# Unit of Measure (UOM)


A unit of measure (UOM) defines how a product is counted and sold, such as each, case, pallet, pound, or gallon. Orders, catalogs, and inventory must agree on UOM or quantities go wrong. A buyer ordering cases while the supplier reads eaches is a classic source of over- and under-shipments.

## UOM hierarchy

Most distributed products have a hierarchy: eaches in a case, cases on a pallet. The same item carries a different GTIN at each level. An order specifies both the quantity and its unit of measure, and the conversions between levels have to be exact or the picked quantity will be wrong.

## UOM and order errors

A mismatch in unit of measure is one of the most expensive quiet errors in order entry, because the totals still look plausible. Validating each line's UOM against the item master catches a case-versus-each slip before it becomes a wrong shipment.

## Common UOM abbreviations

These are the abbreviations you will see on purchase orders, catalogs, and pick tickets. Two companies can use different abbreviations for the same unit, so check each trading partner's item setup.

| Abbreviation | Meaning | Typical use |
| --- | --- | --- |
| EA | Each | Single sellable unit |
| CS / CA | Case | Shipping carton of eaches; CA is the X12 code |
| BX | Box | Inner or retail box |
| PK | Pack | Multipack or inner pack |
| DZ | Dozen | 12 units |
| PL / PLT | Pallet | Full pallet quantity |
| CT | Carton | Carton, often used like case |
| BG | Bag | Bagged goods |
| RL | Roll | Film, tape, labels |
| PR | Pair | Gloves, footwear |
| ST | Set | Kits sold together |
| LB | Pound | Catch-weight and bulk items |
| KG | Kilogram | Metric weight |
| OZ | Ounce | Small weights |
| GA / GAL | Gallon | Liquids; GA is the X12 code |
| FT | Foot | Cable, pipe, lumber |

## UOM codes in EDI

In X12 the unit of measure travels in data element 355, the Unit or Basis for Measurement Code. On an EDI 850 purchase order it sits in PO103, right after the quantity in PO102. X12 uses CA for case while many ERPs store CS, so the map has to translate one to the other. A missed translation either rejects the line or, worse, loads it with the wrong unit.

## UOM conversion example

An item ships 12 eaches to a case and 60 cases to a pallet. An order for 2 pallets is 120 cases, which is 1,440 eaches. If a buyer sends a quantity of 120 with UOM EA and the ERP assumes CS, the warehouse picks 1,440 units instead of 120. The order total still looks like a normal number, which is why this error gets past manual review.

| Level | Contains | Quantity for 2 pallets |
| --- | --- | --- |
| Pallet (PL) | 60 cases | 2 |
| Case (CS) | 12 eaches | 120 |
| Each (EA) | 1 unit | 1,440 |

## FAQ

### What does UOM stand for?

UOM stands for Unit of Measure, the way a product is counted and sold, such as each, case, pallet, pound, or gallon.

### What is a UOM conversion?

A UOM conversion translates a quantity from one unit to another, such as eaches to cases, using the item's pack hierarchy. Getting it wrong causes over- or under-shipments.

### What does EA mean on a purchase order?

EA means each, a single sellable unit. A line for 24 EA is 24 individual units, not 24 cases.

### What is the difference between CS and CA?

Both mean case. CA is the X12 EDI code for case, while many ERPs and catalogs use CS. EDI maps translate between them.

## Sources

- [ASCM supply chain terminology](https://www.ascm.org)