If you don't know your exact Adjusted Cost Basis (ACB), you aren't trading—you are guessing. The ACB is the single most important metric in the option wheel strategy. It tells you exactly where your true break-even translates on the chart.
This guide provides the definitive formulas for calculating your ACB, so you can build your own option wheel strategy calculator (or just use ours).
The Master ACB Formula
Your Adjusted Cost Basis is simply what you paid for the shares, subtracted by all the money the market paid you during the process.
ACB per Share = (Total assignment purchase price − Total net option premiums collected) ÷ 100 shares
Example Calculation Walkthrough
Let's map out a multi-trade campaign on a single contract of a completely fictional stock, XYZ.
- Trade 1: Sell a $100 put. Collect $1.50 in premium. (Net cash: +$150)
- Trade 2: The put expires. Sell a $105 put. Collect $2.00 in premium. (Net cash: +$200)
- Assignment: XYZ crashes to $102. You are assigned at $105. You buy the shares for $10,500.
Let's calculate the ACB right now:
- Total paid: $10,500
- Total premium collected: $150 + $200 = $350
- True cost: $10,500 - $350 = $10,150
- ACB per Share: $101.50
Even though you were assigned at $105, and the stock is at $102, you are actually sitting on a $50 unrealized profit because your true break-even is $101.50.
Adding Rolls to the Calculator
Rolling is where spreadsheets die. If you roll an option, you must subtract the Buy-to-Close debit and add the Sell-to-Open credit to your premium tracking. If you roll for a net credit of $0.50, you add $50 to your total premium collected. If you pay a net debit of -$0.20, you subtract $20.
The Better Way: Automated ACB Tracking
Building a spreadsheet calculator that flawlessly handles multiple rolls, partial assignments, and dozens of covered call cycles requires a master's degree in Excel logic. One typo in a cell ruins your entire portfolio's math.
You don't need to build a calculator. We already built the perfect one. OptionWheelTracker automatically calculates your ACB, updates your break-evens instantly after every trade, and handles complex rolling logic with zero manual data entry. Start tracking for free.