Weighing Scale & Selling by Weight

How it works in one paragraph

A barcode-printing scale doesn't send data down a wire — it prints a sticker. The clever part is that the barcode on that sticker isn't a normal product barcode: the scale hides which product it is and how much it weighed inside the digits. So when your cashier scans the sticker, YellowPOS pulls those two numbers back out. The label is the connection between the scale and the POS.

Here is a real example. Your scale prints 2000211352 plus a check digit:

• 2 — a fixed digit that means "this is a store-printed label, not a manufacturer's barcode"
• 00021 — the product's PLU code (feta cheese)
• 01352 — the weight in grams, so 1.352 kg

At $12.00 per kilo, the POS adds a line for 1.352 kg × $12.00 = $16.22 and takes 1.352 kg off your stock.

1. Mark the product as sold by weight

Open the product and set its Unit to a weight — kg, g, lb, and so on. That single choice changes how YellowPOS treats it: the price becomes the price per unit (per kilo, not per piece), the quantity can be a decimal, and the stock level is a weight. Enter your stock the same way — 10 means 10 kg, not 10 packets.

Open Products

2. Give the product its PLU

On your scale, every item has a short PLU code — a number like 21 that you press to select feta cheese before weighing. YellowPOS needs to know that 21 means feta cheese, so add that number to the product's barcodes, using the same barcodes section you already use for normal products.

Leading zeros don't matter. If your scale pads the code to 00021 but you typed 21, YellowPOS still matches them.

3. Tell YellowPOS your scale's barcode format

Every scale brand lays out its digits slightly differently, so you describe your scale's layout once in Settings → Weighing scale. You do this with a mask — a short pattern that spells out what each digit position means:

• A plain digit (like 2) must match exactly. This is the flag that tells YellowPOS "this is a scale label."
• I — a digit belonging to the item's PLU code
• V — a digit belonging to the value (the weight or the price)
• C or X — ignore this digit (usually the check digit)

So the most common format in the region, 2IIIIIVVVVVC, reads as: a literal 2, then 5 digits of PLU, then 5 digits of value, then a check digit to ignore.

Two more settings finish the picture:

• What the value means — most scales encode the weight; some encode the total price instead. Both are supported.
• Divisor — how to turn those digits into a real number. If your scale writes the weight in grams and you sell per kilo, the divisor is 1000 (so 01352 → 1.352 kg). If it writes a price in cents, use 100.

Open Settings

4. Check it with the built-in tester

You don't have to guess whether you got the format right. Under the settings there's a tester: weigh something, take the label your scale actually printed, and type its digits in. YellowPOS shows you exactly what it read — the PLU it found, the product name it resolved, and the weight or price it calculated. If the product name that comes back is the right one and the weight matches what the scale display said, you're configured correctly.

The tester runs on whatever is currently in the form, so you can adjust the mask and try again immediately without saving. If a label doesn't parse, the tester tells you why — usually the mask is a different length than the barcode.

5. Sell

That's the whole setup. From now on your cashier's job is unchanged: weigh, stick the label on the item, scan it at the POS. The line appears with the weight and the correct price. Scan a second piece of the same cheese and the weights add up on the same line.

Normal barcodes are completely unaffected — YellowPOS always tries a regular product match first, and only reads a barcode as a scale label if it doesn't match a real product.

No scale? You can still sell by weight

The scale is optional. Once a product has a weight unit, two things happen on the POS even with no scale in the building:

• Tap the product on the grid and YellowPOS asks you to type the weight instead of silently adding "1".
• Edit the quantity directly on the order line — type 1.35 and the total re-prices instantly.

This is also your fallback if the scale's printer runs out of labels mid-shift.

Stock, receipts, and returns

Everything downstream understands weights. Stock drops by the exact amount sold (10 kg minus 1.352 kg leaves 8.648 kg). The receipt prints 1.352 kg × $12.00 rather than a meaningless "× 1". And if you void or return the order, the exact weight goes back into stock — no drift, no rounding creep after a hundred sales.

It works offline

Scanning a scale label is handled entirely on the device, exactly like a normal barcode. If your internet drops mid-shift, you keep weighing and selling; the orders queue up locally and sync when you're back online. The only part that needs a connection is the settings screen where you configure the format — and that's a one-time job.

This feature is in beta

Scale support is new and there are a lot of scale models out there. If your labels don't parse, don't fight the mask on your own — send us a photo of the printed label and the barcode digits and we'll tell you the exact settings for your model. That feedback is what makes it work for the next shop.

Frequently asked questions