Head to head · Protein Powder
Optimum Nutrition Gold Standard 100% Casein vs Optimum Nutrition Gold Standard 100% Whey
Gold Standard 100% Whey scores higher overall (8.7 vs 8.1 out of 10), mainly on efficacy, quality & purity and experience.
Updated September 2026 from our full reviews · How we score
A slow-digesting micellar casein with 24 g of protein per scoop for bedtime or long gaps between meals; thick, filling and fairly priced.
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The benchmark whey blend: 24 g of protein per 120-calorie scoop, Informed Choice certified, and a flavor lineup few rivals can match.
We may earn a commission when you buy through these links — it never affects our scores. How we make money
We may earn a commission when you buy through these links — it never affects our scores. How we make money
The short answer
Choose Gold Standard 100% Casein if…
- A slow-digesting shake before bed
- Staying full between meals
- Thick shakes and protein puddings
Choose Gold Standard 100% Whey if…
- First-time protein powder buyers
- Everyday post-workout shakes
- Drug-tested athletes who want a certified product
- People who like lots of flavor choice
- You care most about efficacy, quality & purity, experience
Side by side
| Gold Standard 100% Casein | Gold Standard 100% Whey | |
|---|---|---|
| Our score | 8.1 / 10 | 8.7 / 10 |
| Efficacy (30%) | 8.3 | 8.8 |
| Quality & Purity (25%) | 7.4 | 9.0 |
| Value (20%) | 8.6 | 8.3 |
| Experience (15%) | 8.5 | 9.0 |
| Transparency (10%) | 7.8 | 8.0 |
| Form | Powder | Powder |
| Serving | 1 scoop (34 g)53 servings per container | 1 scoop (31 g)74 servings per container |
| Testing & certifications | None verified | Informed Choice |
| Dietary | Gluten-free | Gluten-free |
| Key ingredients |
|
|
| Flavors | 4 (Chocolate Supreme, Creamy Vanilla, Chocolate Peanut Butter…) | 8 (Double Rich Chocolate, Extreme Milk Chocolate, Vanilla Ice Cream…) |
| Creator video reviews | 3 | 5 |
Pros and cons
Gold Standard 100% Casein
- 24 g of micellar casein protein per 120-calorie scoop
- Adds 500 mg of calcium and 100% of the Daily Value for zinc
- About $1.40 per serving, good value for casein
- 4.6 stars from more than 9,000 buyer ratings, with many saying it keeps them full
- Not listed among ON's Informed Choice-certified products
- Sweetened with both acesulfame potassium and sucralose, plus artificial flavor
- Thick texture and mixability get mixed reviews
- One scoop is below the 30 to 40 g used in most pre-sleep protein studies
Gold Standard 100% Whey
- 24 g of protein in a 120-calorie, 31 g scoop (about 77% protein by weight)
- Informed Choice certified and regularly tested for banned substances
- More than 20 flavors on the brand's US store, with consistently strong feedback on taste and mixability
- Fully disclosed ingredient list with no proprietary blend
- Widely available on Amazon, TikTok Shop and at major retailers
- Sweetened with acesulfame potassium and uses artificial flavors
- Contains whey concentrate, and a share of buyers report digestive discomfort
- No longer cheap: about $1.39 per serving at typical retail prices for the 5 lb tub, and the brand-site list price is higher
- Servings per tub vary by flavor (roughly 68 to 75 in 5 lb-class tubs), which complicates price comparisons
Our verdicts
Gold Standard 100% Casein
Gold Standard 100% Casein is a dependable, well-priced micellar casein for nighttime or between-meal protein, with good flavor and a filling texture. It lacks the named third-party certification of ON's whey and uses artificial sweeteners, but for most people who want a slow-digesting shake it does the job at a fair price.
Full review
Gold Standard 100% Whey
Gold Standard 100% Whey remains a default recommendation for good reason: a lean 24 g protein dose, banned-substance certification, and taste and mixability endorsed across about 100,000 buyer ratings. It is no longer a bargain, and the concentrate and artificial sweetener will not suit everyone, but few powders balance quality, variety and availability this well.
Full review
What creators say
Questions people ask
Is Gold Standard 100% Casein better than Gold Standard 100% Whey?
Are Gold Standard 100% Casein and Gold Standard 100% Whey third-party tested?
Who should choose Gold Standard 100% Casein over Gold Standard 100% Whey?
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