How Is the Percentage of Recycled Plastic in Products Really Measured: ISO Standards, European Rules, Supply Chain Audits, Mass Balance and Digital Watermarks in the New EU Packaging Landscape

Author: Marco Arezio. Expert in the circular economy, polymer recycling and industrial plastics processing. Founder of the rMIX platform, dedicated to enhancing the value of recycled materials and developing sustainable supply chains.

Date: March 26, 2026

Reading time: 16 minutes

Introduction

Saying that a package “contains recycled plastic” is easy. Proving it in a serious, repeatable and defensible way before customers, authorities, auditors and the market is much more difficult. And today this difference matters more than before, because plastic is at the center of Europe’s new circularity policies: packaging accounts for about 40% of the plastic used in the Union and, in 2022, each European citizen generated 186.5 kg of packaging waste. The new European Packaging and Packaging Waste Regulation, the PPWR, entered into force on February 11, 2025, and its general date of application is set for August 12, 2026; among its objectives are increasing the safe use of recycled plastic and ensuring the recyclability of all packaging by 2030.

The real question, therefore, is not only how much recycled plastic is in a product, but how it is actually proven. The correct answer is less intuitive than it may seem: in most cases, the percentage of recycled content cannot be read “by eye” nor certified with a single laboratory test on the finished item. Instead, it is built through a combination of regulatory definitions, mass balances, supply chain traceability, volume reconciliation, third-party audits and, increasingly, digital tools that improve the separation and qualification of incoming waste.

What “recycled content” really means

The technical basis starts with the definition. In the ISO field, recycled content is defined as the proportion, by mass, of recycled material present in a product. ISO 14021 remains one of the key references today for self-declared environmental claims and also includes the terms related to “pre-consumer material” and “post-consumer material,” that is, the distinction between material recovered before use by the final consumer and material coming from post-consumer waste.

This point is decisive, because many market ambiguities arise here. A producer may declare 30% recycled content, but it is necessary to understand whether that 30% comes from internal or external industrial scrap, from urban post-consumer waste, from selected commercial waste, or from a combination of the two. From the point of view of environmental communication, the difference is not secondary: the technical quality of the material, the circular value of the claim and its market perception change significantly depending on the origin of the recycled content. ISO 14021 provides precisely this terminological and methodological framework to avoid vague or misleading claims.

How the percentage of recycled plastic is calculated

The basic principle is simple: it is a mass ratio. In the most straightforward case, the percentage of recycled content corresponds to the mass of recycled plastic incorporated into the product divided by the total mass of plastic considered within the scope of the claim, multiplied by 100. For single-use plastic bottles, the European Commission has already set specific rules: Implementing Decision 2023/2683 establishes that the proportion of recycled plastic is calculated by dividing the weight of recycled plastic in the bottles placed on the market by the total weight of the bottles placed on the market.

But the formula alone is not enough. It is necessary to define the calculation perimeter precisely: batch, line, plant, annual period, product category, specific packaging family. It is also necessary to know which process losses were considered, which additives or masterbatches enter the formulation, and how the quantities coming in and going out are reconciled. Audit schemes based on EN 15343 and the most widely used traceability certifications require exactly this: documentary evidence, identification of flows and a plausibility check between inputs, yields, losses and declared output.

Why the laboratory is almost never enough

Here we enter the heart of the problem. In theory, the laboratory is essential to identify the polymer, measure impurities, assess contaminants, verify MFI, ash, density, migration, odors or stability. In practice, however, the laboratory is almost never sufficient, on its own, to certify the exact percentage of recycled plastic contained in a finished product. The European Commission itself, in the section dedicated to the recycling of plastics intended for food contact, explains that the composition of recycled plastic cannot easily be subjected to official controls as happens with virgin plastic and that, precisely for this reason, controls focus on the production of recycled material and on audits of installations.

The same approach also emerges from the technical literature of the European JRC in other highly regulated sectors: the verification of the content of recycled materials is described as based exclusively on documentation, with calculation rules, blending rules and measurement points defined upstream. In other words, the laboratory serves to qualify the material; the declared percentage, on the other hand, is demonstrated above all through chain of custody. This is an essential distinction for understanding why so many commercial declarations prove fragile when a robust traceability structure is missing.

European traceability: EN 15343 as the cornerstone

In the European context, EN 15343 is the cornerstone standard for recycled plastic. The standard specifies the procedures necessary for the traceability of recycled plastics and provides the basis for calculating the recycled content of a product. This means that the declared percentage does not arise from a qualitative perception of the material, but from a documented supply chain: origin of the waste, transformation, batch identification, internal controls, volume reconciliation and consistency between inputs and outputs.

The certification schemes applied by the market move in exactly this direction. RecyClass, for example, explicitly states that its traceability certification verifies the exact percentage of recycled content through a controlled blending approach aligned with EN 15343 and ISO 22095; it also предусматриes third-party on-site audits and annual renewal of the certificate. This is important because it distinguishes a simple commercial self-declaration from an audited and defensible declaration.

Mechanical recycling: the clearest case, but not a trivial one

In mechanical recycling, the measurement of recycled content is generally more straightforward than in other scenarios. The recycled material enters as ground material, flakes or pellets; it is mixed with possible virgin material, additives or colorants; then it is transformed into the final product. In this case, the percentage can be demonstrated through a combination of purchase documents, supplier certificates, production sheets, compound recipes, mass balances and checks on the quantities actually processed, taking losses into account. Process audits require precisely a reconciliation of volumes to verify that the output corresponds to the recycled input used, considering yields, losses and additives.

However, risks also exist here. If the incoming recycled material is not itself traceable or if it comes from poorly qualified heterogeneous streams, the numerical percentage may be correct on paper but weak in substantive terms. In other words, “50% recycled content” does not always have the same value: it matters whether it is truly traceable post-consumer PCR, pre-consumer industrial scrap, food-grade material, or a mixed stream with high qualitative uncertainty. For this reason, the strongest companies do not limit themselves to weighing the material, but document the origin and quality of the recycled content used.

Food contact: when proof shifts even more toward the process

In food packaging, the issue becomes more rigorous. The European Commission points out that, when plastic is recycled for food-contact use, the problem is not only quantifying the recycled content but ensuring that any chemical contaminants have been removed to safe levels. Precisely because such contaminants may be unknown or variable, official control focuses not so much on the analysis of the finished product as on the decontamination process, good manufacturing practices and plant audits.

This is also a crucial point for marketing communication. If a food container declares a certain recycled content, the credibility of that declaration depends not only on the numerical percentage, but on the ability to demonstrate that the recycled content was obtained within an authorized, monitored process suitable for the intended use. In food packaging, therefore, the “how much” and the “how” cannot be separated.

Chemical recycling and mass balance: the most delicate issue

When chemical recycling is involved, the matter becomes more complex because plastic waste is transformed into feedstock that is mixed with conventional raw materials in complex industrial systems. In these cases, the physical segregation of the “recycled” atom is not realistically practicable throughout the chain. For this reason, mass balance models are used, that is, chain of custody models that allocate a share of recycled content to outputs on the basis of accounting, temporal and allocation rules, without exceeding the quantity of recycled input that actually entered the system. ISCC PLUS describes this approach as one of the chain of custody options, alongside physical segregation and controlled blending.

The issue is so central that ISO has also published ISO 22095-2:2026, specifically dedicated to the requirements and guidelines for applying the mass balance model in chain of custody systems. This is an important signal: mass balance is becoming less and less a mere “market” practice and increasingly an area of technical standardization.

On the European regulatory level, the matter is still very much open. In July 2025, the Commission launched a consultation on new rules to calculate, verify and report chemically recycled content in single-use plastic beverage bottles. The proposed methodology is based on the fuel-use excluded allocation rule, meaning it excludes from recycled content any share of waste destined for fuels or energy recovery; it also provides for annual third-party verification for the most complex stages of the chemical supply chain and lighter requirements for SMEs.

The new technology that can truly change European packaging

When people talk about recycled plastic, many imagine that there is a machine capable of taking a finished package, analyzing it and saying with precision: “there is 37% recycled plastic in here.” In industrial reality, that is not how it works today.

The technology that can truly change European packaging is not a laboratory test capable of magically reading the recycled content of every package, but a system that helps separate packaging waste better before it is recycled. This system is based on digital watermarks, that is, small invisible or almost invisible codes printed on the package.

To understand what this means, let us imagine a plastic tray for food, a detergent bottle and a cosmetic container. Today, when these packages arrive at a sorting plant, automatic systems can identify the type of plastic fairly well, for example PET, HDPE or PP, but they often have more difficulty distinguishing the original use of the package, that is, whether that plastic came from a food, cosmetic or household application. And this difference is very important, because plastics that appear similar may require different recycling pathways.

This is where digital watermarks come into play. In practice, every package can carry with it a sort of “digital identity card” that can be read by sorting systems. This identity can tell the plant: “I am a food tray,” “I am a detergent bottle,” “I am a PP package,” “I belong to a certain category.” Thanks to this information, waste can be sorted much more precisely than with traditional systems.

This is the real change: recycling is not improved at the end of the process, but at the beginning, when the waste is separated. If you start with a cleaner, more homogeneous and better classified stream, the recycled material obtained at the end will also be better.

To make this even more concrete, one can think of the difference between collecting all fruit together in one large bin or separating it immediately by type and quality. If everything is mixed, the final result is a product that is less controllable. If, instead, separation is done properly at the origin, the final result is cleaner, more consistent and more suitable for quality uses. The same thing happens with plastic.

This is why this technology is of such great interest to European packaging. Europe’s main problem, in fact, is not only recycling more, but recycling better. Much recycled plastic today has variable quality because it comes from waste streams that are too mixed and difficult to distinguish accurately. If sorting can be improved, the result is a purer, more stable and more reliable PCR, that is, post-consumer recycled plastic.

This also has a very important consequence on the regulatory and commercial level. When a company declares that a package contains a certain share of recycled plastic, it must be able to prove it credibly. If the recycled material comes from a cleaner, traceable and well-separated supply chain, that declaration becomes more robust. In other words, digital watermarks are not used to directly “measure” the recycled content of the finished package, but to build a more reliable recycling chain, and therefore to make declared percentages more credible as well.

From a practical point of view, their advantage is threefold. First: they help plants distinguish packaging better. Second: they make it possible to produce higher-quality recycled material. Third: they make it easier to connect that recycled material to serious supply chain documentation, useful for audits, certifications and compliance with the new European rules.

So the central point is this: the technology does not change European packaging because it reads the recycled content already present in the product, but because it makes smarter, cleaner and more demonstrable recycling possible. And this is exactly what Europe needs today: not only more recycling, but recycling that can withstand technical checks, customer demands and future PPWR rules.

What Europe is really asking for today

On the regulatory front, Europe is moving on two levels. The first is the one already active for single-use plastic bottles: the SUP Directive requires 25% recycled plastic in PET bottles from 2025 and 30% in all plastic beverage bottles from 2030. The European Commission also recalls that in 2023 it adopted Implementing Decision 2023/2683 on the rules for calculating, verifying and reporting recycled content in single-use bottles.

The second level is the broader PPWR framework. The official pages of the Commission clarify that the regulation entered into force on February 11, 2025, will generally apply from August 12, 2026, aims to make all packaging recyclable by 2030 and requires plastic packaging to incorporate increasing shares of recycled content with targets for 2030 and 2040. In other words, the verification of recycled content is no longer a niche issue for brands sensitive to sustainability: it is becoming a compliance infrastructure for the European market.

How a company should really verify recycled content

If a producer wants to avoid greenwashing and prepare for the new European context, it should not only ask itself “how much recycled plastic am I using?” but also “how will I be able to prove it in an audit?” The correct answer today is to build a system composed of four elements: a clear definition of the claim according to recognized standards; traceability of incoming material; mass balance with volume reconciliation; independent third-party verification when the market or customer requires it. This approach is consistent with ISO 14021, EN 15343, RecyClass schemes and the logic of European verification rules for bottles and food contact.

In practical terms, a robust claim should specify at least three things: whether the recycled content is pre-consumer or post-consumer; which chain of custody model has been applied, that is, segregation, controlled blending or mass balance; which independent body has verified the system, if any. When this information is missing, the declared percentage may even be numerically correct, but it remains weak from an evidentiary point of view.

Conclusion

The percentage of recycled plastic in products is not really measured with a single machine and is not demonstrated with an isolated formula. It is verified through an architecture of proof: ISO definitions, European traceability standards, mass balances, plant audits, supply chain documentation and, in the more advanced cases, digital systems that improve the separation and quality of recycled material upstream. This is the point that many commercial communications tend to oversimplify.

The new technology that can change European packaging today is therefore not a “magic test” for reading recycled content in the finished item, but a technological ecosystem capable of making the supply chain more intelligent. Digital watermarks are probably the most concrete frontier in this direction, because they can increase sorting quality, create purer PCR streams and make future declarations about recycled content much more credible. In a European market that is moving from narrated sustainability to verified sustainability, this distinction will make the difference between those who communicate and those who prove.

FAQ

How is recycled content measured in plastic?

As a rule, it is measured as the proportion by mass of recycled material in the product, but actual proof comes above all through traceability, mass balances and supply chain audits, not through a single test on the finished product.

Is there a laboratory test that can say with certainty how much recycled plastic is in a package?

In general terms, no: European sources show that verification of recycled content is based above all on documentation and process control, while final analysis alone is not sufficient to establish the exact declared share in all cases.

What is the difference between pre-consumer and post-consumer?

Pre-consumer comes from scrap recovered before use by the final consumer; post-consumer, on the other hand, comes from waste generated after use by households or commercial activities. ISO 14021 explicitly distinguishes these categories.

What is mass balance in recycled plastic?

It is a chain of custody model used above all when recycled and conventional feedstocks are mixed in complex systems, as in chemical recycling. In that case, the recycled share is allocated to outputs according to accounting rules that can be verified.

Do digital watermarks measure recycled content?

Not directly. However, they improve the separation of packaging waste and the creation of purer, more traceable streams, an essential condition for producing quality recycled material and making verification of recycled content in future products more robust.

Real and verified sources

European Commission, Packaging waste and Packaging & Packaging Waste Regulation (PPWR), with data on entry into force, application date and objectives of the regulation.

European Commission, Single-use plastics, with targets on recycled content in bottles and the chronology of implementing acts.

European Commission, Plastic Recycling / Food Safety, with clarifications on controls, contaminants and the central role of process audits in food contact.

ISO, ISO 14021 and ISO references on chain of custody and mass balance.

European standard EN 15343, on the traceability of recycled plastics and the calculation of recycled content.

European Commission, 2025 consultation on rules for chemically recycled content in bottles, with the fuel-use excluded method and third-party verification.

AIM / HolyGrail 2.0 and HolyGrail 2030, on digital watermark technology and intelligent sorting results.

ISCC PLUS and RecyClass, for chain of custody models, controlled blending, mass balance and traceability audits.

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