The Best Casein Protein Powder
The best casein protein powder is Rule 1 Casein, at $1.14 for 25 g of protein (one scoop), the least of the 7 caseins on a testing list we compared. Want the best-known brand? Optimum Nutrition Gold Standard is on a list too, at $1.48.
Our pick for: Most people
- A scoop
- $1.1425 g protein
- A tub
- $64.9957 scoops, on Amazon
- Testing list
- Informed ChoiceTests for banned substances
Why we pick it It costs the least for each gram of protein among the caseins on a testing list, and each scoop gives 25 g of micellar casein. Informed Choice buys it off the shelf each month and tests it for substances banned in sport.
What you give up Informed Choice checks for banned substances, not that a scoop holds the protein on the label. If you are drug tested, pick a powder tested batch by batch, such as NOW.
The best casein for your needs
Rule 1 suits most people. If you want the best-known brand, an unflavored powder or batch-by-batch testing, pick one of these.
The best-known brand: Optimum Nutrition Gold Standard Casein
Optimum Nutrition Gold Standard Casein gives 24 g of protein a scoop and is on Informed Choice too. It costs about 30% more for the same protein.
Optimum Nutrition Gold Standard Casein
$1.48 for 25 g protein · $78.00 a 4 lb tub (about 55 scoops)
Unflavored, or for drug-tested athletes: NOW Sports Micellar Casein
NOW Sports Micellar Casein has no flavor or sweetener, so it stirs into oatmeal or yogurt. It is on Informed Sport, which tests products batch by batch for substances banned in sport. A scoop is smaller: 19 g of protein.
NOW Sports Micellar Casein
$1.42 for 25 g protein · $36.75 a 1.8 lb bag (34 scoops)
7 casein powders on a testing list, compared
Cheapest for 25 g of protein first, at Amazon prices checked November 6, 2026. We price 25 g so a 19 g scoop and a 25 g scoop compare fairly.
| Casein | Cost for 25 g protein | Why it is or is not the pick |
|---|---|---|
| Rule 1 Casein25 g in a scoop · Vanilla creme · Informed Choice | $1.14 | Our pick: least for the protein |
| Dymatize Elite Casein25 g in a 33 g scoop · Smooth vanilla · Informed Choice | $1.27 | About 12% more than the pick |
| NOW Sports Micellar Casein19 g in a 24 g scoop · Unflavored · Informed Sport | $1.42 | Unflavored; Informed Sport |
| Optimum Nutrition Gold Standard Casein24 g in a 33 g scoop · Chocolate supreme · Informed Choice | $1.48 | The best-known brand |
| Ascent Micellar Casein25 g in a 32 g scoop · Vanilla bean · Informed Sport | $1.61 | Smaller 2 lb tub; Informed Sport |
| Kaged Premium Casein25 g in a scoop · Vanilla · Informed Sport | $1.61 | Smaller tub; Informed Sport |
| Klean Athlete Klean Casein24 g in a 31 g scoop · Vanilla custard · NSF Certified for Sport | $3.57 | NSF Certified for Sport; costs the most |
Questions people ask
Is casein better than whey?
Neither is better for your daily protein total; both are milk proteins. Casein digests slowly and makes a thick shake, so people take it before bed or between meals. Whey digests fast and usually costs less. See the best protein powder.
What does the testing list check?
Informed Choice, Informed Sport and NSF Certified for Sport test for substances banned in sport. Informed Sport tests every batch; Informed Choice buys products off the shelf each month. NSF Certified for Sport also checks that the label is right. Athletes who are drug tested should pick Informed Sport or NSF Certified for Sport.
What about Naked, Transparent Labs or Muscle Feast?
Transparent Labs Grass-Fed Casein is on Informed Choice, but it is sold on Transparent Labs’ own site, so we can’t price it here. Naked Casein’s Amazon listing says “NSF Certified,” but we did not find it on NSF Certified for Sport. Muscle Feast and Nutricost are on none of the lists we check.
What is micellar casein?
It is casein as it occurs in milk, in small clusters that digest slowly. All 7 powders here are micellar casein.
How we picked
We looked at the casein powders ChatGPT and the big review sites name, kept the ones on Informed Choice, Informed Sport or NSF Certified for Sport that Amazon sells, read their labels, and priced each on Amazon for 25 g of protein. Or see the protein guide.
Sources
- Testing lists: Informed Choice certified products (Rule 1 Casein Protein; ON Gold Standard 100% Casein (USA); Dymatize Elite Casein (USA)), copy of October 27, 2026; Informed Sport (NOW Sports Instantized Micellar Casein; Ascent 100% Casein; Kaged Casein); NSF Certified for Sport (Klean Casein Natural Vanilla Custard), copy of October 1, 2026.
- NIH Dietary Supplement Label Database: ON Gold Standard 100% Casein 4 lb (33 g scoop, 55 servings), label 308427; NOW Sports Micellar Casein, label 314487; Ascent Micellar Casein Vanilla Bean, label 182005; Klean Casein Vanilla Custard, label 293258. Rule 1, Dymatize and Kaged: protein and servings from their Amazon listings.