A fair question to ask any price comparison site is: where does the data actually come from? Here's an honest answer for WheyWise.
Weekly automated price tracking
A script runs once a week and visits the product pages of each tracked retailer. It reads the current price, checks whether the item is in stock, and stores both in a database. That database is what powers the comparison table you see on this site.
The price check runs in the early hours UK time, so prices shown here reflect roughly the previous night's data. If a retailer changes a price in the afternoon, it won't show here until the following morning.
Price per 100g normalisation
Raw prices are almost useless for comparison. A £30 bag of 1kg and a £50 bag of 2.5kg can't be compared without doing maths first. WheyWise converts every price to a cost per 100g, which is the only number that matters for comparing value.
The formula is simple: (price ÷ weight_in_grams) × 100. Where a product has an active discount code, the post-code price per 100g is calculated and shown alongside the original.
Which retailers are tracked
Currently the main UK retailers: MyProtein, Bulk, Optimum Nutrition via Amazon UK and Holland & Barrett, Protein Works, PhD Nutrition, and a few others. The list grows over time — usually when someone messages me asking why a particular retailer isn't included.
Discount codes
Retailers frequently run discount codes — especially MyProtein and Bulk. Where I'm aware of an active code, it's stored alongside the product and used to calculate an effective price. The code is shown next to the price and can be copied with one click.
I don't have a systematic way of discovering new codes automatically yet — they're added manually when I spot them or when someone sends them in. If you know of a code that's not showing, let me know.
When prices differ from what you see at checkout
This happens occasionally. Reasons include: the price changed after the last update ran, the retailer is showing a different price based on your account or location, or our fetch hit a cached page. Always check the final price at checkout before buying.
If a price is consistently wrong, that's likely a tracking issue. Report it via the contact page and I'll fix it.
What isn't tracked
Protein bars, ready-to-drink shakes, creatine, BCAAs, and other supplements are out of scope for now — this is specifically protein powder. Within that, flavour availability varies; not every flavour of every product is tracked, just the most common ones.
To see exactly what is tracked and compare live prices, head to the price comparison table. For a breakdown of which products offer the best value, see cheapest protein per gram in the UK.
