Unit conversion is a rule that tells the software how many of one unit are in another, such as 1 Carton = 24 Piece. With it you buy in cartons, bags or tons and sell in pieces or kilograms, and the stock stays in one count.
What is a stock unit (base unit)?
The stock unit is the one unit in which a product's stock is counted. Every product has exactly one. Choose the smallest unit you ever sell in: pieces for bulbs, kilograms for nails, meters for cable.
What is a conversion factor?
A conversion factor is the number of stock units in one of the other unit. In "1 Carton = 24 Piece" the factor is 24.
| Rule | Factor | Typical trade |
|---|---|---|
| 1 Dozen = 12 Piece | 12 | Garments, hardware |
| 1 Carton = 24 Piece | 24 | FMCG, beverages |
| 1 Coil = 90 Meter | 90 | Electrical cable |
| 1 Ton = 1,000 Kilogram | 1,000 | Steel, building material |
| 1 Than = 40 Meter | 40 | Cloth |
| 1 Bale = 25 Kilogram | 25 | Yarn |
How does a sale in another unit change stock?
The quantity is multiplied by the factor. Selling 10 cartons at 24 pieces each takes 240 pieces out of stock. The invoice keeps both figures: 10 Carton billed, 240 Piece moved.
The rate follows the unit. If a piece sells for Rs 50, a carton of 24 is Rs 1,200, until you type your own carton rate.
What if the pack size differs by product?
Then the rule must belong to the product. One brand packs 24 to a carton and another packs 48; one yarn count makes a 25 kg bale and another a 50 kg bale. A product-specific rule overrides the general rule for that product only.
Why must the software never assume a conversion?
Because a wrong assumption silently ruins the stock count. If no rule exists between the unit on the invoice and the product's stock unit, the correct behaviour is to stop and ask for the rule, not to guess.
What happens to old invoices when a pack size changes?
Nothing should happen. An invoice must keep the factor it was saved with. A carton that held 24 pieces last year and holds 20 this year was still 24 on last year's bills.
How do you choose units for your business?
- List the units you buy in and the units you sell in.
- For each product, pick the smallest as its stock unit.
- Add one rule for each other unit; make it product-specific where pack sizes differ.
- Check one invoice in each unit against the stock ledger.
In M-Tech Logistics: each type of business starts with its own units, and you add conversions under Products, Units & Conversion. General rules, product-specific rules, the inverse direction and the saved factor on each invoice all work as described here. See units in the software, then read about stock management.