Comparison methodology
How SupplementScout compares supplement prices
We compare offers mapped to the same reviewed product or variant. We prefer a known delivered total over a cheaper-looking product price with unknown delivery, and we show value calculations only when the fields needed for that calculation have been verified.
Delivered price
A known delivered total is the product price plus the known delivery charge. Free delivery is counted as £0 only when the retailer data explicitly records it. If delivery is missing, the total stays unknown: we do not treat missing delivery as free.
Product and variant identity
Retailer listings are mapped to SupplementScout's canonical products and variants. Pack sizes, flavours and formulations stay separate when they represent different buying choices. We do not combine listings just because their names look similar.
How results are ordered
Within one product, eligible offers with known delivery are ordered by delivered total. An offer with unknown delivery cannot outrank an offer with a complete delivered price. On category comparison pages, products with broader current retailer coverage appear first before offer count and verified data completeness.
This is a price-and-coverage order, not a ranking of effectiveness, formulation quality, safety or suitability.
Verified value metrics
Price per kilogram, litre, capsule, tablet or serving is shown only when the package or serving evidence required by that metric is valid. Nutrition-based calculations, such as cost per 25 g of protein or per 5 g of creatine, additionally require verified nutrition and unit-pricing evidence. The known delivered total is used, not only the shelf price.
If any required field is missing or unverified, the metric is hidden or marked not yet verified rather than estimated from a name, pack image or retailer description.
Price history
Product charts use valid recorded delivered-price observations linked to that product's offers. When several valid totals exist on one day, the chart uses the lowest recorded total for that day. History is evidence of checks stored by SupplementScout, not a promise of continuous monitoring or the lowest price across the entire UK market.
Sources and limitations
- Offer data comes from retailer sources mapped to reviewed catalogue records.
- Retailer coverage is not the whole UK market and varies by product.
- Prices, delivery terms and stock can change after the recorded check.
- The retailer's checkout is the final source for the amount paid.
- SupplementScout compares shopping information and does not provide medical advice.