Unit of Measure (UoM) in ERPNext
A Unit of Measure (UoM) defines how an item is measured, purchased, sold, manufactured, or stored. ERPNext comes with several predefined UoMs, and you can create additional ones based on your business requirements.
A Unit of Measure (UoM) represents the standard unit used to quantify an item. Every inventory transaction in ERPNext uses a UoM to determine the quantity being purchased, sold, transferred, or consumed.
Common examples include:
- Nos (Numbers)
- Kg (Kilograms)
- Gram
- Meter
- Box
- Pack
- Litre
A business may purchase Sugar in Kilograms, sell it in Packets, and store it in Kilograms. ERPNext handles these measurements using UoMs and conversion factors.
1. Creating a New UoM
ERPNext provides many standard Units of Measure by default. If your business requires additional units, you can create your own.
- Go to the UoM list.
- Click New.
- Enter the name of the Unit of Measure.
- Configure additional settings if required.
- Save the document.
2. Must be Whole Number
Each UoM includes a Must be Whole Number option.
When enabled, ERPNext allows only whole-number quantities for that unit. Decimal or fractional values cannot be entered.
Enable Must be Whole Number only for units that cannot be divided, such as Pieces, Boxes, or Bottles. Leave it disabled for units like Kilograms, Litres, or Meters where fractional quantities are common.
Example:
- Nos → 1, 2, 10 ✔
- Nos → 1.5 ✘
- Kg → 2.75 ✔
3. UoM Conversion Factor
Creating a UoM only stores its name. The relationship between different Units of Measure is maintained separately using the UoM Conversion Factor.
Conversion factors allow ERPNext to automatically convert quantities from one unit to another during transactions.
Example conversion factors:
- 1 Box = 10 Nos
- 1 Kg = 2.20462 Pounds
- 1 Carton = 24 Bottles
If you create a new UoM that will be converted into another unit during inventory transactions, you should also create the corresponding UoM Conversion Factor.
4. Why Conversion Factors are Important
Conversion factors ensure accurate inventory calculations across different business processes.
ERPNext automatically converts quantities whenever different UoMs are used in purchasing, selling, manufacturing, or stock movements.
- Maintains accurate stock balances.
- Ensures correct inventory valuation.
- Supports purchasing and selling in different units.
- Prevents manual quantity calculations.
5. Benefits of Using UoMs
- Standardizes how inventory is measured.
- Supports multiple selling and purchasing units.
- Improves inventory accuracy.
- Simplifies manufacturing and stock transactions.
- Enables automatic quantity conversions using conversion factors.
Summary
Units of Measure (UoMs) define how items are quantified in ERPNext. While the UoM document stores the measurement unit itself, quantity conversions are handled through UoM Conversion Factors. Together, they enable businesses to purchase, sell, manufacture, and manage inventory using multiple units while maintaining accurate stock records.
