An internal barcode for items without one: numbering and duplicates

Produce from the market, unpackaged goods from a small local maker, items you repack yourself, spare parts: many of them carry no barcode. Without one, you search for the item by name at the till and write it down by hand at a count, which is slow and error-prone. An internal code solves this, but only if it is built properly. A badly built code causes more confusion in a year than the old names did.

Which items need an internal code

An internal code makes sense when:

• the item has no factory code at all (handmade, a local maker, from a market);
• you repack the goods yourself, for example from a 25 kg sack into 1 kg bags;
• spare parts, raw materials and internal supplies;
• a bundle, such as a gift set of three items;
• a supplier has used one code for two different items.

If an item has a genuine factory code, do not invent another: use the one it has. Two codes on an item confuse a scanner.

Choosing the code type

There are normally two routes for an internal code. The first is Code 128: it takes letters and digits, is compact and every scanner reads it. For example, IK000123, where IK shows the code is internal. The second is an internal number in EAN-13 form: some till programs expect exactly that, but it risks colliding with the codes of real products. If your software accepts a code with letters, take the first route: a letter prefix sets your code apart from a factory code at once.

Numbering rules

A good system is simple:

1. The code should be a running number: 000001, 000002 and so on. Put no meaning into it.
2. Do not write the name, group or size into the code; keep them in the database. They change, while a stuck label does not.
3. One variant, one code: each size, colour and pack gets its own.
4. Never change or reuse an issued code. Even if the item is discontinued, the number stays vacant.
5. Fix the length in advance. Six digits reach 999,999, which for most businesses is practically endless.

A sizing example: 120 item types with 3 pack sizes each need 120 × 3 = 360 codes. They run from 000001 to 000360, and the rest stay in reserve.

Duplicates and collisions

An internal code carries three risks.

The first: one code issued to two items. It usually happens when a list is copied. Check for duplicates in Excel with a counting formula after every new row.

The second: one item entered twice and given two codes. Before issuing a new code, search for the item by name and its main attribute. Once a week sort the list by name and look at similar names: two codes most often originate there.

The third: an internal code matching the code of a genuine product. This only happens with a numeric EAN-style code, which is why a letter prefix is better.

Give the right to issue codes to one responsible person. If everyone keeps their own list, duplicates multiply. If a factory code later appears on the item, do not delete the internal one: many accounting systems keep several barcodes on one product card, so both will read. Check this in your own system.

The list and printing

Set up these columns in Excel: code, name, variant, pack, who issued it and when. Generate the running numbers with a formula, not by hand. Keep the columns in text format, otherwise leading zeros vanish. The label should carry the code, the item name and a human-readable number. First print five test labels, scan them and check that the card opens. Only then print the whole list. Stick the label on a flat part of the pack and do not cover factory text such as ingredients or the expiry date. On repacked goods, print the packing date on the label too.

Conclusion

An internal barcode works well when it is plain, sequential and meaningless. You need a separate code for each variant, a check for duplicates and one person in charge. The Shtrix team sets up the structure of internal codes for your uncoded goods, prints and applies the labels, and prepares the list in a form your accounting system can use.