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How much caffeine is in a standard cup of tea (mg)?
Executive Summary
A standard cup of tea most often contains between about 15 mg and 70 mg of caffeine, with multiple credible sources clustering typical brewed servings in the 30–50 mg range; exact values depend strongly on tea type and brewing variables [1] [2] [3]. Recent itemized data and government-adjacent compilations confirm that black teas tend toward the higher end (around 47–50 mg per 8 oz) while green and white teas commonly fall lower, and herbal or decaffeinated varieties contain negligible or trace caffeine [4] [5] [6].
1. What claim-summaries did the sources make that matter to consumers?
The assembled analyses present repeating claims: black tea averages roughly 47–50 mg of caffeine per 8-ounce cup, green tea typically contains somewhere in the 20–45 mg band, and white tea is usually lower, sometimes reported per-gram rather than per-cup which yields mixed numbers [1] [7] [5]. Several sources emphasize wide ranges rather than single-point estimates—examples include a low–high span of 15–70 mg stated explicitly, and multiple items noting that decaffeinated teas can still contain small residual caffeine amounts [7] [2] [5]. The sources also repeatedly flag that brewing time, water temperature, leaf amount, and leaf cut or form (bag vs. loose) materially alter extraction, so the headline numbers are averages, not guarantees [1].
2. How do the most recent sources align or disagree on the numbers and why?
The most recent item in the set is a caffeine chart referenced in mid-2025 which compiles values but does not itself publish a single definitive per-cup number; it supports the broader consensus that brewed tea contains materially less caffeine than coffee [6]. A December 2024 nutritionist summary reports black tea around 47 mg and green about 33 mg per cup, aligning with earlier 2019–2023 summaries that placed black tea near 50 mg and green tea in the 20–45 mg range [4] [1] [2]. Differences stem from varying serving-size assumptions (6 oz vs. 8 oz), instant vs. brewed comparisons, and whether per-gram metrics were converted to per-cup, which explains apparent contradictions between sources that otherwise agree on the central tendency [3] [1] [5].
3. Why do reported ranges vary so much — the science behind the spread?
Caffeine extraction from Camellia sinensis leaves depends on quantifiable variables: leaf type and position on the plant, cultivar, leaf processing, dose of leaf per cup, steep time, and water temperature. Sources repeatedly note that longer steeping and hotter water extract more caffeine, and that bagged, finely cut leaves often yield higher extraction per gram than whole-leaf preparations—so a “standard cup” is not standard in practice [1] [5]. Some analyses report caffeine per gram metrics for white tea, which inflate apparent variance when readers expect per-cup numbers; other sources differentiate instant, brewed, and decaffeinated products, adding further dispersion to headline figures [1] [7] [3].
4. How do these tea numbers compare to coffee and public health limits?
Across the datasets, tea’s caffeine content is consistently lower than coffee: multiple sources contrast an average 8-ounce brewed coffee (~95 mg, with broad 90–200 mg ranges) versus tea’s typical 30–50 mg [1]. Public health guidance referenced in these analyses notes a common safety benchmark of up to 400 mg of caffeine per day for most healthy adults, which translates into several cups of tea before reaching that ceiling; however, sensitivities, pregnancy guidance, and stimulant interactions mean individual safe amounts vary [1] [2]. The documents also highlight that decaffeinated tea is not always zero and that herbal tisanes from non-tea plants are effectively caffeine-free, which matters for consumers aiming to minimize intake [5] [4].
5. Bottom line for a practical “standard cup” number and consumer caveats
If a single, practical figure is required for planning or labeling, use ~40–50 mg of caffeine per 8-ounce cup for black tea and roughly 20–35 mg for green tea as defensible central estimates supported across sources; white tea and specific products may be lower or reported per gram [1] [4] [2]. Remember that these are averages: a tightly packed, long-steeped brew can approach the upper ranges reported (60–90 mg in some lists), while short steeps and decaffeination can yield figures in the teens or single digits [7] [5]. For health decisions, use the higher end of reported ranges when assessing cumulative daily intake and consult product-specific lab data where precision matters [6] [1].