Green tea extract is bought for its polyphenols and EGCG, but the caffeine comes along with them. Leaf naturally contains it, and extraction concentrates it unless a decaffeination step removes it. For a formulator, the caffeine figure decides the label, the serving size and sometimes the market. Here is how much there is in each grade, and how to work out the milligrams per serving.
Caffeine by Grade
| Grade | Caffeine specification | Per 250 mg of extract | Per 500 mg of extract |
|---|---|---|---|
| Standard grades: 50%, 90% and 98% polyphenols | Not more than 10.0%, declared per batch | Up to 25 mg | Up to 50 mg |
| Reference batch: 90% polyphenols / 80% catechins (CoA SVB-COA-GT90-0426-01) | 6.2% found | 15.5 mg | 31 mg |
| Decaffeinated grade | 0.5% or less | Up to 1.25 mg | Up to 2.5 mg |
The per-serving figures are arithmetic from the specification. To get them, multiply the milligrams of extract per serving by the caffeine percentage and divide by 100. Use the limit for label safety margins. Use the batch result from the certificate when you want the actual figure for a lot. Buyers who need a specific caffeine target can set it at order.
Why the Figure Varies
Caffeine in leaf varies with cultivar, plucking standard (young shoots carry more) and season. The extraction solvent and any purification step decide how much of it reaches the extract. A high-polyphenol grade is not automatically low in caffeine. Purifying toward catechins can concentrate or remove caffeine depending on the process. That is why caffeine is a separate specification line and not something you can infer from the polyphenol percentage.
How Caffeine Is Measured
Caffeine is measured by HPLC with UV detection. ISO 10727:2002 is the international standard HPLC method for caffeine in tea and instant tea in solid form, and it covers green, black and decaffeinated products. Ask that the certificate name the method, and that caffeine is reported from the same run as the catechins where the lab does both. For how polyphenol and EGCG figures are measured, see catechins and EGCG assay explained and UV vs HPLC standardisation.
Intake Reference Points
The European Food Safety Authority’s 2015 scientific opinion on the safety of caffeine reached three conclusions:
- Single doses up to 200 mg raise no safety concern for healthy adults.
- Habitual intakes up to 400 mg a day raise no safety concern for healthy adults.
- For pregnant women, intakes up to 200 mg a day raise no concern for the foetus.
At the standard-grade limit, 400 mg of caffeine would take 4 g of extract a day. Supplement servings are far smaller. In practice, caffeine matters for labelling, for “caffeine-free” or evening-use positioning, and for combination products that already contain caffeine.
EGCG, not caffeine, is the tighter constraint on green tea extract dosing. EFSA’s 2018 opinion on green tea catechins found that EGCG intakes of 800 mg a day or more from supplements were associated with raised liver transaminases. The EU then restricted green tea extracts containing EGCG in foods under Regulation (EU) 2022/2340: a daily portion must contain less than 800 mg, with labelling conditions attached. The EGCG dosage guide covers this in detail.
Choosing a Grade
- Standard grade where some caffeine is acceptable or wanted. This is the usual choice for energy and weight-management formulas.
- Decaffeinated grade for caffeine-free claims, products for evening use, or formulas for consumers who limit caffeine.
- Custom target where a combination product needs a precise total caffeine per serving.
All three are specified on our green tea extract powder page, with caffeine declared on every certificate. For grade selection more broadly see the green tea extract buyer’s guide.
Green tea extract with the caffeine declared
Tell us the polyphenol grade, the caffeine limit you need and the quantity. We send the specification and a reference certificate.