How to track Shopify SKU costs when supplier prices change

Start with one supplier invoice and one Shopify order

Pull an invoice for a product with two variants. Match each supplier line to the variant on a real Shopify order. A product title such as ‘Cable organiser’ can describe both sizes of a pack, while each pack can have a different cost and shipping weight. A costing record should include the Shopify variant, your Shopify SKU, the supplier SKU, the invoice currency, and the unit you sell.

If a customer buys a two-pack and your supplier invoices by the piece, convert the invoice price to the cost of the two-pack before assigning it to that variant. Give different variants distinct SKUs. If a supplier renames a code, retain the old mapping for historical orders. See Shopify’s guide to variant SKUs.

Record the date each new cost takes effect

Keep one cost record per variant and effective date. Use the date the supplier began charging the new amount, with a note identifying the relevant order or invoice. If two suppliers fulfil the same SKU on the same day at different prices, keep the actual supplier invoice against the affected orders. A single default cost on that date can only estimate their combined cost.

In Shopify, add Cost per item under the product’s pricing settings and fill it in for each variant. Shopify records this cost on an order when it is created. Updating the current product cost leaves earlier order values in place. Shopify’s profit reports include variants that had a cost recorded at sale. Keep dated invoice records to investigate missing or disputed historical amounts. See Shopify’s cost-per-item documentation and the Shopify profit report definitions.

What happens when a two-pack costs 90 cents more?

Consider an Australian store that sells a two-pack. Its supplier charges A$8.40 per pack through 14 October and A$9.30 from 15 October. This illustrative reconciliation uses the units sold during each cost period.

Applying the latest cost to all 65 packs gives A$604.50. That would make October’s product costs A$22.50 too high. The error becomes harder to spot when a report covers multiple variants, price changes, and suppliers.

Handle shipping, bundles, and returns consistently

• Supplier bills. If the invoice has separate product and parcel charges, track the product as unit cost and the parcel under fulfilment. When a supplier quotes one delivered price, document which charges it includes before adding a shipping line elsewhere.
• Bundles. Record the actual bundle purchase cost or add up its underlying components, depending on how your supplier bills it. Give packs with different contents their own mappings.
• Returns. Record the cost recovery when your supplier credits the unit or it returns to sellable inventory, using the treatment agreed with your bookkeeper. A refund to the shopper and a credit from your supplier are separate events.
• Currency. If you buy in one currency and report in AUD or USD, retain the source amount and record the converted value from the supplier invoice or your documented conversion method.

Check cost coverage before you trust the margin

1. Take a completed reporting week and list the variants that sold, including new bundles.
2. For each variant, check that a supplier cost applies to the order date and that the quantity is measured in the same unit as the cost.
3. Compare three high-volume order lines with their supplier invoices. Pick at least one line before and one after a cost change.
4. Mark unknown costs as missing and enter zero only where the item genuinely carried zero cost. An explicit missing-cost list makes a margin report easier to verify.

Use the Profit Inspector sample dashboard to see how product costs, delivery charges, and payment fees appear in a profit breakdown. Bring your variant mappings and supplier invoices to the workspace setup guide when you are ready to review your own store.

Common questions