A score is only useful if you can take it apart. This post opens up the VialScore formula: what goes in, how it is weighted, how the ranking order is decided — and where the formula stops and an editorial decision begins.
Four rules before any maths
Everything you see on VialScore follows four rules. They matter more than the decimals, so here they are first.
- Some shops are affiliate partners. We earn a commission when you buy from some listed shops through our links, and that can influence where they are placed. Scores of every other shop come from public information only.
- Scores are editorial estimates. Our editors estimate each criterion from what a shop publishes about itself. We have not run lab tests on any product.
- Unknown facts are shown as “not published”. If a shop doesn’t state its payment methods or refund policy, the spec sheet shows a dash — not a guess.
- Reviews only come from verified emails. No imported, written-in-house or purchased reviews. A shop with zero reviews shows zero.
The five criteria and their weights
Each shop gets a 0–10 score on five criteria. The overall score is a fixed weighted average:
| Criterion | Weight | What we look at |
|---|---|---|
| Purity & testing | 30% | Stated purity, independent HPLC/MS testing, batch-level COAs |
| Transparency | 20% | Identifiable operator, imprint, clear terms and contact options |
| Price & value | 20% | Price level, free-shipping threshold, how generous the codes are |
| Shipping | 15% | EU coverage, speed, discreet packaging, tracking |
| Support | 15% | Reachable contact channels and how problems get resolved |
In formula form: overall = 0.30·purity + 0.20·transparency + 0.20·price + 0.15·shipping + 0.15·support, rounded to one decimal.
Purity carries the most weight because it is the reason anyone cares about a research supplier in the first place. It is also the criterion where public evidence is thinnest — which is why a shop that publishes nothing about testing can’t score at the very top here.
A worked example
Take Peptid24’s current estimates: purity 8.3, transparency 7.1, price 9.0, shipping 8.8, support 7.6.
- 8.3 × 0.30 = 2.49
- 7.1 × 0.20 = 1.42
- 9.0 × 0.20 = 1.80
- 8.8 × 0.15 = 1.32
- 7.6 × 0.15 = 1.14
Sum: 8.17, shown as 8.2 — “Good”. The profile is visible in the numbers: strong on price (it publishes a range starting at €24.90 and ships free from €75), weaker on transparency (the operator isn’t clearly named on its product pages, and support runs through a single e-mail address).
Nexo Research and Europa-Peptide currently carry identical estimates — 8.6, 8.2, 8.8, 9.0, 8.4 — which gives both an overall of 8.6 — “Very good”. They publish the same core terms: a 60+ product catalog and free EU shipping from €99.
Why the ranking is not sorted purely by score
Here is the part most ranking sites don’t spell out. Affiliate partnerships can influence placement, so the Rank column is our order, not a pure sort by overall score.
We don’t hide that. Every column in the rankings table can be re-sorted by you — click “Purity” or “Price” and the table reorders on that criterion alone. The “Best by criterion” panel on the home page also ignores our order and shows the leader of each criterion on score alone. And the region filter keeps each shop’s overall rank, so a shop that is #12 overall stays #12 when you only look at Australia.
Most of the 45 shops in the index are smaller suppliers we researched through their public listings, many on PeptidesLookup. Their scores sit between 4 and 6 out of 10 — not because we know something bad about them, but because they publish little we can check: few have lab reports linked, and most have no verified buyer reviews yet. Each of those shop pages lists its sources.
Where the inputs come from
For every criterion we read what the shop publishes: product pages, terms, shipping information, contact options, imprint and any testing statements. Some examples of how that turns into a number:
- A stated purity claim (such as Peptid24’s “≥98%”) supports the purity score, but a claim on its own is worth less than a published, batch-specific certificate.
- A free-shipping threshold feeds the price score. €75 beats €99 for small orders; “not published” earns nothing.
- Look-alike domains cost transparency points for no fault of the shop — buyers can land on the wrong site. Europa-Peptide’s spec sheet warns about this explicitly.
When better evidence appears — a shop publishes lab reports, or verified buyers start reporting on shipping — the estimate moves.
What a dash means
Our spec sheets list up to 18 facts per shop. Many are empty for now: payment methods, refund policy, founding year, headquarters, public COAs. Each empty field shows a dash with a tooltip reading “not published by the shop”. It is a statement about the shop’s disclosure, not about its quality — but it is also why transparency and purity scores have room to grow.
The short version
Weighted formula, editorial inputs from public information, affiliate placement disclosed, gaps marked rather than filled. If you disagree with a weight, the criterion scores are all on the shop page — re-run the maths with your own priorities. The data is there to be used, not just believed.
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