Black Tea Caffeine: How Much Caffeine is in Your Cup?
A 240 ml cup of black tea contains 47 mg of caffeine.
- 240 ml black tea: 47 mg caffeine per cup (19.6 mg/100 ml).
- English Breakfast (240 ml): 50 mg; Earl Grey (240 ml): 47 mg
- Drip coffee (240 ml): 96 mg200 mg
- Caffeine half-life (population average): ~5.7 hours — from 47 mg about 24 mg remains at 5.7 h and ~23 mg at 6 h.
- FDA recommends a maximum of 400 mg/day for healthy adults; pregnancy guidance is ~200 mg/day.
- Drip coffee (240 ml): 96 mg200 mg
Average caffeine in black tea (what the 47 mg means)
The commonly cited serving for tea is 240 ml (about 8 fl oz). In the dataset used here, black tea at that serving size contains 47 mg of caffeine — roughly 19.6 mg per 100 ml. That value is a population-average for standard brewing (bag or loose leaf, typical leaf weight and steep time).
Translated: a single 240 ml cup of black tea supplies less than half the caffeine of a typical 240 ml drip coffee (96 mg) and about one-quarter of a 240 ml cold brew (200 mg).
Caffeine levels by black tea type and comparable drinks
Different black blends and styles cluster around the same ballpark but can vary. The dataset lists English Breakfast at 50 mg and Earl Grey at 47 mg per 240 ml; both are typical breakfast-style black teas.
| Drink / serving | Volume | Caffeine (mg) | mg per 100 ml |
|---|---|---|---|
| Black tea | 240 ml | 47 mg | 19.6 |
| English Breakfast | 240 ml | 50 mg | 20.8 |
| Earl Grey | 240 ml | 47 mg | 19.6 |
| Green tea | 240 ml | 28 mg | 11.7 |
| Matcha (1 tsp) | 240 ml | 70 mg | — |
| Drip coffee | 240 ml | 96 mg | 40.0 |
| Cold brew | 240 ml | 200 mg | 83.3 |
| Red Bull | 250 ml | 80 mg | 32.0 |
Decaffeinated black tea: what to expect
"Decaf" black tea is not completely caffeine-free. Databases and lab measurements report small residual caffeine in decaffeinated tea; amounts vary by method and brand. Specific decaf black-tea numbers are not in this dataset, so treat them as estimates — many decaffeinated teas measure in single-digit milligrams per 240 ml.
If you need near-zero caffeine (for sleep or pregnancy), check lab-stated values on the package or choose herbal (0 mg in the dataset). For tracking low but nonzero levels, log decaf entries in an app such as CoffeeLog to sum total daily intake reliably.
How long caffeine from black tea stays in your body (decay math)
Caffeine follows first-order elimination; population-average half-life is ~5.7 hours. Practical approximations: after 3 h ≈69% remains, 6 h ≈48%, 9 h ≈33%, 12 h ≈23%.
| Time after drinking | % remaining (approx) | mg remaining from 47 mg |
|---|---|---|
| 0 h | 100% | 47 mg |
| 3 h | ~69% | ~32 mg |
| 5.7 h (half-life) | 50% | ~24 mg |
| 6 h | ~48% | ~23 mg |
| 9 h | ~33% | ~16 mg |
| 12 h | ~23% | ~11 mg |
Example: a 50 mg English Breakfast will leave about 25 mg at 5.7 hours and about 24 mg at 6 hours. Use these figures to plan evening caffeine cutoff times if you want minimal stimulant before sleep.
Factors that change black tea's caffeine content
- Leaf amount: more tea leaves (or a stronger bag) increases mg per cup.
- Steep time and water temperature: longer steeping and hotter water extract more caffeine; upping steep time by a minute or two can move a cup several mg higher.
- Leaf size and processing: fannings/CTC tea used for tea bags typically releases caffeine faster than whole-leaf orthodox black teas.
- Blend and origin: some blends (strong breakfast blends) are formulated with higher-caffeine leaves; Earl Grey's bergamot oil adds flavor but not more caffeine than other blacks in the dataset.
Black tea vs coffee and energy drinks — practical comparisons
On a mg-per-cup basis, black tea is modest: 47 mg per 240 ml versus drip coffee at 96 mg per 240 ml and cold brew at 200 mg per 240 ml. A single Red Bull (250 ml) is 80 mg. For people tracking total daily intake, several cups of black tea can add up—five 240 ml cups equals 235 mg.
Health, safety and timing guidance
FDA guidance for healthy adults caps recommended daily caffeine at about 400 mg; the data here should be combined across all sources (coffee, tea, energy drinks, pills). For pregnancy, many authorities advise limiting to ~200 mg/day (American College of Obstetricians and Gynecologists and other bodies); the dataset shows a single 240 ml black tea cup is ~47 mg. The American Academy of Pediatrics discourages caffeine use by adolescents.
Acute sensitivity varies: people with anxiety, arrhythmias, or on certain medications metabolize caffeine differently. For medical questions about pregnancy, arrhythmia, or drug interactions, consult a clinician. This guide is informational, not medical advice.
How to track and use these numbers
Track each beverage and serving size to sum daily intake. If you drink a 240 ml black tea (47 mg) at 4 pm and want minimal caffeine by bedtime, use the half-life math above: expect ~24 mg at 9:45 pm (5.7 h later). Apps like CoffeeLog automate logging, compute totals, and estimate residual caffeine using the population half-life.
Tip: when switching between tea and coffee, convert everything to mg before adding. For example, one 240 ml drip coffee + one 240 ml black tea = 96 + 47 = 143 mg total.
Frequently asked questions
How much caffeine is in a cup of black tea?
A standard 240 ml cup of black tea contains 47 mg of caffeine according to the dataset used here.
Is black tea stronger than coffee?
No — typical 240 ml drip coffee has 96 mg vs black tea's 47 mg. Stronger coffee styles (cold brew at 200 mg/240 ml) are much higher.
Does decaf black tea have zero caffeine?
Not usually. Decaffeinated black tea commonly contains trace amounts (single-digit mg per 240 ml); exact values vary by brand and process.
How long does caffeine from black tea affect me?
Population-average half-life is ~5.7 hours. From 47 mg, about 24 mg remains at 5.7 h and ~11 mg at 12 h (approximate).
Is black tea safe during pregnancy?
Guidelines generally advise limiting total caffeine to about 200 mg/day in pregnancy. One 240 ml cup of black tea (~47 mg) can be included within that limit; consult your provider for personal advice.
Can black tea disturb sleep?
Yes. With ~47 mg per 240 ml, drinking late afternoon or evening can leave tens of milligrams in your system at bedtime due to a ~5.7 h half-life; avoid late intake if sensitive.