Mass gainers comparison
BSN True-Mass vs Optimum Nutrition Serious Mass
ON Serious Mass scores higher on our standard, 39/100 to 37/100. It earns more points for ingredient simplicity (mixed natural and artificial vs artificial flavors or sweeteners). We could not verify a current price for ON Serious Mass, so we can't compare cost.
Both are scored out of 100 against our published standard: protein density, third-party testing, label transparency, sugar, ingredient simplicity and verified label data. Every number below is from the manufacturer's label; last checked 2026-10-14.
Optimum Nutrition
Serious Mass
Side by side
Per serving, from each label. Bold marks the better score, protein density, sugar and cost where the two differ. How we score
| Compared | BSN True-Mass | ON Serious Mass |
|---|---|---|
| Our score | 37/100 | 39/100 (better) |
| Protein density | 6 / 3028% of each scoop is protein | 6 / 3015% of each scoop is protein |
| Third-party testing | 0 / 25No verified independent testing program | 0 / 25No verified independent testing program |
| Label transparency | 20 / 20Fully disclosed formula, no amino spiking | 20 / 20Fully disclosed formula, no amino spiking |
| Sugar | 2 / 1015 g sugar per serving | 2 / 1029 g sugar per serving |
| Ingredient simplicity | 4 / 10Artificial flavors or sweeteners | 6 / 10 (better)Mix of natural and artificial flavors or sweeteners |
| Verified label data | 5 / 57 of 7 label values verified | 5 / 57 of 7 label values verified |
| Type | Mass Gainer | Mass Gainer |
| Protein per serving | 47 g | 50 g |
| Serving size | About 3 rounded scoops (165 g) | 340 g (About 2 Scoops) |
| Protein by weight | 28% (better) | 15% |
| Sugar | 15 g (better) | 29 g |
| Calories | 690 | 1260 |
| Cost per 25 g protein | $2.59 | Not verified |
| Price per serving | $4.86 | Not verified |
| Third-party certifications | None found | None found |
| Sweeteners | Sucralose | Acesulfame Potassium, Sucralose |
| Allergens | Milk, Soy | Milk, Soy |
| Proprietary blend | No | No |
| Added free amino acids (amino spiking) | No | No |
| Last checked | 2026-10-14 | 2026-10-13 |
Which to choose
Only the differences in our records. A value we couldn't verify never counts as a difference.
Choose BSN True-Mass if…
- You want more of each scoop to be protein (28% vs 15% by weight).
- You want less sugar (15 g vs 29 g per serving).
Choose ON Serious Mass if…
- You want more protein per serving (50 g vs 47 g).
- You want more calories per serving (1260 vs 690).
The two powders
Good to know
Labels and prices change, so check the package before buying, especially if you have allergies. If you are pregnant, nursing, buying for a child or managing a health condition, ask your doctor before adding a supplement.