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Is there caffeine in tea?
Executive Summary
Tea made from the Camellia sinensis plant—black, green, white, and oolong—contains measurable caffeine, but amounts vary widely by type and preparation; herbal tisanes generally do not contain caffeine except for exceptions like yerba mate. Multiple recent analyses report typical ranges for brewed tea from roughly 15–80 mg per 6–8 oz cup, with black teas toward the higher end and white teas toward the lower end, and decaffeination removing most but not all caffeine in some products [1] [2] [3]. This note lays out the key factual claims, the evidence and dates behind them, and important caveats about variability, health guidance, and potential messaging motives from industry or advocacy sources.
1. Why experts say “yes”: tea generally contains caffeine — and here’s how much to expect
All mainstream analyses agree that true tea contains caffeine because tea leaves naturally contain the compound; black, green, oolong, and white teas are all derived from Camellia sinensis and therefore carry caffeine in varying quantities. Reported central estimates cluster around 20–50 mg per 6–8 ounce serving for common tea types, with black tea often cited at roughly 30–50 mg, oolong around 30–40 mg, green roughly 20–40 mg, and white typically lower, often cited near 15–20 mg or reported as a wider range [1] [2] [4]. These figures come from aggregated sources including USDA-referenced analyses and tea-industry measurements; the divergence between studies reflects differences in cup size definitions and measurement methods [1].
2. What changes the caffeine count: brewing, leaf form, and plant factors
Caffeine content is not a fixed property of a brand label; brewing variables and plant factors shift the final amount a drinker ingests. Steep time, water temperature, leaf-to-water ratio, and whether you use whole leaves, fannings, or powdered matcha all alter extraction—longer, hotter steeps and higher leaf mass yield more caffeine. Biological factors such as cultivar, plant age, and growing region also influence the raw caffeine in the leaves, producing overlapping ranges across tea types in lab tests [1] [4]. Matcha and concentrated preparations can concentrate caffeine per serving; conversely, decaffeinated teas undergo processes that remove most caffeine but can leave trace amounts [5] [3].
3. Exceptions and lookalikes: herbal teas, yerba mate, and decaf complications
Not all “tea-like” beverages contain caffeine: herbal tisanes (chamomile, rooibos, peppermint) are typically caffeine-free because they come from non-Camellia plants, while yerba mate—often marketed alongside teas—naturally contains caffeine and can be as potent as or stronger than some teas. Decaffeinated teas are widely available and remove most caffeine, but analyses caution that decaf is rarely 100% caffeine-free and residual amounts can remain depending on the decaffeination method [1] [2] [3]. This distinction is a common source of consumer confusion when labels use “tea” loosely, so ingredient listing and product descriptors matter for accurate expectations [2] [4].
4. Health context: how tea’s caffeine compares to coffee and daily limits
Tea generally delivers less caffeine per cup than coffee, with an average brewed coffee cup carrying substantially more—studies cite typical coffee ranges of about 90–200 mg per 8-ounce cup versus tens of milligrams for tea. Regulatory and health bodies often reference an upper adult limit of about 400 mg/day of caffeine from all sources; tea consumption usually sits well below that threshold unless consumed in large quantities or in concentrated forms like multiple matcha servings [6]. Tea also contains L-theanine and other compounds that modulate caffeine’s subjective effects, which researchers note can change the experience of alertness compared with coffee [2] [4].
5. Why messaging and data vary: sources, methods, and possible agendas
Reported caffeine ranges differ because studies use different cup sizes, extraction methods, and measurement standards, and because industry groups or retailers may present averages favorable to product positioning. Nutrition summary pieces synthesize USDA data and academic measurements and tend to emphasize ranges and variability, while some tea-industry content highlights calming compounds like L-theanine or promotes lower caffeine figures for marketing appeal [1] [2]. Consumers should consult product labels, look for serving-size definitions, and recognize that percent differences across sources reflect methodological choices rather than contradiction about the core fact that tea contains caffeine [1] [4].