How to use it
- Enter the shares and the price for each purchase. Leave unused purchases at 0.
- In Average cost mode, read the average, the total shares and the total spent.
- In Shares for a target mode, also enter the current price and the average you want.
How it works
- Average = total spent ÷ total shares.
- Shares to buy x = shares × (average − target) ÷ (target − current price).
- After buying, (total spent + x × current price) ÷ (shares + x) equals the target.
Worked example
10 shares at 100 and 10 shares at 80 cost 1,800 for 20 shares: an average of 90. To bring 20 shares held at 90 down to 80 by buying at 70, you need 20 more shares, costing 1,400. The new total is 3,200 for 40 shares, which is 80.
Tips
- Averaging down adds money to a falling position, so only do it if you would buy at that price anyway.
- This is a calculation aid, not investment advice.