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A protein tub is one of the most confidently labelled products in any supplement aisle and one of the hardest to compare. The front says 25 g of protein. The scoop says 32 g. The tub says 2 kg. The price says $89. None of those numbers, on its own, tells you whether this tub is better value than the one beside it.
This article is about reading the tub. It covers the main protein types sold as powders — whey concentrate, whey isolate, whey hydrolysate, casein, soy, pea, rice and blends — and the handful of label numbers that let you compare them like for like. It does not tell you how much protein to eat, and it does not claim that any powder does anything for your health. If you want the background on protein and ageing, Protein and Muscle After Forty covers that; this piece starts at the shelf. If supplement labels in general are new to you, How to Read a Supplement Label is the place to begin.
The one number that matters: protein per serve, not scoop size
Every protein tub carries a Supplement Facts or Nutrition Information panel, and the first line worth finding is serving size in grams, followed by protein per serving in grams. Divide the second by the first and you have the figure that lets you compare any two tubs: the protein percentage by weight.
A tub that gives 25 g of protein in a 30 g scoop is roughly 83 per cent protein. A tub that gives 25 g of protein in a 40 g scoop is about 63 per cent protein. Both say “25 g protein per serve” on the front, and both are telling the truth. The second one has more of something else in the scoop — carbohydrate, fat, flavouring, thickener, sweetener, or simply moisture — and you are paying for that something else at protein prices.
Scoop size is set by the manufacturer and varies from about 25 g to over 45 g. It is a serving convention, not a quality signal, and it is the single easiest way for two products to look identical while being quite different.
Whey: concentrate, isolate and hydrolysate
Whey is the liquid fraction of milk left after cheese-making. Dried and filtered, it becomes whey protein powder, and the three names on the shelf describe how far that filtering went.
Whey protein concentrate (WPC)
The least processed of the three. Concentrates are typically labelled between about 70 and 80 per cent protein by weight, though the range on sale is wider — some products labelled “concentrate” sit closer to 35 per cent, which is why the arithmetic above matters more than the word on the tub. The remainder is mostly lactose (milk sugar), some fat and minerals. It is usually the cheapest whey per gram of protein.
Whey protein isolate (WPI)
Further filtered to remove most of the lactose and fat. Isolates are usually labelled at 90 per cent protein by weight or above. The label will typically show carbohydrate under about 1 g per serve and fat well under 1 g. Isolate costs more per tub than concentrate; whether it costs more per gram of protein depends entirely on the two tubs in front of you, and the section on cost below shows how to check.
Whey protein hydrolysate (WPH)
Isolate or concentrate that has been pre-treated with enzymes to break some of the protein chains into shorter fragments. The label is otherwise similar to the source material. Hydrolysates are the most expensive form and taste noticeably more bitter, which is why they are often blended rather than sold pure. The Supplement Facts panel does not usually state the degree of hydrolysis; if a product makes a point of it, the figure will be in the marketing copy, not the panel.
What to read on a whey label: protein per serve and serving size; carbohydrate per serve (a proxy for lactose in whey products); the ingredient list, which should begin with the whey type the front of the tub advertises. If “whey protein concentrate” appears first in the ingredients of a tub marketed as isolate, the product is a blend and the front label is doing a lot of work.
Casein
Casein is the other milk protein — the curd rather than the whey, making up roughly 80 per cent of the protein in cow’s milk. As a powder it is sold as micellar casein (the native structure) or calcium caseinate (chemically extracted, more soluble, cheaper).
On the label, casein powders look much like whey isolates: typically 75 to 85 per cent protein by weight, low in carbohydrate and fat. The practical difference you will notice is texture — casein thickens dramatically in liquid, which is why it is often marketed for puddings and overnight mixes. Products labelled simply “milk protein” or “milk protein concentrate” are usually the natural ratio of casein to whey, about 80:20, and are priced between the two.
Soy, pea, rice and other plant proteins
Plant protein powders are extracted from legumes or grains, and the label differences from dairy are worth knowing before you compare.
Soy protein isolate
Typically labelled at about 90 per cent protein by weight, comparable to whey isolate on the panel. Soy is a complete protein — it contains all nine essential amino acids in useful proportions — which is why it has historically been the plant reference point. The ingredient list will say whether the soy is non-GMO or organic, which matters to some buyers and has no bearing on the protein figure.
Pea protein
Usually labelled between 75 and 85 per cent protein by weight. Pea protein is relatively low in the amino acid methionine, which is why many pea products are blended with rice protein, which is relatively low in lysine; together the two cover each other’s gap. A single-source pea powder is not “incomplete” in any dramatic sense, but the amino acid panel, where printed, will show the pattern.
Rice protein
Brown rice protein is typically labelled at about 80 per cent protein by weight, and is most often seen as the partner in a pea-rice blend rather than on its own.
Hemp, pumpkin seed and other single-seed powders
These sit lower on the protein percentage — hemp is commonly around 50 per cent protein by weight, with the balance mostly fibre and fat. They are sold as food-first products rather than protein-first ones, and comparing them on protein per dollar against a whey isolate will always make them look expensive. That is not a flaw in the product; it is a mismatch in the comparison.
What to read on a plant protein label: the protein percentage (the same arithmetic); whether it is a single source or a blend; whether an amino acid profile is printed; the fibre figure, which is often substantial; and the sodium figure, which is often higher than in dairy powders because of the extraction process.
The amino acid panel, if there is one
Some tubs print a full amino acid profile per serve. It is optional on most labels and its absence does not mean anything is being hidden. When it is present, the figures most people look for are the nine essential amino acids and, within them, the three branched-chain amino acids: leucine, isoleucine and valine. Whey contains more leucine per gram than casein or soy — the U.S. National Institutes of Health Office of Dietary Supplements notes this in its fact sheet on dietary supplements for exercise — and manufacturers know it, which is why some products add free leucine or a “BCAA blend” to a base powder.
A label-reading point: when free amino acids are added, some panels count them toward the protein figure and some do not. Regulations differ by country. If the protein per serve looks unusually high for the stated source, check whether the ingredient list includes added glycine, taurine, creatine or free-form amino acids — a practice sometimes called amino spiking. Added glycine and taurine are cheap, they register as nitrogen in the standard protein test, and they are not the same thing as intact protein.
Lactose, sweeteners and “other ingredients”
Below the protein line, the panel and the ingredient list tell you what else is in the scoop.
- Carbohydrate and sugars. In whey concentrate this is mostly lactose. A concentrate at 3–5 g carbohydrate per serve is normal; an isolate should be under 1 g. Plant powders vary with the fibre content.
- Sweeteners. Sucralose, acesulfame potassium and stevia are the common ones. “Unflavoured” or “natural” tubs often still contain a sweetener; the ingredient list settles it.
- Thickeners and emulsifiers. Xanthan gum, guar gum, soy or sunflower lecithin. These are what make a shake feel like a shake. They are also non-protein weight in the scoop.
- Added enzymes. Lactase, protease and similar are increasingly listed. Their presence is a formulation choice, not a quality grade.
- Allergen statement. Dairy powders declare milk; many are also made on lines that handle soy, egg, nuts or gluten and say so. Read it if it matters to you.
The comparison that actually works: cost per 100 g of protein
Price per tub is meaningless without the two numbers above, so here is the arithmetic that turns any two tubs into a fair comparison.
- Find the tub’s total weight in grams and its price.
- Find protein per serve and serving size, and divide to get the protein fraction (for example, 25 ÷ 30 = 0.83).
- Multiply the tub weight by the protein fraction to get total protein in the tub (for example, 2,000 g × 0.83 = 1,660 g of protein).
- Divide the price by that figure and multiply by 100 to get the cost per 100 g of protein (for example, $89 ÷ 1,660 × 100 = $5.36 per 100 g of protein).
A worked comparison, with illustrative prices rather than any retailer’s current ones:
| Tub | Weight | Price | Protein/serve ÷ serve size | Protein in tub | Cost per 100 g protein |
|---|---|---|---|---|---|
| Whey concentrate | 2,000 g | $69 | 24 g ÷ 32 g = 0.75 | 1,500 g | $4.60 |
| Whey isolate | 1,000 g | $59 | 27 g ÷ 30 g = 0.90 | 900 g | $6.56 |
| Pea–rice blend | 1,000 g | $45 | 21 g ÷ 28 g = 0.75 | 750 g | $6.00 |
| “Lean” flavoured blend | 1,500 g | $79 | 20 g ÷ 40 g = 0.50 | 750 g | $10.53 |
The last row is the point of the exercise. It is the tub with the biggest weight and a mid-range price, and it is the most expensive protein in the table by a wide margin, because half of every scoop is something other than protein. Nothing on its front label is false.
Reading the rest of the tub
- Servings per container. Divide tub weight by serving size and check the manufacturer’s number agrees. A tub claiming 66 serves of 30 g weighs 1,980 g, not 2,000 g; the small discrepancy is rounding, a large one is worth noticing.
- Batch number and best-before date. Dry powders keep well but not indefinitely, and an opened tub absorbs moisture. A batch number is also what a third-party tester quotes when a product is checked.
- Third-party seals. Informed Sport, NSF Certified for Sport and similar programmes test batches for banned substances and label accuracy. They do not test whether the product does anything. What supplement seals actually certify covers each programme.
- Country of manufacture and importer. On products bought internationally, this tells you whose labelling rules the panel follows — which is why the same brand’s tub can show different numbers in different markets.
- Storage and scoop. Trivial, but a tub that says “scoop inside” and arrives without one has just lost its serving size.
A short checklist before you buy
- Compute protein per serve divided by serving size. Anything under about 0.70 is carrying a lot of non-protein weight.
- Check the ingredient list begins with the protein type on the front of the tub.
- Check for added free amino acids that may be inflating the protein figure.
- Compute cost per 100 g of protein for every tub you are comparing, using the tub in front of you, not the marketing.
- Read the allergen statement and the sweetener if either matters to you.
- Check the best-before date is comfortably beyond the time it will take you to finish the tub.
Sources
- National Institutes of Health, Office of Dietary Supplements, Dietary Supplements for Exercise and Athletic Performance — Fact Sheet for Health Professionals, for the protein-source and leucine points and for intake ranges reported in the literature.
- U.S. Food and Drug Administration, Dietary Supplement Labeling Guide, for what a Supplement Facts panel must show.
- Protein percentages by type are the typical labelled ranges observed across products on sale; the arithmetic in this article lets you check any specific tub yourself rather than rely on a range.
This article is a guide to reading packaging and comparing products. It is general information only and is not medical advice. It makes no claim that protein powder benefits any condition, it recommends no dose, and it does not diagnose, treat, or cure any condition. Speak with a qualified healthcare professional before starting any supplement.