How to set up units of measureكيفية إعداد وحدات القياس

You buy paint by the gallon and sell it by the millilitre. You buy screws by the box and sell them one at a time. You buy steel by the ton and sell it by the kilo.

Other systems make you open a separate item for each unit and then link them together. Libra puts every unit on the same item, so there is one item, one stock figure, and one cost - and you buy and sell in whatever unit suits.

The grid is on the item's Item definition tab. See The item definition screen for the rest of the screen.

1. Decide the basic unit: always the smallest

The basic unit is the one Libra counts in internally, and it must be the smallest unit you ever deal in. If you sell paint down to the millilitre then the basic unit is the millilitre, even if you have never once bought a millilitre of anything.

Get this wrong and you cannot express the small quantities later without fractions.

2. Add one row per unit

3. Fill in the formula

Formula always answers the same question: how many basic units are in one of these?

With the millilitre as the basic unit:

The basic unit's own formula is always 1.

4. Give each unit its own code

Each row can carry its own Symbol and Barcode, and it is worth doing, because a litre and a gallon of the same paint are different things at the till.

A convention that works: take the item's code and suffix the unit.

The Symbol is the item's SKU - the code you find it by, alongside the name and the barcode. You may use a manufacturer's global code (a UPC or EAN printed on the part) or your own numbering. Leave it blank and Libra numbers it for you, if Automatic generation of symbol is switched on - see Item properties & categories.

For a part that legitimately has several codes - a global SKU, your own, and a barcode - use the Alternative barcode button on the ribbon. Be careful: run every item at that level of detail and you will eventually give two items the same code, and then neither scans reliably.

5. Name units so a human can act on them

Call it gallon 4L, not gallon - there are 5-litre and 10-litre gallons too. The name is what you say to the person in the store when you tell them what to fetch, so it has to be unambiguous on its own.

What this replaces

Without units you would buy a 4-litre gallon and then need a production operation just to break it into millilitres before you could sell any. With them, the same item is bought in gallons and sold in millilitres and Libra does the conversion. Reserve production for genuinely making or dismantling something.

Next steps

• The item definition screen
• How to create an item