Stock Average Calculator
Find your average cost per share across several buys, and how many shares it takes to average down or up
Your Purchases
Optional, for your gain or loss
Average cost per share
$43.75
200 shares for $8,750.00
Total shares
200
Total cost
$8,750.00
Market value
$8,400.00
at $42.00 a share
Unrealized loss
-$350.00
-4.00% of cost
Average Down (or Up) Planner
Buy 75 shares at $30.00 (about $2,250.00) to bring your average to $40.00.
Purchase prices vs your average
The dashed line is your average cost
Cost of each purchase
$8,750.00 in total
Your Purchases
| Purchase | Shares | Price | Cost | Share of Position |
|---|---|---|---|---|
| Buy 1 | 100 | $50.00 | $5,000.00 | 50.0% |
| Buy 2 | 50 | $40.00 | $2,000.00 | 25.0% |
| Buy 3 | 50 | $35.00 | $1,750.00 | 25.0% |
Average Cost Basis
Your average cost is the total you paid, fees included, divided by the shares you own. It's also your break-even price: above it the position is in profit. Buying more below your average lowers it (averaging down); buying above it raises it.
The Formulas
Average = total cost ÷ total shares
Shares needed = (target × shares − cost − fee) ÷ (buy price − target)
Each purchase's cost includes its fee.
Averaging Down Wisely
- •A lower average only helps if the stock recovers
- •Re-check why you own the stock before adding to a losing position
- •Keep one position from growing too large a share of your portfolio
- •Brokers report cost basis for taxes; check which lots they sell first
- •Dollar-cost averaging into a broad index fund spreads out timing risk