Casein vs Whey Protein: What the Labels Show

Casein and whey are the two proteins in milk, sold as separate powders and marketed as if they were different in every way. On the label, the two read more alike than the marketing suggests. This guide says how each appears on a label, sorts the protein powders this site publishes by the first ingredient their labels list, and sets the two groups' label figures side by side. Every number is computed from the site's label data each time the site is built, and each count names what it is out of. Nothing here says what either protein does; these are label and price figures.

How each appears on a label

Milk protein is roughly four parts casein to one part whey. Separated, each gets its own ingredient name. Casein is listed as "micellar casein" or, less often, as a caseinate ("calcium caseinate", "sodium caseinate"). Whey is listed as whey protein isolate or whey protein concentrate; the whey isolate vs whey concentrate guide sorts those two.

"Milk protein isolate" and "milk protein concentrate" are a third thing: both proteins in one ingredient, in the proportion milk has them. A powder that leads with one of those is in neither group below, and so is a powder that lists casein and whey as separate ingredients with whey first; it counts as whey-first, because the first ingredient is the one present in the largest amount (21 CFR 101.4(a)).

How this guide sorts the shelf

Labels this can sort: 86 of 92 protein powders published here have an ingredient list read in its printed order.
Casein first: 8 of 86 open with micellar casein or a caseinate. Whey first: 46 of 86 open with a whey ingredient, mass gainers left aside.
The front of the tub: 8 of 8 casein-first powders say "casein" in their product name, and 1 of 86 sortable powders say "casein" in the name without listing casein first.

A casein powder, then, says so on the front. The whey guide shows that the same cannot be said of isolate.

What the labels show

Each figure below is the median across the labels in that group that print it, and each names how many labels it covers. The casein group is small, so its medians rest on fewer labels than the whey group's.

Protein as a share of serving weight: casein-first 71% across the 8 of 8 that print protein and serving weight; whey-first 76% across the 46 of 46.
Protein per serving: casein-first 25 g across 8 of 8; whey-first 25 g across 46 of 46.
Total carbohydrate per serving: casein-first 3 g across 8 of 8; whey-first 3 g across 46 of 46.
Total sugars per serving: casein-first 1 g across 7 of 8; whey-first 1 g across 41 of 46.
Fat per serving: casein-first 0.8 g across 8 of 8; whey-first 1.5 g across 45 of 46.

Protein per serving is the figure to notice: a scoop of either is built to deliver about the same protein, and the serving weight, flavouring and sweetener do the rest. A Nutrition Facts panel has no lactose line; whatever lactose either powder holds sits in its carbohydrate and sugars rows.

What a gram of protein costs

Cost per gram of protein is the brand's own store price divided by the protein the package holds as its label states it, the figure every protein ranking here uses (the cost per gram guide works through it).

Casein-first: median $0.072 per gram of protein across the 7 of 8 with a brand-store price.
Whey-first: median $0.081 across the 38 of 46 with one.

Per gram of protein, the casein-first median costs 11% less. A powder with no cost figure has no current brand-store price on record, or a package the price cannot be matched to, and is left out rather than estimated.

What this comparison cannot settle

Anything about speed or timing. Casein is sold on how it behaves after it is drunk. A label prints what is in the scoop, not what happens next, and this guide stops where the label does.
The mix inside a blend. A powder listing casein first and whey second says only that there is at least as much casein; the amounts are not printed (the proprietary blends guide covers the gap).

The casein ranking and the whey protein ranking list the products behind these figures by name, scored on the method in how we rate.

Data study: What a gram of protein costs across 86 protein powders: the same shelf in aggregate, with a CSV. All data studies.