Black Tea Caffeine: Everything You Need to Know

A 240 ml cup of black tea has 47 mg of caffeine.

• A standard 240 ml cup of black tea contains 47 mg of caffeine.
• Black tea typically has about 47 mg vs. green tea 28 mg and white tea 16 mg per 240 ml.
• Compared with drip coffee (240 ml, 96 mg), black tea has roughly 49% of the caffeine per cup.
• After ~6 hours about 48% of a dose remains—so from 47 mg, ~22.6 mg is left.

Caffeine content in black tea: the baseline

Across published nutrient data a 240 ml (8 fl oz) serving of brewed black tea is listed at 47 mg of caffeine (≈19.6 mg/100 ml). Those are average values collected by major datasets and commonly cited by USDA FoodData Central. That single number is a good starting point when you plan intake or compare beverages.

How black tea compares: table of common drinks

Use this quick table to compare common teas, coffees and energy drinks by the dataset values.

Why black tea numbers vary: leaf, steeping and serving size

Leaf type and processing

Black tea is fully oxidized; oxidation concentrates certain alkaloids and produces a higher average caffeine than green or white tea. Within black tea, cultivars and plucking standard matter: a fine bud-and-leaf harvest (breakfast blends) tends to yield more caffeine per cup than coarse broken-leaf blends.

Steeping time, water temperature, and tea-to-water ratio

Longer steep time and hotter water extract more caffeine. A 1–2 minute bag steep yields less caffeine than a 4–5 minute steep; a stronger leaf-to-water ratio scales caffeine up roughly linearly. Bag tea often yields values close to the dataset averages; loose-leaf strong brews can exceed them.

Serving size

Dataset values use 240 ml. If you sip a 360 ml mug, multiply mg per 240 ml by 1.5 to estimate total caffeine.

Black tea vs coffee and energy drinks: practical comparisons

Black tea (47 mg per 240 ml) sits between low-caffeine green/white tea and brewed coffee. Drip coffee at 240 ml contains 96 mg—so a cup of black tea delivers roughly half the caffeine of an equivalent cup of drip coffee. Espresso shots are concentrated: a single 30 ml shot contains 63 mg.

How long caffeine from black tea stays in your body (decay math)

Population-average half-life is about 5.7 hours; caffeine declines roughly by half every 5.7 hours. Practically that means after 3 hours ≈69% remains, after 6 hours ≈48%, after 9 hours ≈33%, after 12 hours ≈23% remains.

Those are population averages. Genetics, liver function, pregnancy, some medications and smoking change the half-life. For example, pregnancy prolongs clearance (Mayo Clinic notes altered metabolism), while smoking speeds it up.

Health, safety and timing

Regulatory guidance: the U.S. Food and Drug Administration recommends up to 400 mg/day of caffeine for healthy adults; for pregnant individuals many authorities (including EFSA and clinical guidance) advise keeping intake near or below 200 mg/day. The American Academy of Pediatrics discourages routine caffeine use in adolescents. These limits help reduce risks of insomnia, palpitations and anxiety.

Timing: because meaningful caffeine remains even 6–12 hours after a cup, avoid late-afternoon cups if you want minimal sleep disruption. If you need precise tracking of intake and timing, use an app like CoffeeLog to log drink type, serving and when you consumed it.

Practical tips to lower or raise caffeine from black tea

• Reduce steep time: cut from 4–5 minutes to 1–2 minutes to lower extraction.
• Use fewer tea leaves or a larger cup to dilute mg per serving.
• Choose white or green tea (16 mg or 28 mg per 240 ml) for lower caffeine.
• Try decaffeinated black tea (not in dataset—typically >90% reduction) if you need near-zero caffeine.

Measuring and tracking your intake

For day-to-day decisions convert drinks to mg and add them: two 240 ml cups of black tea (2 × 47 mg = 94 mg) plus a 240 ml drip coffee (96 mg) totals 190 mg. Tracking tools and apps like CoffeeLog make this arithmetic automatic and show timing, which is helpful since residual mg matter for sleep and sensitivity.

Sources and further reading: caffeine content values are drawn from standardized food composition datasets (USDA FoodData Central and industry published product data). For health guidance see the U.S. Food and Drug Administration, European Food Safety Authority, Mayo Clinic and American Academy of Pediatrics. This page is informational, not medical advice—consult a clinician for personalized recommendations.