Sell by weight or by the metre in PrestaShop.

How to sell by weight or length in PrestaShop

PrestaShop counts in whole units. Common workarounds are combinations such as 250 g, 500 g and 1 kg, or a module that changes the price but leaves the quantity at 1. Combinations limit customers to fixed sizes and multiply your stock lines.

Sell by Weight & Length lets customers type the amount they need: 1.25 kg of coffee, 2.40 m of fabric, 3.5 m² of flooring, 0.75 L of paint. Prices go through PrestaShop’s own calculation, so specific prices, catalog price rules, group discounts, taxes and currencies keep working, with no overrides.

What customers see

1. The product page shows the price with "/ kg", an amount field with − and + buttons, quick amounts such as 250 g and 1 kg, and the limits, such as "Min. 0.10 kg · max. 5.00 kg · steps of 0.05 kg". It replaces the theme’s quantity field.
2. A live total shows "Total $14.88 (1.25 kg × $11.90 / kg)".
3. Each amount is its own cart line, with "Weight: 1.25 kg" and "Price per kg: $11.90".
4. The amount appears in checkout, order confirmation, order history, e-mails and PDF invoices, and on the back-office order page.

Adding the same amount again raises that line’s quantity, so 2 × 1.25 kg is two pieces of that amount. The cart quantity field counts pieces of an amount, and a different amount is a new line.

On product lists, "/ kg" shows after the price. Themes with an add-to-cart button in lists, such as Hummingbird, show See details instead, because an amount is needed.

Setting up a product or a whole category

In the product’s Modules tab, open Sell by Weight & Length and click Configure. The block saves on its own.

There are 15 units: kg, g, lb, oz, m, cm, ft, yd, in, m², ft², L, ml, gal and fl oz.

For a department, set Category defaults on the module page. Products set to Use the category default take the rule of their default category, then its parents, then their other categories. Choose Whole items to exempt a product.

Combinations use the settings of their product, and each combination’s price and weight impact applies per unit. PrestaShop’s own Stocks quantity shows exact stock rounded up, so 12.35 shows as 13. Orders reduce stock exactly, and cancellations restore it. Weight-based carriers get the real shipping weight.

What to expect

• PrestaShop stores whole quantities, so a measured line is one piece of 1.25 kg. The amount is part of the line, and two pieces of the same amount show quantity 2.
• Packs and virtual products are not sold by measure.
• A product has one sale unit, so sell a pre-packed and a loose version as separate products.

If you only sell three pack sizes, combinations are free and simpler. Choose real amounts when customers order what they need.

Works well with

The Pantry theme shows Choose amount on cards and styles the amount field; the Pantry Store Kit bundles both. EU E-Invoicing carries measured quantities with their unit. Product Personalizer works on the same cart line. The Made-to-Order Pack is on the packages page. Our guide compares options across platforms. Get Sell by Weight & Length on the store.

Compatibility

One package for PrestaShop 8.2 and 9.x, on Classic and Hummingbird, tested with the 9.2 one-page checkout. One small script loads on product pages only. No overrides.

Example setups by product type

Match the step to how you actually weigh and cut. A step of 0.001 kg promises what your scales may not deliver. Before launch, order one product on your live payment method, change the amount, cancel the order, and check that stock returns. Then check the PDF invoice, which is the document your customer keeps.