Same product, same brand, 5.6x the price — just from buying the smaller bag

Most of what we've written about on this site so far has been about verifiability — whether a label tells you enough to actually compute a price per milligram of the thing you're paying for. Omega-3 and creatine have that problem; vitamin D, vitamin C, calcium, and protein mostly don't, because their Daily Value forces every label onto the same directly-comparable basis.

But once you've solved verifiability, a second and completely different distortion shows up — one that has nothing to do with compound form, brand reputation, or delivery format. It's just: how big is the bag you bought?

The clearest example: BulkSupplements Casein

BulkSupplements sells the exact same micellar casein protein powder — same formula, same brand, same 30g-scoop serving containing 25g of protein — in three container sizes on the same product page. Here's what a gram of protein actually costs at each size:

The 100g bag costs 5.6x more per gram of protein than the 1kg bag — of the identical powder, from the identical brand, at the identical formula. Nothing about the ingredient changed. The only variable is how much plastic you're willing to commit to up front.

This isn't a one-off. The same brand's egg white protein shows a 4.25x spread across the same four pack sizes ($0.0719/g at 1kg vs. $0.3051/g at 100g), and once we pulled more vitamin C pricing, BulkSupplements' plain ascorbic acid powder showed the identical shape: $0.0025/100mg at the 1kg tier vs. $0.0080/100mg at the 250g tier — a 3.2x spread on a compound with zero form ambiguity, where the number on the label is already the final, comparable number.

It's not universal — which is the interesting part

Before this becomes "always buy the biggest bag," one more data point: NOW Sports' Whey Protein Concentrate comes in a 1.5lb and a 5lb size, and the two land at $0.0525/g and $0.0488/g respectively — a difference of about 7%, not 5.6x. Same ingredient category (whey concentrate), same general idea (bigger bag, bulk-style pricing), completely different outcome.

That inconsistency is the real finding. The package-size penalty isn't a fixed law of supplement pricing — it's a per-brand, per-product-line margin decision, and it's invisible on the label and often invisible on the product page too, since a listing at a single pack size gives you no way to know whether you're looking at the brand's "1kg" pricing or its "100g" pricing. You'd need to go find the other pack sizes and do the division yourself to find out — which is exactly the comparison this site exists to do for you.

Why this matters more than it sounds like it should

A naive $/serving or $/container comparison — which is what most price-comparison tools and retailer sort orders actually show you — hides this completely, because the serving size and the per-serving marketing price stay identical across all three BulkSupplements casein tiers. You'd have to already suspect something was off and go compute $/gram yourself to catch it. That's the whole thesis of this project: $/unit-of-active-ingredient isn't a nice-to-have normalization, it's the only view that doesn't quietly mislead you — and package size is turning out to be at least as large a distortion as compound form or brand premium, just less talked about.

Curious what this looks like across all eight categories? Browse the full comparisons →