ZN ERP
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Units of Measure

Common UOMs in ZN ERP, conversion rules, and how to set up a new one.

5 min read Updated Jun 2026   Reference

Units of Measure (UOM)

Every item in ZN ERP has a base UOM — the smallest sellable / stockable unit. Items can also have one or more alternate UOMs for buying, selling or stock-taking, each with a conversion factor back to the base.

For example, a medicine's base UOM might be Tab, with alternate UOMs Strip = 10 Tab and Box = 100 Tab. The system always stores quantity internally in the base UOM and converts on display.

Common UOMs (built-in)

UOMFull nameTypical use
Each / Nos Each / Numbers Loose items counted by piece.
Box Box Cartons of finished goods.
Pkt / Pack Packet Pre-packaged items (chips, biscuits).
Strip Strip Pharmacy — 10 tablets per strip is typical.
Tab Tablet Pharmacy base UOM for solid orals.
Cap Capsule Pharmacy base UOM.
Bot / Bottle Bottle Liquids sold in bottles.
Ml Millilitre Liquids sold by volume.
Ltr Litre Bulk liquids.
Gm Gram Small-weight items.
Kg Kilogram Bulk weight.
Mtr Metre Cables, fabric, pipes.
Cm Centimetre Small length goods.
Sqft / Sqmtr Square foot / metre Tiles, sheets, flooring.
Set Set Grouped items sold as a set (cutlery, tools).
Pair Pair Footwear, gloves.
Doz Dozen 12 of something (eggs, fruit).
Hr Hour Services billed by time.

Conversion rules

  • The conversion factor is always expressed as X alternate UOM = Y base UOM — e.g. 1 Strip = 10 Tab if the base is Tab.
  • Conversions are stored on the item, so two different medicines can both use Strip with different strip sizes (10 vs 15 tabs).
  • For weights / volumes the conversion is fixed (1 Kg = 1000 Gm) — it does not need to be defined per item, but you can still over-ride it.
  • Reports display the UOM that was used at entry time, but always recompute totals from the base. Stock reports default to base UOM unless overridden.
  • Tax rates apply per item, not per UOM — selling in Box vs Strip does not change the tax structure.

Setting up a new UOM

  1. Open Administration › Item Setup › UOM Master.
  2. Click Add. Enter the short code (3–5 letters), full name and category (Quantity / Weight / Volume / Length / Area / Time).
  3. If it is a weight/volume/length UOM, enter the conversion to the SI base in that category.
  4. Save. The UOM is now selectable on any item.
  5. To use it on an item, open the item, go to the UOMs tab and add a row: UOM, Conversion to base.

Common gotchas

  • Two strip sizes for the same medicine — do not use one alias. Set up the item once with base Tab and pack the strip count into the item-level conversion.
  • Decimal quantity in base UOM — if you buy in Kg but sell in Gm, enable Allow decimals in base UOM for that item.
  • Changing base UOM — only possible when stock is zero. The system will refuse otherwise to avoid quantity corruption.
  • Negative stock with mixed UOMs — usually caused by a sale entered in the wrong UOM (e.g. selling 10 Strip when you meant 10 Tab). Always glance at the UOM column on the invoice grid.
Warning — never re-purpose an existing UOM code for a different unit. Box meaning 10 each on item A and 100 each on item B is normal; Box meaning "a sample" on item C is a recipe for chaos in reports.