Cost of goods is the input Shopshot needs to turn revenue into profit. Shopify knows what you sold and for how much. It does not know what each item cost you. The COGS tab in Costs Setup is where you tell it.

Set a cost for each product or SKU. Shopshot uses these costs to calculate margin on the Products page, in Orders, and in the Profit & Loss statement.

When an order comes in, Shopshot records the product cost that is true at that moment and attaches it to the order permanently. If you update a cost later, past orders keep the cost that applied when they happened, so historical margins do not silently change. Only future orders pick up the new cost.

Most apps assume one cost per SKU forever. Shopshot supports the way costs actually move, across time and across order size, and it links to your shipping setup so product-level shipping can feed the shipping waterfall. See the Shipping Costs article.

Any SKU without a cost has incomplete margin. Shopshot flags missing costs so you can see exactly what is left to enter. Until costs are complete, treat store-wide margin as partial.

I updated a cost. Why did last month's profit not change? Because costs are snapshotted at order time, so closed periods stay stable.

What happens to margin if I never enter a cost? That SKU's margin stays incomplete and is flagged, rather than being assumed as zero-cost or fully costed.