Understanding Units of Measure (UOM) - Simple Guide

When working with product data, one thing that always comes up is Units of Measure, or UOM. At first, it can feel confusing, but once you get the basics, it becomes very straightforward. Let’s break it down in a simple way.

What is a UOM?

A Unit of Measure (UOM) is just a way to describe how we count or measure something.

For example:

• We count items as each
• We measure weight in grams or kilograms
• We track time in seconds or minutes

UOM Classes – Grouping Similar Units

UOMs are grouped into something called classes. Each class contains similar types of measurements.

Some common examples:

• Quantity → each, dozen, box
• Weight → gram, kilogram, pound
• Time → second, minute, hour
• Volume → cubic inches, cubic feet

Each class has one base unit. This is the main unit used for all calculations.

For example:

• Quantity → base is each
• Weight → base is usually gram
• Time → base is second

UOM Class, UOM and Base UOM - Examples

Unit of Measure Class	Units of Measure	Base Unit of Measure
Quantity	dozen box each	each
Weight	pound kilogram gram / ounce	gram / oz
Time	hour minute second	second
Volume	cubic feet cubic centimeters cubic inches	cubic inches

How Conversions Work

All conversions are tied to the base unit.

Let’s take a simple example from the Quantity class:

• 1 Box (8 items) = 8 Each
• 1 Box (4 items) = 4 Each

So everything is calculated using each behind the scenes.

What is Primary UOM?

The Primary UOM is the default and base unit in which an item is:

• Stored in inventory
• Tracked for quantity
• Valued (costing)
• Reported across the system

UOM Class, UOM and Base UOM – Conversion Factor

Unit of Measure Class	Unit of Measure	Base Unit of Measure	Conversion Factor
Quantity	dozen	each	12 (1 dozen = 12 each)
Weight	pound	gram	454 (1 pound = 454 grams)
Time	minute	second	60 (1 minute = 60 seconds)

What is Stocking UOM?

• A default stocking unit of measure lets you store the same item in different UOMs across or within organizations.
• Stocking UOMs can be set at the organization level, subinventory level, or both.

Item (Example): Mineral Water Bottle

Advanced UOM Conversion Types

IntraClass Conversion (Healthcare)

• Intra-class UOM conversion allows inventory to be converted between unit of measures within the same UOM class.
• Conversion Logic (Same UOM Class)
• 1 Target UOM = Conversion Factor x Primary UOM
• 1 Box = 4 Each

InterClass Conversion (Manufacturing)

• Inter-class UOM conversion allows inventory to be converted between unit of measures across the UOM class.
• The inventory tracking will always be done in terms on Primary UOM of an item.
• Volume to Weight (Liters to Kgs)
• 1 Target UOM (Target Class) = Conversion Factor × Primary UOM (Primary Class)
• 1 L = 0.92 KG

Packaging Strings - Items (Healthcare)

Base Unit of Measure	Conversion Multiplier	Units of Measure	Unit of Measure Class
Glove	1	Each	Quantity
Each	120	Box	Quantity
Box	24	Carton	Quantity
Carton	16	Case	Quantity

Multiplier	Content UOM	UOM Name	Base Unit Conversion
120 X	Each	= Box	120
24 X	Box	= Carton	2,880
16 X	Carton	= Case	46,080

Dual Measures (Manufacturing / Food & Beverage )

Dual Units – Two Ways to Track the Same Item

In some industries, especially manufacturing or food, items are handled using two units.

• Primary UOM → for tracking
• Secondary UOM → for pricing

Example:

• Tuna is tracked as each (per fish)
• But priced based on weight (pounds)

This helps businesses stay accurate in both inventory and billing.

Dual Measures – How it works?

• Use dual units of measure: manage items in the primary unit (Each) but price them in a secondary unit (Pounds).
• Example: Sushi Tuna is handled as one fish each, but priced based on its weight.
• Track both units throughout the order process since each fish varies in size and price.

UOM might look technical at first, but it’s really just about keeping things consistent.

Once you understand:

• classes
• base units
• and simple conversions

everything else falls into place.