If you sell to consumers in the EU or the UK and your product is priced by weight, volume, length or area, your online shop has to show a unit price — the price per kilogram or per litre — next to the selling price. Directive 98/6/EC is blunt about it in Article 3(1): "The selling price and the unit price shall be indicated for all products referred to in Article 1", and Article 3(4) extends the same duty to "any advertisement which mentions the selling price" (consolidated text of 28 May 2022, EUR-Lex, checked July 2026). The United States has no federal equivalent — unit pricing is mandatory in ten jurisdictions and voluntary everywhere else.
We ended up reading these texts line by line because By-Weight Pricing for WooCommerce prints a per-kilogram figure next to a price, and "per kilogram" is not the same obligation in Berlin, Paris and Manchester. Everything below is taken from the official sources — EUR-Lex, gesetze-im-internet.de, Légifrance, legislation.gov.uk and NIST, all checked in July 2026 — together with the places WooCommerce leaves a store exposed. It is general information, not legal advice for your market.
What is a unit price, and how is it different from the selling price?
The unit price is the final price, including VAT and all other taxes, for one kilogram, one litre, one metre, one square metre or one cubic metre of the product — that is the definition in Article 2(b) of Directive 98/6/EC. The selling price, defined in Article 2(a), is the final price for the pack as it is actually sold.
The distinction only matters because shoppers can't do the arithmetic at a glance. A 300 g jar at €8.97 and a 500 g jar at €13.90 look close together until both carry their unit price: €29.90/kg against €27.80/kg. Germany calls this second figure the Grundpreis, France the prix à l'unité de mesure, the UK simply the unit price — same idea, three different sets of rules about which unit you may use. Where the customer chooses the quantity instead of a pack, the per-kilogram figure stops being a comparison aid and becomes the price itself, which is a different build entirely: how to sell by weight in WooCommerce covers the four methods and where each one breaks.
Which countries require a unit price in an online shop?
Every EU member state and the UK require it for consumer sales; the US requires it in ten jurisdictions. Here is the shape of the obligation in the markets most WooCommerce stores sell into.
| Jurisdiction | Legal basis | Unit required | Applies online | Notable exemptions |
|---|---|---|---|---|
| EU (all member states) | Directive 98/6/EC, consolidated 28 May 2022 | 1 kg, 1 L, 1 m, 1 m², 1 m³, or a customary national unit | Yes, including any ad that states a price (Art. 3(4)) | Unit price identical to selling price (Art. 3(1)); national waivers under Art. 5(1) |
| Germany | PAngV 2022, §§ 4–5 | Packaged: 1 kg / 1 L / 1 m³ / 1 m / 1 m² only. Loose: 1 kg or 100 g, 1 L or 100 mL | Yes | Under 10 g or 10 mL; mixed assortments; farm shops, kiosks and market stalls; vending machines (§ 4(3)) |
| France | Code de la consommation Art. L112-1 + arrêté du 16 novembre 1999 | Kilogram or hectogram (100 g); litre or decilitre — one unit per product category | Yes | Packs whose net quantity already equals the unit (Art. 6) |
| UK (Great Britain) | Price Marking Order 2004, amended 2024 and 2025 | 1 kg, 1 L, 1 m, 1 m², 1 m³, plus special units in Schedule 1 | Yes | "Small shop" of 280 m² or less, for certain pre-packed products |
| United States | No federal law; NIST Handbook 130 model regulation | Per state rules, imperial or metric | Depends on the state | Mandatory in 9 states plus the District of Columbia; voluntary elsewhere |
Three of those regimes moved recently, which is why guidance written before 2023 is worth distrusting.
28 May 2022
Germany's rewritten PAngV takes effect: § 5(1) prescribes 1 kg or 1 L for packaged goods, with no small-pack alternative.
28 May 2022
The Omnibus-amended consolidation of Directive 98/6/EC applies across the EU, with strengthened penalty regimes.
1 July 2024
France's arrêté du 16 avril 2024 requires stores over 400 m² to flag shrinkflation, naming the changed price per unit.
6 April 2026
Great Britain's Price Marking (Amendment) Order 2024 finally commences, after SI 2025/592 pushed it back from 1 October 2025.
What does EU law actually require?
Five provisions of Directive 98/6/EC carry almost all the weight, and each one is short enough to quote.
- Both prices, always. Article 3(1) requires the selling price and the unit price for all products offered by traders to consumers, and allows the unit price to be dropped only when "it is identical to the sales price".
- Bulk goods get one price. Article 3(3): "For products sold in bulk, only the unit price must be indicated." If a customer chooses the quantity, the per-kilogram price is the price.
- Legibility is part of the duty. Article 4(1) demands that both prices be "unambiguous, easily identifiable and clearly legible". A unit price hidden in a tab, a tooltip or a product image does not satisfy that.
- Advertising counts. Article 3(4) catches any advertisement that mentions the selling price — newsletters, price-bearing social ads, and the product feeds that also feed AI shopping agents reading your WooCommerce catalog.
- Member states can carve out. Article 5(1) lets a state waive the unit price where it "would not be useful because of the products' nature or purpose or would be liable to create confusion".
A directive binds through national law, so the operative detail — which unit, which exemptions — lives in each member state's implementation. Two of those matter disproportionately for stores selling by weight.
What changed in Germany's PAngV, and why does it catch stores out?
The unit for packaged goods is now 1 kilogram or 1 litre with no small-pack alternative, and that is the single most common German compliance error we see on WooCommerce stores. § 5(1) of the Preisangabenverordnung in force since 28 May 2022 lists 1 Kilogramm, 1 Liter, 1 Kubikmeter, 1 Meter and 1 Quadratmeter — and nothing else for packaged products. The only place 100 g and 100 mL survive is § 5(2), which covers lose Ware sold unpackaged by weight or volume.
The obligation itself sits in § 4, split cleanly by how the goods are sold:
- § 4(1) — goods in Fertigpackungen, open packs or sales units without wrapping must show the Grundpreis alongside the Gesamtpreis "unmissverständlich, klar erkennbar und gut lesbar", unless the two are identical.
- § 4(2) — for loose goods offered by weight, volume, length or area, only the Grundpreis is required.
- § 4(3) — the exemption list: products under 10 g or 10 mL, non-blended assortments, small direct sellers such as farm shops, wineries and market stalls, vending machines, small quantities of chewing and snuff tobacco, certain colour cosmetics and perfumes.
Germany is also where the consequences arrive fastest. Missing base prices are an administrative offence, but the practical risk is the Abmahnung — a cease-and-desist letter from a competitor or a consumer association, with costs attached, over a figure that was never rendered. One more trap: the Grundpreis has to correspond to the price actually charged, so a sale price has to produce a recalculated base price, not the regular-price one. Deriving the figure from the product's current price rather than storing it is what makes that automatic — the three ways to render a price per kg in WooCommerce compares them.
Kilogram or 100 g — which unit does France require?
France lets you choose, then holds you to the choice. Article 1 of the arrêté du 16 novembre 1999 requires pre-packaged products to show the selling price per kilogram, hectogram, litre, decilitre, metre, square metre or cubic metre — so a retailer may use €/kg or €/100 g, and €/L or €/dL, but must apply a single unit consistently across a product category. Mixing €/kg on one cheese and €/100 g on the next is the failure mode.
Article 6 exempts pre-packaged products whose net quantity already equals one of those units — an exact 1 kg pack needs no separate unit price, because the pack price is the unit price.
Since 1 July 2024 there is a second layer. The arrêté du 16 avril 2024 obliges retailers with a sales area above 400 m² to flag shrinkflation on pre-packaged goods whose quantity fell while the price per unit rose, with a notice naming the old and new quantities and the percentage increase in the unit price. It applies to physical stores rather than online shops, but it has made French shoppers considerably more attentive to the per-kilogram figure.
What changes in the UK on 6 April 2026?
Loyalty and member prices will need their own unit prices, promotional reductions will need reduced unit prices, and legibility gets an explicit font requirement. Those changes come from the Price Marking (Amendment) Order 2024, whose commencement SI 2025/592 moved from 1 October 2025 to 6 April 2026 — Article 2(2) simply substitutes the new date.
The baseline is still the Price Marking Order 2004: Article 5 requires a unit price for products sold from bulk and for pre-packed products that must be quantity-marked; Article 1(2) defines the unit price as the final price including VAT per kilogram, litre, metre, square metre or cubic metre; Article 7 requires indications to be "unambiguous, easily identifiable and clearly legible" and placed near the product. A "small shop" — a relevant floor area of 280 m² or less — is exempt for certain pre-packed goods, a concept that does not translate to an online catalogue, so no e-commerce seller should lean on it.
What SI 2024/1055 adds is worth planning for now:
- a new Article 7A: where a product is offered at more than one price, each selling price and each unit price must be shown, along with the conditions for accessing them;
- amended Article 9: a general reduction must show "the reduced selling price and the reduced unit price";
- amended display rules: prices must be legible and "displayed using a font which is clear and of reasonable size";
- deposit amounts under a deposit return scheme are excluded from both the selling price and the unit price.
If you run member pricing or frequent promotions on a GB-facing store, that is a template change, not a settings change — budget for it before April.
Is unit pricing required in the United States?
Only in ten jurisdictions, and it is voluntary in the rest. NIST publishes the model law — the Uniform Unit Pricing Regulation in Handbook 130 — which states adopt at their discretion. Per NIST's guide to US retail pricing laws (checked July 2026): "Ten (10) of these have mandatory unit pricing provisions. They are: Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont and the District of Columbia."
For a US WooCommerce store, that makes the per-pound or per-ounce figure optional in most of the country and mandatory across much of the Northeast. It is still worth showing everywhere: a unit price is the cheapest way to prove you are not hiding a smaller pack behind a familiar price.
How do you show a price per kg in WooCommerce?
WooCommerce core cannot do it — the product weight field feeds shipping calculations and never appears next to the price, and there is no unit-price field anywhere in the product data panel. Compliance therefore means either template work in woocommerce_get_price_html or a plugin that computes the figure from each product's price and weight.
Whichever route you take, the same six things decide whether the result is compliant:
- Unit price rendered next to the selling price on product pages, shop and category listings — not in a tab or tooltip
- Correct legal unit per market: 1 kg / 1 L for German packaged goods, one chosen unit per category in France
- Base price recalculated from the sale price whenever a promotion runs
- Variable products showing a unit price per variation, not one figure for a whole price range
- Both prices inclusive of VAT and all other taxes
- Product feeds carrying unit-pricing attributes, since price-bearing ads are in scope
By-Weight Pricing handles the first four by deriving the per-kilogram figure from each product's current WooCommerce price, so a sale price automatically yields a reduced base price, and by supporting 40-plus weight units with automatic gram-to-kilogram switching for stores that need €/kg in Germany and £/kg in Great Britain. Its live weight-to-price calculator covers the bulk case in Article 3(3), where the customer picks the quantity and the per-kilogram price is the price. It is translation-ready rather than tied to one multilingual stack.
The last row is the one stores forget. Article 3(4) puts advertisements in scope, so a Shopping feed that states a price for an EU or UK audience should carry unit_pricing_measure and unit_pricing_base_measure — the same discipline that makes a Merchant Center feed usable in the AI shopping era. Getting the storefront right and leaving the feed silent solves half the problem.
FAQ
Do I have to show a price per kg in my online shop?
In the EU and the UK, yes — consumer-facing products sold by weight, volume, length or area must show a unit price next to the selling price, under Article 3(1) of Directive 98/6/EC, § 4 of the German PAngV and Article 5 of the UK Price Marking Order 2004. In the United States it depends on the state: NIST lists nine states plus the District of Columbia as having mandatory unit pricing.
Is a price per 100 g still allowed in Germany?
Only for loose goods sold unpackaged by weight or volume, where § 5(2) PAngV permits 1 kg or 100 g and 1 L or 100 mL. For packaged goods, § 5(1) of the Preisangabenverordnung in force since 28 May 2022 lists only 1 kilogram, 1 litre, 1 cubic metre, 1 metre and 1 square metre, with no small-pack alternative.
Does the unit price have to change when a product is on sale?
Yes — the base price must correspond to the price actually charged, so it has to be recalculated from the sale price rather than the regular one. In Great Britain this becomes explicit on 6 April 2026, when the amended Article 9 of the Price Marking Order requires a general reduction to show both the reduced selling price and the reduced unit price.
Does WooCommerce show unit prices out of the box?
No. The WooCommerce product weight field feeds shipping calculations only and never appears beside the price, and there is no unit-price field in the product data panel. Showing a price per kilogram requires either custom code hooked into the price HTML or a plugin that derives the figure from each product's price and weight.