basis per share across all entered purchases — useful for comparing against the current market price to gauge your unrealized profit or loss.
Tips
- Compare your average price to the current market price to quickly see your position's unrealized gain or loss.
- Remove purchases you entered by mistake using the Remove button before recalculating.
- Averaging down only makes sense if you still believe in the stock's fundamentals.
Common Mistakes
- Averaging down repeatedly on a stock whose fundamentals have genuinely deteriorated, rather than just its price.
- Forgetting to include brokerage or transaction charges, which slightly raise your true cost basis.
- Entering quantity and price in the wrong fields for a purchase row.
FAQs
What does "averaging down" mean?
It means buying more shares of a stock after its price has fallen, which lowers your overall average purchase price.
Is averaging down always a good strategy?
Not necessarily — it works well if the stock's fundamentals remain strong, but can increase losses if the price continues to decline for valid reasons.
Can I use this for more than two purchases?
Yes, you can add as many purchases as needed to calculate the combined average price across all of them.
Does this account for brokerage fees?
No, this calculates the average based on price and quantity only — add brokerage charges to your price per share manually if you want a fully loaded cost basis.
This calculator provides a simple estimate for informational purposes only and does not constitute investment advice.
Last updated: July 25, 2026