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Opex is your operating overhead for the selected date range: salaries, rent, software, and any other cost you categorize as Opex in Cost settings. It is subtracted from CM3, along with agency fees and other costs, to get CM4.

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Formula

Opex = Order fees (Opex) + Recurring expenses (Opex, prorated) + Variable costs (Opex, % of ad spend)

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Formula Components

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How It Works

Opex and Marketing are the only cost categories that can come from all three cost types:
  1. Order fees are calculated per order and move with order volume.
  2. Recurring expenses are converted to a daily rate (Monthly ÷ 30, Quarterly ÷ 91, Yearly ÷ 365) and multiplied by the days in your range that fall inside the expense’s effective dates.
  3. Variable costs take a percentage of ad spend for the range. If the cost’s effective dates cover only part of the range, Upstack scales it by the share of days covered.
Recurring and variable Opex are added when the report runs, not stored on orders, so edits show up right away. NC Opex and RC Opex split them by net revenue, so together they add up to Opex. See how the split works.

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Example

April (30 days). The store has 2,400 orders and $80,000 in ad spend. Divided by orders, that’s about $4.82 of overhead per order.

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How to Interpret It

Most Opex is fixed, so it doesn’t scale with sales. When revenue grows and Opex stays flat, the gap between CM3 and CM4 shrinks as a share of revenue. That’s operating leverage. If Opex rises in step with revenue, check whether the variable or order-fee parts are driving it. Comparing Opex to CM3 tells you how many months of contribution it takes to cover overhead. A month where CM3 is below Opex is a month the business lost money, even if ad campaigns looked profitable.

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Common Pitfalls

  • CM4 % and CM4 per Order ignore recurring and variable Opex. They’re computed from order-level costs and ad spend, so only Opex order fees reach them. The dollar CM4 includes everything.
  • Short ranges carry a slice of overhead. A one-day view shows one day of each recurring expense, which can make a slow day look deeply negative at CM4.
  • Changing the category moves the cost between tiers. A Marketing variable cost reduces CM3. The same cost tagged Opex reduces CM4 instead.

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FAQ

Both reduce CM4. Use Opex for recurring operating costs you want to track as overhead (payroll, rent, tools) and Other for anything that fits no category. Keeping them separate lets you chart Opex on its own.
Not in CM1 to CM3. Opex is subtracted only at CM4 (Operating Profit), so CM3 stays a clean view of order and marketing economics.
See all Contribution Margin metrics →