How is cost per 30g of protein calculated?

Pack price divided by the grams of protein in the pack, multiplied by 30. Grams of protein in the pack is the pack weight multiplied by the protein per 100g on the label.

How are ready to drink products handled?

For ready to drink products the pack is a number of bottles rather than a weight, so the protein per bottle is multiplied by the bottle count to give the protein in the pack.

Where do the prices come from and how current are they?

Every price is an observation recorded against the retailer page it came from, with the date it was taken. Each reading is stored as a new row rather than overwriting the last, and the date checked is shown beside every price.

Does commission affect the ranking?

No. Some outbound links earn a commission, but that has no effect on a product's position, its figures, or whether it appears at all. No brand can pay to enter the index, to move up it, or to be removed from it.

Methodology

How we rank

One number decides every position in the index. Here is exactly how it is worked out, where the figures come from, and what does not influence them.

The calculation

pack price ÷ grams of protein in the pack × 30

Grams of protein in the pack is the pack weight multiplied by the protein per 100g on the label. For ready to drink products, where the pack is a number of bottles rather than a weight, we use the protein per bottle multiplied by the bottle count.

Where the numbers come from

Prices are observations, not promises. Each one is recorded against the retailer page it came from, with the date it was taken, and it is stored as a new reading rather than overwriting the last one. That means the index has a price history behind it rather than a single snapshot. The figures shown on the site are always the most recent reading for each product, and every price on the site carries the date it was checked beside it. Nutrition figures are taken from the manufacturer's own label. Where a retailer does not attribute a price to a specific pack size on its own page, the reading is marked indicative with an amber dot rather than quietly presented as verified.

Commission does not affect ranking

Some outbound links to retailers earn Protein Index a commission if you buy through them. That commission has no effect whatsoever on a product's position, its score, or whether it appears in the index at all. Ranking is produced by the calculation above and nothing else, and the same calculation is applied identically to every product, including those that pay us nothing. Every commercial link is labelled "Ad" next to the link itself, opens in a new tab, and is marked as sponsored so search engines treat it correctly. No brand can pay to enter the index, to move up it, or to be removed from it.

Products tracked

£0.54

Best in the index

6.1x

Spread

Prices last checked 16 Sept 2026

Common questions

How is cost per 30g of protein calculated?: Pack price divided by the grams of protein in the pack, multiplied by 30. Grams of protein in the pack is the pack weight multiplied by the protein per 100g on the label.
How are ready to drink products handled?: For ready to drink products the pack is a number of bottles rather than a weight, so the protein per bottle is multiplied by the bottle count to give the protein in the pack.
Where do the prices come from and how current are they?: Every price is an observation recorded against the retailer page it came from, with the date it was taken. Each reading is stored as a new row rather than overwriting the last, and the date checked is shown beside every price.
Does commission affect the ranking?: No. Some outbound links earn a commission, but that has no effect on a product's position, its figures, or whether it appears at all. No brand can pay to enter the index, to move up it, or to be removed from it.

Privacy

We collect an email address only if you choose to give us one for the weekly newsletter, and we use it for nothing else. You can ask to be removed at any time and the record is marked unsubscribed immediately. We do not sell or share subscriber data.

Contact

Spotted a price that looks wrong, a label figure that does not match, or a product missing from the index? Tell us and we will recheck it. Corrections are logged as a new price reading with the date, so the change is visible rather than silent.

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