Black Tea Caffeine: How Much Caffeine is in Your Cup?
By Merey Tleugazin Published March 15, 2026 Updated August 2, 2026 8 min read
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.
How many cups of black tea equal one cup of drip coffee?
One 240 ml cup of drip coffee contains 96 mg while one 240 ml cup of black tea contains 47 mg, so a single drip coffee equals about 2.0 cups of black tea by caffeine content using the dataset used here (96 mg ÷ 47 mg ≈ 2.04). Equivalency ratio is the amount of caffeine in one drink divided by the amount in another.
Practical example: to match a 240 ml drip coffee (96 mg, dataset), you would need two 240 ml black teas (2 × 47 mg = 94 mg), which is slightly below the coffee's 96 mg; three black teas would exceed it (3 × 47 mg = 141 mg). Use our side-by-side drink comparison to convert mixed servings, and convert every beverage to mg before summing.
How many 240 ml black teas meet the FDA 400 mg and the 200 mg pregnancy limit?
Four 240 ml black teas (4 × 47 mg = 188 mg) remain under the FDA's 400 mg/day recommendation for healthy adults, while five 240 ml black teas (5 × 47 mg = 235 mg) still stay below 400 mg but exceed common pregnancy guidance near 200 mg/day set by EFSA and echoed by clinical bodies. Daily-limit threshold is the recommended maximum total caffeine per day from all sources.
Specifically, the dataset lists one 240 ml black tea as 47 mg, so: 4 cups = 188 mg (dataset math), 5 cups = 235 mg (dataset math), and the EFSA 2015 opinion places a 200 mg/day pregnancy-oriented guideline (200 mg/day, EFSA), so pregnant people should compare total mg against that value and see our caffeine and pregnancy guide for further context.
How much caffeine accumulates if you drink multiple cups during the day?
Caffeine accumulation is the sum of residual milligrams from all earlier doses after first-order elimination; using the population-average half-life of 5.7 hours for this guide, two 240 ml black teas drank 3 hours apart produce about 79 mg immediately after the second cup and about 38 mg remaining 6 hours after the second cup. First-order elimination is the pharmacokinetic pattern where a constant fraction of the substance is removed per unit time.
Worked example using the decay model for this guide (half-life = 5.7 h): first cup 47 mg at time 0; after 3 h ≈ 69% remains, so remaining = 47 × 0.69 ≈ 32.4 mg; a second 47 mg cup at 3 h makes an immediate total ≈ 32.4 + 47 = 79.4 mg (dataset math). Six hours after the second cup (9 h after the first) use the guide's approximations: 9 h ≈ 33% remaining for a single dose, so first-cup residue ≈ 47 × 0.33 = 15.5 mg and second-cup residue (6 h later ≈ 48%) ≈ 47 × 0.48 = 22.6 mg, total ≈ 38.1 mg remaining (all arithmetic shown). For automated tracking of dose timing and residual mg use our caffeine half-life calculator or log each serving with a tracker such as CoffeeLog to sum decays accurately.
How do I estimate caffeine in a larger or nonstandard cup of black tea?
Black tea in the dataset is 47 mg per 240 ml which equals about 19.6 mg per 100 ml, so you can scale by volume to estimate caffeine for other cup sizes: for a 355 ml cup the estimate is 19.6 mg/100 ml × 355 ml ≈ 69.6 mg (dataset-derived scaling). Concentration is milligrams of caffeine per 100 milliliters for a given beverage.
Examples using the dataset-derived concentration: 300 ml ≈ 19.6 × 3.00 = 58.8 mg; 355 ml ≈ 19.6 × 3.55 = 69.6 mg; and a 240 ml cup remains 47 mg (dataset). If you change steep time or leaf amount, scale these estimates up or down (longer steep times increase extraction); see our tea caffeine content guide and the black vs green tea comparison for brew-factor details.
Is switching from coffee to black tea an effective way to reduce caffeine intake?
Yes — switching one 240 ml drip coffee (96 mg, dataset) for one 240 ml black tea (47 mg, dataset) cuts that serving's caffeine roughly in half (about 49% reduction by mg). Reduction per swap is the absolute difference in mg between the two servings.
Concrete math: swapping a single drip coffee for black tea saves 96 − 47 = 49 mg (dataset arithmetic); doing that swap twice a day saves about 98 mg, which is roughly one-quarter of the FDA's 400 mg/day limit. If you want finer control, use our caffeine comparison tool or the caffeine dosage guide to plan swaps and track cumulative totals.
Bottom line
A standard 240 ml cup of black tea contains 47 mg of caffeine according to the dataset used here, which is about half the caffeine of a 240 ml drip coffee (96 mg, dataset). The population-average half-life used in this guide is 5.7 hours, so single-cup decay arithmetic gives ~32 mg remaining after 3 hours and ~24 mg after one half-life (5.7 h); those numbers come from the first-order elimination model applied to the dataset's 47 mg serving.
For daily limits, the FDA recommends about 400 mg/day for healthy adults and the EFSA 2015 opinion and clinical bodies put pregnancy guidance near 200 mg/day; using the dataset, four 240 ml black teas = 188 mg (dataset math) and five = 235 mg (dataset math), so pregnant people should compare totals against 200 mg/day and others against 400 mg/day. To plan timing and accumulation, add per-serving mg and apply the 5.7-hour half-life decay math shown above or use our latest-cup-before-bed calculator and half-life calculator for precise residual estimates.
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.
Can several cups of black tea equal the caffeine in an energy drink?
Yes. The dataset lists a 250 ml Red Bull at 80 mg; two 240 ml black teas (2 × 47 mg = 94 mg, dataset math) already exceed one Red Bull's 80 mg by 14 mg.