Mass balance
Also searched as: mass-balance, mass balance chain of custody, volume reconciliation, credit-based claim, attributed content
A chain-of-custody accounting model in which certified and uncertified inputs may be physically mixed, while certified claims on outputs are capped by the verified quantity of certified input.
In detail
Under mass balance, a site records how much certified material enters a process during a defined period and allocates an equivalent quantity, adjusted for conversion losses, to outgoing products that may then carry the claim. The claimed output is connected to the same production process but need not contain the certified fibers or molecules themselves. This differs from segregation, where certified material is kept physically separate, and from book-and-claim, where credits are traded without any physical link. Mass balance tends to appear where continuous processes, such as polymer or pulp production, make physical separation impractical.
The science and numbers
The underlying rule is a conservation check over a site boundary and a reconciliation period: claimed output must not exceed certified input multiplied by a conversion factor, with opening balances, losses and carry-over recorded. Textile Exchange's Content Claim Standard 3.0, launched in June 2021, relies on batch-level segregation for both fully certified and blended products and limits the volume reconciliation period to no more than three months. Textile Exchange separately piloted a site-level mass-balance approach in 2021, in which sites generate credits from claimed inputs that may be assigned to outputs physically connected to production, and it has published an issue paper and a policy on alternative volume reconciliation. Auditors test any such system by reconciling purchases, production yields and sales against claimed quantities.
A practical example
A yarn plant runs recycled and virgin polyester chip through one continuous line. In a quarter it buys 300 tonnes of certified recycled chip and 700 tonnes of virgin chip. With a hypothetical 95 percent yield, a mass-balance model could let it assign recycled claims to about 285 tonnes of output, although every bobbin holds the same physical mixture. Under segregation it would instead need separate batches with measurable recycled content.
What to distinguish
A mass-balance claim is an accounting statement, not a description of what a particular item physically contains. A garment sold with a mass-balance recycled claim may hold little or no recycled material. Standards differ on whether mass balance is allowed at all, how long reconciliation periods may run, whether credits can move between sites, and how claims must be worded, so check the exact standard, version and claim language.
Origins and history
The term comes from engineering, where a mass balance applies conservation of mass to the inputs, outputs and accumulation of a defined system. Sustainability schemes borrowed it for claims accounting in commodity supply chains, such as palm oil, cocoa and forest products, where physical separation is costly. In textiles, interest has grown alongside chemical recycling and continuous polymer processes that do not suit batch segregation.
Related terms
Sources & further reading
- Textile Exchange: Content Claim Standard 3.0
- Textile Exchange: Issue paper, approach to volume reconciliation (2021)
- Textile Exchange: Policy for Alternative Volume Reconciliation (VR2)
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.