Glossary

A

Affiliate link

A hyperlink that includes a special tracking tag (e.g., tag=unitcheck01-20) added by the retailer's affiliate program. When you click an affiliate link and make a purchase, the retailer knows to credit the commission to UnitCheck's account. The price you pay is identical to a direct link.

B

Best Value score

A composite ranking metric that combines unit price with quality signals (review count and rating). It is one sort option on category pages; you can always choose to sort by unit price alone instead. See the /methodology page for the complete formula.

C

Confidence (extraction confidence)

A numerical score (0.0 to 1.0) assigned by our LLM when it extracts nutrition data from a product listing. Higher confidence means the AI was more certain about the values (e.g., protein per serving). If confidence is very low (below 0.80), the product may show a "Low confidence — verify on Amazon" badge and may be excluded from rankings until human review confirms the data.

G

$/g powder (price per gram of powder)

The unit price calculated by dividing the product price by the total weight in grams. Example: $39.99 ÷ 2,000g = $0.02 per gram of powder. This is a commonly used metric but does not account for protein density—a powder with 50% protein content looks identical in price per gram to one with 20% protein content. See $/g protein for a more useful metric.

$/g protein (price per gram of protein)

The unit price calculated by dividing the product price by the total grams of actual protein in the container. This is UnitCheck's primary ranking metric for protein powders. Example: $39.99 ÷ 1,900g protein = $0.021 per gram of protein. This metric normalizes for protein density and is what informed buyers actually care about. See the /methodology page for the full calculation.

$/serving (price per serving)

The unit price calculated by dividing the product price by the number of servings per container. Example: $39.99 ÷ 76 servings = $0.53 per serving. This is intuitive for casual buyers but does not normalize for protein content, so it can be misleading when comparing products with different protein densities.

Grass-fed

A dietary claim indicating that the dairy cows producing the whey protein were fed primarily grass pasture rather than grain-based feed. Grass-fed products typically cost more per unit but are preferred by some consumers for perceived nutritional or environmental reasons.

L

Last synced (or "Last checked")

The timestamp showing when we most recently fetched price and availability data from the retailer. Example: "Checked 3 hours ago." Always verify the current price on Amazon before purchasing, as prices can change at any time. If data is older than 72 hours, a "stale data" warning may appear.

P

Price per 100g protein

An alternative unit-price display for readers who prefer larger numbers. Calculated as: 100 × ($/g protein). Example: if $/g protein is $0.021, then price per 100g protein is $2.10. See the /methodology page for the calculation.

Prime eligible

A label indicating that the product qualifies for Amazon Prime free shipping and fast delivery. Prime-eligible products receive a small bonus (5%) in the Best Value ranking because of added convenience, but this does not override meaningful unit-price differences.

Product detail page

A dedicated page showing all available information about a single product: full title, brand, price, nutrition facts, reviews, a link to the Amazon listing, and the unit-price metrics in all available units.

Q

Quality flag

A label applied to a product when it exhibits suspicious or low-quality signals. Examples include "Low review count — verify seller," "Price outlier — verify before buying," "Below-average rating," or "Recently listed." Flagged products may be hidden from default category views but are still accessible if you adjust filters. See the /methodology page for all flag types.

S

Serving (servings per container)

The number of single servings in one container, as stated on the product label. Example: a 5-pound tub with 76 servings means each serving is approximately 1.05 ounces. Required to calculate $/serving and $/g protein.

Sub-category

A filter within a category that narrows products by type. For protein powders, sub-categories include "Whey Isolate," "Whey Concentrate," "Casein," "Plant-Based," "Collagen," and "Blends." Each sub-category generates its own leaderboard page.

U

Unit price

The cost of a product divided by a standard unit of measure (grams, servings, ounces, etc.). Unit prices allow fair comparison between different package sizes. UnitCheck displays multiple unit-price metrics for each product so you can choose the one that matters most to you.

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Last updated: April 27, 2026

For detailed information on how we calculate unit prices and apply quality filters, see the Methodology page.