Methodology and data sources

Version 1.1, published 17 September 2026. Every change to this page is listed at the bottom.

This page explains what the Invoc app shows for a food product, where the data comes from, how comparison groups are formed and how products are ordered inside a group. It is written for shoppers, producers and brands alike. The information in the app describes products; it is not medical or dietary advice. Always read the label, in particular for allergens.

1. What the app shows for a product

Nutri-Score. The grade (A to E) as it appears in the Open Food Facts record of the product, where it is computed with the official Nutri-Score method published by Santé publique France. Invoc does not recalculate it and does not alter it. When the record carries no grade, the app shows none. Should Invoc ever compute a grade itself, that grade will be labelled as computed by Invoc.
NOVA group. The degree of processing, from 1 (unprocessed or minimally processed) to 4 (ultra-processed), according to the NOVA classification, as recorded in Open Food Facts.
Additive count. The number of additives found in the ingredient list of the record (E numbers and named additives). The app shows the count and groups products as 0, 1, 2 or 3 and more. When the record holds no ingredient information, the count is unknown, not zero.
Nutrition values per 100 g. As recorded: energy, fat, saturated fat, carbohydrates, sugars, fibre, protein, salt.
Position in a comparison group. Invoc's own computation, with its own method and its own weights, explained in sections 2 to 4. It is not the Nutri-Score and not an official measure; the app labels it as Invoc's ranking.

2. How comparison groups are formed

A product is compared only with products that resemble it. Groups are built in steps, and each step must hold at least 5 products to be used; otherwise the next, wider step is tried.

Same category. Every product has a category (for example biscuits, plain yogurts, crisps). The category comes from the Open Food Facts taxonomy; when a record has none, Invoc assigns one with rules based on the product name and its nutrition values, or by hand.
Same grade, same NOVA group, same additive bucket. The first step compares products that share the category, the Nutri-Score grade, the NOVA group and the additive bucket (0, 1, 2, 3 and more). If fewer than 5 products share all four, the additive criterion is dropped; then the NOVA criterion; then only the grade is kept. Products without a grade are compared on NOVA group and additive bucket, then on one of the two.
Wider categories. If no step reaches 5 products, the same steps are tried at the parent category, then at the broad food group of the product.
Large groups. When a group holds more than 50 products, the comparison is narrowed to the products whose index (section 3) lies in the same band, provided that band holds at least 5 products.
Country. Since 27 August 2026, when the product is sold in the shopper's country and at least 5 products of the group are sold there too, the position is computed within that country group: France and Switzerland together, the United States and Canada together. Otherwise it is computed across all countries.
Not ranked. A product is placed in a group only when its record holds a category and its nutrition values. Some product classes are shown but never ranked, because a comparison adds nothing for the shopper: water, eggs, plain milk, salt, wheat flour, ground coffee, black tea, chewing gum, oils, plain butter, pepper and sugars (flavoured waters and oils, margarines, plant-based spreads and sweeteners stay in their groups). Alcohol, baby food and pet food are outside the app. A record whose values contradict each other (saturated fat above total fat; fat, carbohydrates and protein adding up to more than 105 g) or that declares fat without any saturated-fat value receives no index until it is corrected.
One product, several barcodes. The same product sold under several barcodes is shown once in a comparison.

3. How products are ordered inside a group

Inside a group, products are ordered by an index that Invoc computes from six values per 100 g taken from the record: energy, saturated fat, sugars, salt, fibre and protein. The lower the index, the earlier the position. The index itself is never displayed; only the position is.

Direction. Energy, saturated fat, sugars and salt raise the index. Fibre and protein lower it. Total fat is not counted on its own, only its saturated part, as in the official Nutri-Score method.
Weight of each value. The weights are aligned with the Nutri-Score 2023 point scale: each value counts in the same proportion as in the official method. Per gram, salt weighs the most, then saturated fat, then sugars, then energy. Fibre and protein count in the product's favour, up to the same amounts as the official method rewards and no further. Unlike the official method, the index has no ceiling on the values that raise it, and it is not a straight line: the more of a value a product holds, the more each extra gram weighs in the calculation.
The exact formula and its weights are not published. They are Invoc's own work, documented internally with their date and every change, and can be shown to a court or an arbitrator under confidentiality. What is published here is enough to check what the position rests on: which values, in which direction, in which order of weight, and the group rules.
NOVA group and additives are not part of the index. They act as group walls (section 2): a product is ordered only against products of the same NOVA group and the same additive bucket whenever the group allows it.
Missing value. A value absent from the record counts as zero in the index. A product missing a value that raises the index is not penalised for it; a product missing a value that lowers the index gets no credit for it. Fibre is the value most often missing.
Fruit, vegetables and legumes. The official Nutri-Score method rewards the share of fruit, vegetables, legumes and nuts in a product. The index does not count it: that share is missing from most records, because it is not on the nutrition table. Brands can declare it for their products through the brand portal.
Implausible value. A value above what 100 g can physically hold is read as a unit error and divided by 1,000 before use.
Nothing is compared to peers inside the index. The comparison is the order of the group.

4. What the position shown in the app means

The circle on the product page shows the product's position among the products displayed in its comparison strip. The strip holds at most 25 products of the group, ordered by index, with the same product under several barcodes shown once, same-brand entries with the same index shown once, and at most two products per brand (its earliest and its latest placed).
For a product placed beyond the tenth position in a group of more than 20, the circle shows the position within the whole group, and the strip shows the first five products and the product's neighbours.
The same position appears as a badge on the product tile in the scan history and in search results. Positions are recomputed at each data publication; a product's position can change when a record in its group changes.

5. Data sources

Open Food Facts. Product records (names, brands, categories, ingredients, nutrition values, additives, Nutri-Score grade, NOVA group, photos, countries of sale) come from Open Food Facts, the collaborative food product database, and are used under the Open Database License (ODbL). Invoc keeps a copy that is synchronised periodically; the copy can lag behind the live record at world.openfoodfacts.org.
Brands and producers. Since September 2026 a brand can correct and complete the values of its own products, add photos and propose a category through the Invoc brand portal. Values entered by a brand are marked as such and may be shared with Open Food Facts under the same licence.
Invoc's own curation. Open Food Facts is filled in by volunteers and by producers, so records vary in completeness and accuracy. Invoc therefore checks and repairs what it can: names, categories, merges of duplicate barcodes and removals of damaged records decided by hand are recorded with their date, evidence and reasoning in an internal decision ledger, so that a later change to the record can be understood. This is also why brands are invited to correct their own products.

6. Corrections

Anyone may ask Invoc to check a value shown for a product. The procedure, what to send and what Invoc does with it are on the correction page. Invoc checks inputs against the label; it never changes the method for one product.

7. Versions and changes

Version 1.0, 16 September 2026. First publication of this page. It describes the method as it runs on that date.
Version 1.0.1, 16 September 2026. Section 3 states that the fruit, vegetables and legumes share is not counted, and why. No change to the method.
Version 1.1, 17 September 2026. The weights of the index are aligned with the Nutri-Score 2023 point scale: total fat is no longer counted on its own (only its saturated part), sugars and energy weigh less and fibre and protein weigh more than before, in the official proportions, with the same ceilings on the two rewards as the official method. Salt values above 10 g per 100 g are now used as recorded (they were treated as unit errors, which mis-ordered seasonings and stock cubes). A record that declares fat without any saturated-fat value receives no index. Positions recomputed on that date; sections 2 and 3 updated.
Changes to the method before this page existed: 27 August 2026, positions computed within the shopper's country group when possible; 9 and 12 September 2026, the product classes listed in section 2 excluded from ranking and contradictory records left without an index.

Invoc is published by Cross Stream Solutions Sàrl, Lausanne, Switzerland.