Barcodes on goods sold by weight: how a weight code works

You weigh some cheese or meat, the scale prints a label, the cashier scans it and the total appears at once. The code on that label is not like the one on packaged goods: it hides not only the item but also the weight or price of that very portion. Once you know how it works, many till and stock-count errors make sense.

What is hidden inside the code

A carton of milk always carries the same code: one item, one number. With goods sold by weight every portion is different: 1.250 kg for one customer, 0.730 kg for the next. You cannot create a separate code for every possible weight. So the scale puts two things into the code: which item it is and how much.

A common layout uses the 13-digit EAN-13 format:

• a prefix at the start reserved for use inside one store, for example 21;
• the item code, five digits, for example 12345;
• the weight in grams, five digits, for example 01250;
• a check digit at the end.

Put together: 2112345012506. From the first digits the till software knows the item is sold by weight, finds the product card by 12345, reads 01250 as 1.250 kg and multiplies it by the price per kilogram. The scale and the till must agree on what each digit means. The layout varies between shops and programs: the item code may have four digits, and some systems store a ready-made amount instead of the weight.

Such a code only means something inside your own store. Do not pass it outside, to other outlets or a supplier, as an item code. Check the prefix range and the current rules with your GS1 member organisation or the software documentation.

Weight or price: what to encode

The main convenience of a weight code is that a price change does not force you to reprint labels; the till takes the current price per kilogram from the database. If the price is stored in the code, the amount is frozen on the label itself, and after a price change old labels give the wrong total. Choose the second kind only if your scale or till cannot do the first, and on the day the price changes pull the old labels from sale.

What belongs on the label

Next to the code, print the item name, weight, price per kilogram, total and packing date; for perishable goods add the expiry date. Stick the code on a flat part of the pack, where the film is not wrinkled and there is no fold. Adhesive grips poorly on a wet or greasy surface, so choose a dry, clean spot. Leave blank margins on both sides of the code, otherwise the scanner cannot find where it starts.

The weight of a tray or container (the tare) must be subtracted on the scale, or the customer pays for the packaging too. Check the tare at the start of the shift and whenever the tray changes.

Checking the scale and the till

When you add a new item or change a setting, run through this test:

1. Enter the item code on the scale, identical to the one in the database.
2. Weigh one portion and print the label.
3. Scan it at the till and look at the name, weight and total.
4. Recalculate the total by hand: 1.250 kg × 18,000 so'm = 22,500 so'm.
5. Repeat with a very small weight (0.050 kg) and a large one.

If the till cannot find the item, usually the code is missing from the database or was typed differently on the scale. If the total is off, the weight positions or the price unit (kilogram or gram) are set wrongly. Also find out the current requirements for verifying and sealing the scale itself.

Weighed goods during a stock count

In a count, scanning the label adds the weight of that portion, and the software sums every weight under one item code. The most common muddle is a half-sold pack that still carries the old label. The weight on it is no longer true, so weigh what is left and print a new label. Open goods with no label should be weighed and entered by hand.

Conclusion

A weight code has two parts: what and how much. When the layout is identical on the scale and the till, price errors fall. The Shtrix team checks your scale labels, scans them at the till and sets up how weighed goods are counted in a stock count.