Carbon footprint in your online store: how to calculate it and communicate it without greenwashing

Putting “carbon-neutral shipping” in the cart is easy. Backing it up, not so much. European regulations have greatly tightened what a store can say about the environmental impact of what it sells, and the line between informing and greenwashing is finer than it seems.

This guide explains how to estimate the carbon footprint of your products and orders, how to report it and which claims to avoid.

What a product's carbon footprint is

It is the sum of greenhouse gases emitted over its life, expressed in CO₂ equivalent (CO₂e): a common unit that converts methane, nitrous oxide and other gases into their equivalent effect in CO₂.

For an online store, an order's footprint has three parts:

• The products: raw materials, manufacturing and transport to your warehouse.
• The packaging: cardboard, plastic, filler.
• The shipment to the customer: it depends on the distance, the weight and the means of transport.

Where to get the data

There are two possible sources, and they should always be kept apart:

1. The manufacturer's figure. Some manufacturers publish the footprint of their products, sometimes with a life cycle assessment or an environmental product declaration. It is the most reliable figure you will have.
2. An estimate. When there is no figure, it can be estimated with average factors (by weight, by material, by category). It is useful to give an order of magnitude, but it is an approximation, and that has to be stated.

For shipping, the estimate usually starts from the distance (by country, by postcode or by carrier) and the weight, with emission factors per type of transport.

How to show it to the customer

• On the product page, with the footprint per unit and its source.
• In the cart, the order's total footprint, broken down into products, packaging and shipping.
• With understandable equivalents (kilometres by car, for example), making it clear that they are indicative.
• Without hiding the uncertainty: a figure with three decimal places suggests a precision that an estimate does not have.

What European regulations say

Directive (EU) 2024/825, on empowering consumers for the green transition, amended the Unfair Commercial Practices Directive and the Consumer Rights Directive. Among other things, it considers the following unfair in all circumstances:

• Generic environmental claims (“eco-friendly”, “environmentally friendly”, “green”) when recognised excellent environmental performance cannot be demonstrated.
• Claiming that a product has a neutral, reduced or positive impact on emissions based on offsetting emissions.
• Presenting as an advantage something that is a legal requirement for all products in the category.
• Using sustainability labels that are not based on a certification scheme or established by public authorities.

In practice, this rules out messages such as “carbon-neutral order because we offset its emissions”. What you can say is that you offer to offset the estimated emissions, how much it costs and which project it goes to, without claiming that the order has no impact.

Offsetting is not reducing

Offsetting consists of funding projects that absorb or avoid emissions elsewhere. It can make sense, but it does not make the order's emissions disappear. If you offer it:

• Make it voluntary for the customer, or cover it yourself and say so.
• Explain how the amount is calculated.
• State where the money goes and, if you have it, the project's standard.
• Never present it as “neutrality”.

The actions that really reduce the footprint are less eye-catching: tighter packaging, grouping shipments, pickup points, carriers with lower-consumption fleets. They are also the easiest to communicate without risk, because they are facts.

Common mistakes

1. Home-made “eco” seals with no certification behind them.
2. “Carbon-neutral shipping” based solely on offsetting.
3. Figures with no source or method.
4. Presenting an estimate as if it were a certified assessment.
5. Comparing with “the competition” without comparable data.
6. Calculating only the shipping and presenting it as the order's footprint.

Checklist

• Ask your suppliers for whatever footprint data they have.
• Flag which figures come from the manufacturer and which are estimated.
• Review all the texts in your store for “eco-friendly”, “green” or “neutral”.
• If you offer offsetting, explain the calculation and do not talk about neutrality.
• Keep the calculation method: if someone asks, you have to be able to explain it.

Frequently asked questions

Am I obliged to show the carbon footprint? A small store, in general, is not. But if you decide to show it or make any environmental claim, it has to be backed up. It is a case where saying nothing is less risky than saying something inaccurate.

Can I say my packaging is recyclable? Yes, if it really is and you say so specifically: “cardboard box recyclable in the blue bin” is a specific, verifiable claim. “Eco-friendly packaging” is generic.

Is an estimate by weight enough? To give an order of magnitude and help the customer compare, yes, as long as you say it is an estimate. To claim that one product pollutes less than another, no.

What do I do with products that have no physical footprint? Courses, services or gift cards: the most honest approach is not to show an invented footprint. Better to disable it on those products.

How to handle it in PrestaShop

RKR Huella de carbono calculates the footprint (CO₂e) of each product and each order —products, packaging and transport— and shows it on the product page, in listings and in the cart. If the manufacturer gives you the figure, you enter it per product or per combination; if not, it estimates it by weight with an adjustable factor, and the product page indicates whether it is a “manufacturer's value” or “estimated by weight”. The shipping distance is calculated by country, by postcode or by carrier, and the customer can offset the footprint from the cart, with a line on the order for the exact amount, or you can cover it yourself. The module itself presents it as an indicative estimate, not a certification, which is exactly the approach the regulations require.

This article is for information only and does not replace legal advice. Before using an environmental claim in your store, check it with a professional.