Start with net revenue
Use the revenue actually attributable to the order after discounts and adjustments.
Subtract product cost
COGS should reflect the cost of the specific SKU or items sold.
Add operational costs
Shipping, gateway fees, marketplace fees and fulfillment cost reduce contribution.
Account for returns
Return shipping, refunds and inventory disposition can materially change the result.
Include acquisition cost when available
Advertising or campaign cost can show whether profitable fulfillment still results in profitable growth.
Choose a contribution-profit definition
Decide which direct costs belong to the order-level calculation and use the same definition consistently. This makes product, channel and campaign comparisons meaningful.
Use profit as an operational signal
Low contribution can point to discounting, expensive delivery areas, high-return SKUs, payment fees or acquisition cost. Profitability becomes more valuable when managers can trace the reason.
Every event should remain connected to the product, contact or transaction that created it. That is what lets ERP explain a number instead of only displaying it.