Whey Protein Price Per Gram Explained

You see two whey products: £25 for 1kg and £50 for 2.5kg. Which is cheaper? Seems simple, but there's missing information. That £25 tub might have 70% protein, while the £50 bag has 82%.

Why price per kilo is misleading

Say you buy whey A for £25 per kilo with 70% protein. You're paying £25 for 700g of protein. That's £0.036 per gram of protein.

Whey B costs £32 per kilo but has 90% protein (isolate). You're paying £32 for 900g of protein. That's £0.036 per gram of protein.

The more expensive product can actually be cheaper. And you won't see that from the kilo price alone.

The formula

Price per gram protein = (price ÷ weight in grams) ÷ (protein percentage ÷ 100)

Or simpler: divide the kilo price by the protein percentage, multiply by 100.

A product at £21/kg with 80% protein: (21 ÷ 80) × 100 = £0.026 per gram protein.

Concentrate vs isolate: what's actually cheaper?

The cheapest products are almost always concentrates (70-80% protein). Isolates run 85-92% protein but cost more per kilo. Does the higher protein content compensate for the higher price?

Usually: no. Concentrates win on price per gram. But the gap is often small. If you're lactose intolerant or cutting calories hard, isolate might be worth the premium.

Tip: bigger bags aren't always cheaper

Common mistake. A 5kg bag looks better value, but always check price per gram protein. Some brands barely increase the kilo price for smaller sizes. Others give significant bulk discounts.

At Bulk for example: 1kg Pure Whey costs £22.99/kg, 2.5kg costs £20.00/kg. That's 13% cheaper per kilo. But at other brands the difference might be 2-3%.

Practical tip: use our ranking

On our whey ranking page you can sort by price per gram protein automatically. No manual calculations needed. We update prices daily.

And yes, the cheapest whey isn't necessarily the best. Taste, mixability and digestibility matter too. But when two products are equally good, you want to know which is truly better value.

Sources

Jäger R. et al. "International Society of Sports Nutrition Position Stand: protein and exercise." J Int Soc Sports Nutr. 2017. PubMed