Selling by the box, the piece and the foot: units of measure explained

Units of measure are where general retail POS systems and hardware stores part ways. A café sells a latte. A hardware counter sells a box of 200 screws, or 12 of them; a 50 m coil of wire, or 7 m of it; a sheet of plywood, or a pack of ten. If the POS can’t do that from one item, the store creates workarounds, and the workarounds wreck the stock count.

The problem with “one SKU per pack size”

The common workaround is to create two items: Wood screw 3.5×40 – box and Wood screw 3.5×40 – single. It looks fine until:

• someone opens a box to sell singles, and nothing tells the system that one box became 200 singles;
• the box count goes negative while singles show 400 that don’t exist;
• reorder alerts fire on one SKU while the other is overstocked.

Every count then needs a manual “box breaking” adjustment, and nobody does them on a Saturday.

How base units and sub-units work

A base unit is what stock is kept in. A sub-unit (or pack unit) is defined as a multiple of it.

Item	Base unit	Sub-units
Wood screw 3.5×40	piece	Box 200 (= 200 pieces), Carton (= 2,000 pieces)
Copper wire 2.5 mm²	metre	Coil 50 m, Drum 100 m
Hex bolt M10×60	piece	Box 50
Plywood 18 mm	sheet	Pack 10

When the cashier sells 2 × Box 200, stock drops by 400 pieces. When they sell 12 pieces, it drops by 12. One count, always right. In Hardware Store POS you switch sub-units on in settings, create units as multiples of others, and choose per item which units it can be sold in. See units of measure and the set-up guide.

Choosing the base unit

Pick the smallest unit you ever sell. If you sometimes sell single screws, the base is the piece, even though 95% of sales are boxes. If you never break a box, the box can be the base.

For lengths, decide between feet and metres by what customers ask for. US stores sell in feet; UAE and Pakistan stores mostly sell in metres, except pipe and wire, which are often sold by the foot in Pakistan. Allow decimals where customers buy part lengths (2.5 m).

Price every unit deliberately

The box usually costs less per piece than singles; that’s the reason people buy the box. So set a selling price on each unit, rather than letting the till divide or multiply:

• Single screw: 0.08
• Box of 200: 12.50 (0.0625 each)
• Carton of 2,000: 115.00

The test rig on the units page shows the saving a customer sees.

Buying in one unit, selling in another

Suppliers sell cartons and coils; you sell pieces and metres. Receive purchases in the pack unit and stock converts to the base. Your costs per base unit stay right, which keeps margin reports honest.

Labels and barcodes per unit

Give the box its own barcode label so a scan picks the box; keep the manufacturer barcode on singles. Shelf labels can show both prices side by side so customers see the box saving.

Checklist before you go live

1. Create base units: piece, metre, foot, kg, sheet, bag.
2. Create packs as multiples: Box 50/100/200, Coil 50 m, Pack 10.
3. Import items with their base unit and allowed sub-units.
4. Price every unit.
5. Count one fastener family in boxes and pieces to prove the multipliers.

Related: How to import 30,000 SKUs into a new POS · Bin locations