A Natural Origin Index is a number, calculated under the international standard ISO 16128, that says how much of a product’s formula comes from natural sources. Each ingredient is sorted into a category (natural, derived natural or non-natural), given an index between 0 and 1, and weighted by how much of it is in the formula. Every Furrytail formula has a Natural Origin Index of 99.5%, calculated under ISO 16128-2. The number describes where ingredients come from. It is not a safety rating or a certification.
What is ISO 16128?
ISO 16128 is an international standard for natural and organic cosmetic ingredients and products. It has two parts:
- ISO 16128-1 defines the ingredient categories: what counts as natural, derived natural or non-natural (and the organic equivalents).
- ISO 16128-2 sets out how to calculate the indexes for an ingredient and for a finished product.
It was written for cosmetics, and pet-grooming brands increasingly use it too, because it is one of the few shared, published methods for putting a number on “natural”.
How are ingredients sorted?
In broad terms, ISO 16128-1 puts every ingredient into one of three groups:
- Natural ingredients: from plants, animals, microorganisms or minerals, obtained by physical processes such as pressing or distilling, or by fermentation. Water counts here.
- Derived natural ingredients: natural ingredients that have been chemically processed, where more than half of the molecule still comes from a natural source. Many gentle cleansers, such as amino acid-derived surfactants, sit in this group.
- Non-natural ingredients: made from petrochemical or other non-natural starting materials.
How is the Natural Origin Index calculated?
Under ISO 16128-2, each ingredient gets an index:
- a natural ingredient counts as 1
- a derived natural ingredient counts for the share of it that is of natural origin, worked out by the standard’s methods
- a non-natural ingredient counts as 0
The product’s Natural Origin Index is the weighted total: each ingredient’s index multiplied by how much of it is in the formula, added up. A 99.5% index means that, calculated this way, 99.5% of the formula is of natural origin.
A simple illustration (not a real formula): a product that is 80% water, 15% natural plant extracts and oils, 4.5% derived natural ingredients that are entirely of natural origin, and 0.5% non-natural ingredients would score 80 + 15 + 4.5 + 0 = 99.5%.
Why does water matter?
Water is a natural ingredient, and in most shampoos and sprays it is the biggest one. Including it lifts the index, so ISO 16128-2 allows the index to be calculated with or without water and expects the basis to be clear. When you compare two “natural origin” percentages, ask whether both were calculated the same way. A brand should be able to tell you.
What doesn’t a Natural Origin Index tell you?
The standard is deliberately narrow. A Natural Origin Index:
- is not a safety rating. ISO says the standard doesn’t address safety, and natural ingredients can irritate too.
- is not a certification. It is a calculation method; ISO doesn’t certify products against it or issue a logo for it.
- doesn’t mean nothing synthetic is inside. 99.5% leaves 0.5%, and derived natural ingredients are chemically processed by definition.
- doesn’t measure how well a product works, how it smells or whether it suits your pet.
That’s why we print the Nothing List, what we left out, and the full ingredient list on every pack, alongside the number. Our longer article what does “natural” actually mean in pet care? covers natural claims more broadly.
How should I read “natural” on a pet product?
- Look for a number and a standard. “99.5% natural origin (ISO 16128-2)” says how it was measured. “Natural” on its own doesn’t.
- Check the ingredient list. The INCI shows what is actually in the bottle. See reading an INCI list.
- Check what’s left out. A “what’s out” list tells you about the ingredients you might want to avoid.
- Check it’s made for your pet. Species, pH and fragrance matter more than any percentage.
What does 99.5% mean on Furrytail products?
Every Furrytail formula, from the Gentle Daily Shampoo to the Dry Foam Shampoo and Paw Cleaner, has a Natural Origin Index of 99.5% calculated under ISO 16128-2. It tells you where the ingredients come from. What it can’t tell you, we print next to it: what we left out, and every ingredient that’s in, by name. Our brand facts page sets out the rest.
