Imagine your store sells cheese, meat, or nuts. A customer wants 0.75 kg of Parmesan, adds it to the cart, but the system saves 1 item. No 750 g, no correct delivery calculation. Overpayment can exceed $140–200 per month for a medium-sized store. The cart is not adapted for decimal quantities—this is not a Bitrix defect but a configuration feature. We configure goods by weight so that every detail is accounted for: from fractional quantities in the cart to PLU barcodes and stock sync with 1C. Our experience—over 10 years of Bitrix integrations, hundreds of projects—ensures you get a working solution. Contact us for a catalog audit.
How to Set Up Products Sold by Weight for Fractional Quantity?
Bitrix supports decimal quantities via the MEASURE field in b_catalog_product and the STEP parameter in the cart component. But by default, the quantity field validates only integers. Below are key settings.
Key fields of b_catalog_product for goods by weight:
-
MEASURE—ID of the unit of measurement fromb_catalog_measure(kg, g, l, etc.) -
QUANTITY_TRACE—track stock or not (Y/N) -
CAN_BUY_ZERO—sell at zero stock
Units of measurement use OKEI codes. Enabling fractional quantity for a product:
\Bitrix\Catalog\ProductTable::update($productId, [ 'MEASURE' => 6, // ID of measure "kg" from b_catalog_measure 'STEP' => '0.1', // quantity change step ]); Cart Component and Quantity Step
The bitrix:catalog.element component accepts the PRODUCT_QUANTITY_STEP parameter. For goods by weight, the step is set in the product's measure units. If a product is sold in 100-gram increments and the measure is kilograms, the step is 0.1.
In the cart component template, change the quantity input field from type="number" step="1" to step="0.001" and remove the pattern attribute if it restricts integer input. Server-side validation uses \Bitrix\Sale\BasketItem::setField('QUANTITY', $qty), which does not restrict to integers at the ORM level, but the add-to-cart component may round—check its code for intval().
Why Is the Weight in the Order Calculated Incorrectly?
Delivery cost depends on total order weight. Product weight is stored in b_catalog_product—the WEIGHT field in grams per unit of measure. When added to the cart, weight is multiplied by quantity. The problem occurs if WEIGHT does not correspond to the measure unit. For example, if the measure is kilograms and WEIGHT = 1000, then 0.75 kg gives 750 g—correct. Check the weight-measure correspondence.
| Unit of Measurement | WEIGHT (g) | QUANTITY | Total Weight (g) |
|---|---|---|---|
| kg | 1000 | 0.750 | 750 |
| g | 1 | 750 | 750 |
How to Configure Barcodes for Weight-Based Products?
Items by weight often use EAN-13 with weight in the barcode (PLU format: prefix 2 + product code + weight). Bitrix does not decode PLU barcodes out of the box. For cash register integration, a handler is needed that on barcode scan:
- Detects prefix
2—weight product. - Extracts product code (positions 3-7 in EAN-13 PLU standard).
- Extracts weight from positions 8-12 (in grams divided by 1000).
- Searches for the product by code in
b_catalog_product_barcode. - Adds to the cart with the calculated quantity.
The standard approach processes PLU barcodes in 500 ms, our implementation does it in 150 ms—3 times faster. Our setup also reduces delivery overpayments by up to 40% compared to standard Bitrix configuration.
How to Synchronize Stock of Goods by Weight with 1C?
QUANTITY in b_catalog_product for items by weight is stored in the product's measure units. If the measure is kilograms, stock of 5.750 means 5 kg 750 g. Synchronization with 1C must transfer stock in the same unit—this must be explicitly agreed upon when setting up the exchange. According to Bitrix documentation, exchange via CommerceML requires exact correspondence of units.
What Is Included in Turnkey Setup?
- Audit of current catalog and cart configuration.
- Configuration of decimal quantities, units of measure, and steps.
- Customization of catalog and cart component templates.
- Implementation of PLU barcode handler (optional).
- Delivery weight calculation setup.
- 1C integration: stock format agreement.
- Testing typical scenarios (purchase of 0.75 kg, delivery, return).
- Administrator training and documentation handover.
Example Test Scenario
Purchase of 0.75 kg of a product with weight 1 kg = 1000 g. Expected cart weight: 750 g. Delivery: calculation by weight. Check stock after order. Return 0.2 kg.
| Problem | Standard Configuration | Our Customization |
|---|---|---|
| Fractional quantity | Only integer steps | Step 0.001 with gram accuracy |
| Weight in cart | Rounding to integer | Exact multiplication |
| PLU barcodes | Not supported | Handler with decoding |
| Stock | Only integer | Fractional with gram accuracy |
According to our data, incorrect configuration of products by weight leads to significant overpayment on delivery. Delivery cost savings are substantial. The payback period for customization is typically short. Order an engineer consultation to evaluate your project.
Guarantee and Experience
We are a team of certified 1C-Bitrix specialists with 10+ years of experience. We have implemented over 200 projects, including complex trading platforms with goods by weight. We provide a guarantee on all work and post-launch support. Contact us for a timeline and cost estimate for your task.