Stock Average Calculator
Calculate your new weighted average price per share after additional purchases. Includes trading commissions for accurate break-even analysis.
Current Holdings
New Purchase
About
Professional traders and long-term investors frequently adjust open positions by purchasing additional shares at different price points. This strategy, often called "averaging down" (if buying lower) or "averaging up" (if buying higher), alters the cost basis of the portfolio. Accurate calculation of this new average is critical for determining the true break-even point and setting appropriate stop-loss or take-profit orders.
Ignoring trading fees and commissions can lead to a distorted view of profitability. A raw weighted average might suggest a position is profitable, while the inclusion of execution costs reveals a net loss. This tool computes both the gross weighted average and the net average cost, providing a precise figure for the price per share required to exit the position without a loss.
Formulas
The core calculation is a weighted arithmetic mean. To find the new average price Pavg, the total value of the old holdings is added to the total value of the new purchase, divided by the total share count.
To incorporate trading costs (Commissions C), the formula adjusts to reflect the Net Average Cost:
Reference Data
| Scenario | Old Avg $ | New Buy $ | Shares Ratio | Outcome |
|---|---|---|---|---|
| Averaging Down | 100.00 | 80.00 | 1:1 | New Avg: 90.00 (Significant reduction) |
| Averaging Down | 100.00 | 80.00 | 10:1 | New Avg: 98.18 (Minimal impact) |
| Averaging Up | 50.00 | 60.00 | 1:1 | New Avg: 55.00 (Cost basis increases) |
| High Fee Impact | 10.00 | 9.00 | 1:1 | Fees may push Break-even above 10.00 |
| Penny Stocks | 0.05 | 0.03 | 1:5 | Volume heavily weights the new lower price |