Case and pack pricing: turning supplier case costs into Shopify unit costs
Short version: If a supplier sells by the case and you sell single units, multiply the case quantity by units per case for stock, and divide the case price by units per case for Cost per item. "5 cases of 24 at 7.20" is 120 units at 0.30. Most receiving mistakes come from doing only one of the two.
Wholesale suppliers price in cases, packs, inners, outers, dozens and kilos. Shopify tracks stock and cost per variant, in whatever unit that variant is sold. Getting from one to the other is simple arithmetic, but it's easy to slip, and the mistakes are expensive: a cost 24 times too high wipes a product out of your profit reports, and stock 24 times too low means it shows as sold out.
The two conversions
For each invoice line, find the units per case (sometimes called pack size, case quantity or inner quantity). Then:
- Stock to receive = cases received × units per case
- Cost per item = case price ÷ units per case
| Invoice line | Units per case | Receive | Cost per item |
|---|---|---|---|
| 5 × Dark chocolate 70% CS/24 @ 7.20 | 24 | 120 | 0.30 |
| 2 × Oat drink 1 L 6-pack @ 8.40 | 6 | 12 | 1.40 |
| 3 × Filter papers (box of 10 packs) @ 19.00 | 10 | 30 | 1.90 |
| 1 dozen mugs @ 50.40 | 12 | 12 | 4.20 |
Check the line total either way: 5 × 7.20 = 36.00 is the same money as 120 × 0.30. If your converted quantity × unit cost doesn't equal the invoice line total, something is off.
How to spot pack pricing on an invoice
- Abbreviations: CS, CTN, CT (carton), BX, PK, DZ, OUT/INN (outer/inner), VE (German Verpackungseinheit), colis (French), caja (Spanish).
- Formats like 24 × 100 g, 6/1 L, 12x, x24 in the description.
- A separate "pack" or "unit" column. Some invoices show both the unit price and the case price; make sure you use the right one.
- A unit price that's suspiciously high compared with your current cost, often a round multiple of 6, 10, 12 or 24.
Watch out for these cases
The quantity is already in units
Some suppliers write "120 × chocolate, case of 24, @ 0.30". The case size is just information; the quantity and price are already per unit. Multiplying again would give 2,880 units. Always check with the line total.
Mixed lines on one invoice
The same invoice can price one product per case and another per unit. Treat every line separately.
Weight-based pricing
Coffee at 18.00 per kg, sold in 250 g bags: cost per bag is 18.00 × 0.25 = 4.50 (plus the bag and label if you pack it yourself).
Selling both singles and cases
If you sell a case and a single as separate variants, Shopify tracks stock separately for each. Decide which variant you receive into. Many shops receive everything as singles and sell the case through a bundle app, so stock stays in one place.
Free units
"Buy 10 get 1 free" lines change your unit cost: 10 × 12.00 for 11 units is 10.91 each. Receive 11, cost 10.91.
Recording pack sizes so you only work them out once
Keep a simple sheet per supplier with their code, your SKU, and units per case. Some shops put the pack size in a product metafield or in the supplier SKU field of native purchase orders. Whatever you choose, keep it in one place and update it when the supplier changes their packaging.
Doing the conversion in a spreadsheet
- Paste the invoice lines with columns: code, description, quantity, price, line total.
- Look up units per case from your mapping sheet with
XLOOKUP. - Add Units received = quantity × units per case, and Unit cost = price ÷ units per case.
- Add a check column: units received × unit cost − line total. It should be zero (or within a cent of rounding).
- Use the results for receiving and cost updates (see receiving inventory and bulk cost updates).
Where Box to Shelf helps
Box to Shelf reads pack sizes from the invoice line ("CS/24", "6 × 1 L", "case of 12" and similar) and compares the supplier's price with your current cost to decide whether the line is priced per case or per unit. When it converts, the review screen shows it, so "5 cases of 24 at 7.20" appears as +120 units at 0.30. When the pack size is ambiguous it's flagged for you to confirm rather than guessed. The line total check runs after conversion, so a wrong conversion shows up before you apply.
Questions
How do I calculate unit cost from a case price?
Divide the case price by the units per case. A case of 24 at 7.20 is 0.30 per unit.
Should I sell cases and singles as separate variants?
If you sell both, yes, but Shopify tracks stock per variant, so you'll need to decide which variant holds the stock and move it when you split cases.
Sources
- Shopify Help Center: Cost per item
- Shopify Help Center: Inventory CSV (whole-number quantities)
- Shopify Help Center: Creating purchase orders (supplier SKU)
Shopify changes its admin often. Steps were checked against the Shopify Help Center in November 2026; if a menu has moved, the help center links above have the current version.