How we check a label

1. What we compare

For each ingredient we take the amount in one serving as printed (or in the number of scoops you set on a product page) and compare it with thelow end of the research dose: the amount studies used. We report what the label contains and what studies used (“contains 1.6 g; studies use 3.2–6.4 g/day”). We don't make health claims.

Five ingredients are key, because they're the ones pre-workouts are bought for and the ones with established doses: caffeine, L-citrulline, beta-alanine, creatine and betaine. The headline verdict counts how many of the key ingredients on a label reach their research dose (“below research dose on 2 of 4 key ingredients”).

2. The verdicts

• Effective dose: the amount is at or above the low end of the research dose.
• Below research dose: the amount is below the low end. For ingredients that work through daily use over weeks (creatine, beta-alanine, betaine), we say so: a lower amount still builds up, just more slowly.
• Hidden in a blend: the label doesn't disclose the amount. We show the most it could contain (section 4).
• Too much: above an upper reference. For caffeine, one serving of 400 mg or more, because that's the whole daily amount the FDA cites for most adults.
• Unlisted caffeine: a caffeine-containing ingredient (green tea extract, guarana, yerba mate, coffee bean, kola nut and similar) appears without the label stating how much caffeine it adds. We never guess that amount.
• Not graded: there's no research dose we grade the ingredient against. Vitamins and minerals are graded only on their own supplement pages (vitamin C, zinc, magnesium, electrolytes): their research doses come from daily-intake studies, not exercise ones, so a pre-workout's added vitamin C or magnesium isn't graded.

3. Bodyweight

Caffeine studies dose by bodyweight (3–6 mg per kg). Product pages use 75 kg and say so; the caffeine calculator lets you enter your own weight, in your browser only.

4. Proprietary blends

US labels must list the ingredients of a proprietary blend in order of weight, heaviest first (21 CFR 101.36). From the blend's total and the ingredient's position we can bound its amount:

• the ingredient in position n of k can be at most total ÷ n;
• the first ingredient is at least total ÷ k.

When a blend lists the same ingredient more than once (caffeine anhydrous 4th and caffeine citrate 6th, say), we bound those rows together with the same heaviest-first rule, not each on its own: two rows can hold more than either one. The least counts only rows that are the ingredient itself, because a form such as citrulline malate is only part citrulline.

If even the maximum is below the research dose, we say so. Anything else stays “hidden”: a bound isn't an amount.

5. Forms and conversions

Some forms aren't 100% the ingredient. We convert only where the rule is explicit and documented, and only when the label doesn't state the active amount itself. Every conversion used on a page is listed on that page.

• Alpha-Glyceryl Phosphoryl Choline 50% / Alpha-GPC 50% count as 1/2 Alpha-GPC. ASSUMPTION: a 50% alpha-GPC powder is counted as half its printed weight, as its name says. Used only when the label does not state the alpha-GPC itself.
• Arginine Nitrate counts as 73.4% of L-Arginine. ASSUMPTION: arginine nitrate (1:1) is counted as the L-arginine in it: 174.20 ÷ 237.21 g/mol = 73.4% of the printed weight. Used only when the label does not state the arginine itself.
• Caffeine Citrate counts as 1/2 Caffeine. ASSUMPTION: caffeine citrate is counted as 50% caffeine by weight, the convention used for caffeine citrate dosing. Applied only when the label does not state the caffeine amount.
• Calcium Beta-Hydroxy Beta-Methylbutyrate / Calcium Beta-Hydroxy Beta-Methylbutyrate Monohydrate / Calcium beta-Hydroxy-beta-Methylbutyrate / Calcium Beta-Hydroxy-Beta-methylbutyrate Monohydrate / Calcium HMB / HMB (as Calcium HMB) count as HMB, weight as printed. ASSUMPTION: calcium HMB is counted as printed, because the HMB studies mostly gave calcium HMB and reported the dose as the calcium salt. Used only when the label does not state the HMB in it.
• Choline Bitartrate counts as 41.1% of Choline. ASSUMPTION: choline bitartrate (1:1) is counted as the choline in it: 104.17 ÷ 253.25 g/mol = 41.1% of the printed weight. Used only when the label does not state the choline itself.
• Citrulline Malate 2:1 / L-Citrulline DL-Malate 2:1 / L-Citrulline Malate 2:1 count as 2/3 L-Citrulline. ASSUMPTION: "2:1" is read as a weight ratio (2 parts L-citrulline to 1 part malic acid), so 2/3 of the stated weight is counted as L-citrulline. Applied only when the label does not state the citrulline amount itself. If 2:1 were a molar ratio the share would be about 72% (2 x 175.19 / (2 x 175.19 + 134.09)); the weight reading gives the lower citrulline figure.
• Citrulline Nitrate counts as 73.5% of L-Citrulline. ASSUMPTION: citrulline nitrate (1:1) is counted as the L-citrulline in it: 175.19 ÷ 238.20 g/mol = 73.5% of the printed weight. Used only when the label does not state the citrulline itself.
• Creatine Hydrochloride counts as 89.0% of Creatine Monohydrate. ASSUMPTION: creatine HCl is counted as the creatine monohydrate it equals: the same 131.13 g/mol of creatine sits in 167.59 g/mol of the hydrochloride and 149.15 g/mol of the monohydrate, so 1 g = 0.89 g monohydrate. Used only when the label does not state the creatine itself.
• Creatine Nitrate counts as 76.8% of Creatine Monohydrate. ASSUMPTION: creatine nitrate (1:1) is counted as the creatine monohydrate it equals: 149.15 ÷ 194.14 g/mol = 76.8% of the printed weight. Used only when the label does not state the creatine itself.
• DHA Ethyl Ester / Docosahexaenoic Acid Ethyl Ester count as DHA, weight as printed. ASSUMPTION: an ethyl-ester amount is counted as printed. If the label gives the ester's weight, the fatty acid in it is about 9% less, so this can count up to about 9% too much. Used only when the label does not state the fatty acid itself.
• DL-Methionine counts as 1/2 L-Methionine. ASSUMPTION: DL-methionine is an equal mix of the L and D forms, and only L-methionine is the essential amino acid, so half the amount is counted. Used only when the label does not state the L-methionine in it.
• DL-Phenylalanine counts as 1/2 L-Phenylalanine. ASSUMPTION: DL-phenylalanine is an equal mix of the L and D forms, and only L-phenylalanine is the essential amino acid, so half the amount is counted. Used only when the label does not state the L-phenylalanine in it.
• Eicosapentaenoic Acid Ethyl Ester / EPA Ethyl Ester count as EPA, weight as printed. ASSUMPTION: an ethyl-ester amount is counted as printed. If the label gives the ester's weight, the fatty acid in it is about 9% less, so this can count up to about 9% too much. Used only when the label does not state the fatty acid itself.
• L-Arginine Hydrochloride counts as 82.7% of L-Arginine. ASSUMPTION: L-arginine hydrochloride is counted as the L-arginine in it: 174.20 ÷ 210.66 g/mol = 82.7% of the printed weight, taking that weight as the hydrochloride salt. Used only when the label does not state the arginine itself.
• L-Histidine HCl / L-Histidine Hydrochloride count as 74.0% of L-Histidine. ASSUMPTION: L-histidine hydrochloride is counted as the monohydrate sold for supplements, 74.0% histidine by weight (155.15 / 209.63). If it is the anhydrous salt it is 81.0%, so this can only count too little, never too much. Used only when the label does not state the histidine in it.
• L-Lysine HCl / L-Lysine Hydrochloride / L-Lysine Hydrochloride, Micronized / Micronized L-Lysine HCl count as 80.0% of L-Lysine. ASSUMPTION: L-lysine hydrochloride is 80.0% lysine by weight (146.19 / 182.65). Used only when the label does not state the lysine in it.

Forms we recognise but don't convert (shown as not graded): Beet, Beet Juice, Beet Root, Beet Root Extract, Beet Root Extract 4:1, Beet Root Extract, Powder 4:1, Beet Root Powder, Beet, Powder, Beetroot, Beetroot, Powder, Beta vulgaris, Citrulline Malate, Di-Caffeine Malate, Dicaffeine Malate, L-Citrulline Malate, Theobromine Hydrochloride.

Label names we don't recognise are never matched by guesswork: they stay unmatched, shown as not graded, until the exact name is added as a known spelling of an ingredient.

6. Scoops to an effective dose

For each key ingredient below its research dose: scoops needed = low end of the research dose ÷ amount per scoop. We show the caffeine those scoops would bring, and flag it when it goes over 400 mg.

7. Supplements outside pre-workouts

Beta-alanine and creatine supplements are taken daily, often several servings a day, and the research dose is a daily amount. So for these products we take the label's own directions: the amount per serving times the servings a day it tells you to take. When the directions give a range ("2 tablets one to two times daily"), the verdict judges the most they give in a day, and the page shows the least as well. Servings a day come from the NIH Dietary Supplement Label Database's record of the label, or from the printed directions, which every product page quotes. Rankings start with the products that reach the research dose when taken as directed, then count the least their directions give a day, but only up to the top of the research range: directing more than studies use earns nothing extra.

Citrulline and caffeine work as one dose before training, not by building up. For a stand-alone citrulline product or a caffeine pill, the verdict judges one serving, and the page says how many servings reach the research dose (for caffeine, what one serving is as a share of the dose at 75 kg instead, since more pills at once can pass 400 mg). When a caffeine label's directions allow more than 400 mg in a day, the page says so.

EAA products are judged on the total of the nine essential amino acids in one serving, against the 10–12 g in one dose in the ISSN's 2018 review. We add up the label's own amounts, counting salt forms as the amino acid in them (lysine hydrochloride as 80% lysine, histidine hydrochloride as 74% histidine) and a DL form as half L. When a blend holds nothing but essential amino acids and gives only its total, we count that total as printed; when a blend mixes them with other things and hides the amounts, the total is hidden, and the page says the most it can be. BCAA products are judged on their leucine against the 2–3 g in one dose in the same review and the ISSN's protein position stand.

Each EAA and BCAA page also checks the mix. The WHO's adult requirement for each essential amino acid (WHO/FAO/UNU 2007, Technical Report 935, Table 23) is scaled to a 10 g dose, and every amino acid in one serving is compared with its share: leucine 2.12 g, lysine 1.63 g, valine 1.41 g, phenylalanine (with tyrosine) 1.36 g, isoleucine 1.09 g, threonine and methionine (with cysteine) 815 mg each, histidine 543 mg and tryptophan 217 mg. No study gave the amino acids one at a time at these amounts, so this is a check of the mix, not a verdict: the verdict stays the total.

8. Labels

Most labels come from the NIH Dietary Supplement Label Database (DSLD). Caffeine pills sold as over-the-counter drugs come from their Drug Facts label on DailyMed (US National Library of Medicine). The rest are entered by hand from the brand's own page, with who entered them and from what source. Every product page shows the date of the label it is based on. DSLD lags the shelf by months, so labels change: you can report a new one from any product page.

National Institutes of Health, Office of Dietary Supplements. Dietary Supplement Label Database, 2026. https://dsld.od.nih.gov/.

9. Reference doses (1.11)

10. Privacy

The caffeine calculator and “paste a label” run entirely in your browser. Your bodyweight, caffeine intake and pasted labels are never sent to us or to our analytics. Our analytics are self-hosted and count page views only.

11. Corrections

The data behind every page is kept in version control. When a verdict, label or reference dose changes, the change and its reason go in the public corrections log.