Stocks & Investing · Introduction
DCA / Dilution Calculator
Estimate how many shares at the current price would reach your target average.
Updated 2026-10-25 · ThinkVault Tools
What can this tool help you do?
Estimate how many shares at the current price would reach your target average.
Check the purpose and assumptions, then open the tool. Return to the guide for details.
How is stock averaging down (DCA) calculated?
How is stock averaging down (DCA) calculated?
Averaging down lowers your average cost per share by purchasing additional shares at a lower market price. The basic formula is New Average Cost = (Existing Cost Basis + New Capital Added) ÷ (Existing Shares + New Shares Bought). This tool works in reverse to find the exact share count and capital needed to reach a target average price.
Example: averaging 100 shares from $100 down to $75
Suppose you hold 100 shares at an average cost of $100 ($10,000 invested) and the stock trades at $60. To bring your average cost down to $75, you need to buy 167 shares at $60 (adding $10,020), bringing your total position to 267 shares at an average cost of about $75.
Method
Target-average formula: Shares to buy = Existing shares × (Current average − Target average) ÷ (Target average − Current price), rounded up to whole shares. Board lots vary by security; verify the actual lot. 1 means whole shares; no ticker-based guess is made.