Calculate your weighted average cost basis across multiple stock purchases. See per-lot P/L, position value, break-even price, and average-down scenario analysis.
When you buy a stock multiple times at different prices, knowing your weighted average cost basis is essential for making informed sell decisions and calculating taxes. This calculator takes all your purchase lots and computes the overall average cost, position profit/loss, and break-even price.
The per-lot analysis breaks down P/L for each individual purchase, revealing which entries are profitable and which are underwater. Color-coded bars give you instant visual feedback on your best and worst-timed buys. This is the same data your brokerage tracks, but presented in a cleaner analytical format.
The average-down simulator shows exactly how buying additional shares would lower (or raise) your average cost. Enter a potential buy price and shares, and the calculator maps out multiple scenarios showing how many shares you'd need to bring your average to specific levels. This is invaluable when deciding how much capital to commit to a position. Check the example with realistic values before reporting.
Track your average cost across multiple stock purchases instantly. See break-even prices, per-lot P/L, and simulate how additional purchases change your average — all essential for timing your next buy or sell. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Average Cost = Total Cost / Total Shares Total Cost = Σ(Price_i × Shares_i) Unrealized P/L = (Current Price − Avg Cost) × Total Shares Break-Even Price = Average Cost New Average = (Old Cost + New Purchase) / (Old Shares + New Shares)
Result: Average Cost: $153.33, 60 shares, +14.1% unrealized gain
Six DCA purchases at different prices average to $153.33/share. At $175, the 60-share position is worth $10,500 with $1,300 (14.1%) unrealized gain.
Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.
Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes
Use this for repeatability, keep assumptions explicit. ## Practical Notes
Track units and conversion paths before applying the result. ## Practical Notes
Use this note as a quick practical validation checkpoint. ## Practical Notes
Keep this guidance aligned to expected inputs. ## Practical Notes
Use as a sanity check against edge-case outputs. ## Practical Notes
Capture likely mistakes before publishing this value. ## Practical Notes
Document expected ranges when sharing results.
The weighted average price of all your shares. Total dollars invested divided by total shares owned. Used for tax calculations and P/L tracking.
Only if you still believe in the investment thesis. Averaging down on a declining stock with broken fundamentals just increases losses. Average down on temporary dips, not broken companies.
Your total cost stays the same, but shares double (for 2:1 split). So average cost per share halves. Total position value is unchanged.
When you sell, your capital gain is (Sell Price − Average Cost) × Shares. Lower average cost = higher taxable gain. You can also use specific lot identification for tax optimization.
FIFO sells your oldest shares first. Average cost uses the weighted average. For stocks (not mutual funds), specific lot identification is usually optimal for tax purposes.
Both. Overall average gives your break-even. Per-lot tracking enables tax-loss harvesting — selling underwater lots to offset gains elsewhere.