Black Tea vs Green Tea: Caffeine Content Explained
A 240 ml cup of black tea contains 47 mg of caffeine while the same volume of green tea contains 28 mg, according to USDA FoodData Central.
- Black tea (240 ml): 47 mg; green tea (240 ml): 28 mg — black ≈ 19 mg more.
- Matcha (1 tsp, 240 ml) is higher at 70 mg because you consume whole leaf.
- Compared with coffee: a 240 ml drip coffee is 96 mg; cold brew is 200 mg.
- Population-average caffeine half-life ≈ 5.7 hours — from 47 mg, ~23 mg remains after 6 h.
Caffeine basics in tea
Caffeine is a plant alkaloid present in Camellia sinensis leaves. Measured values vary by cultivar, leaf age and preparation; USDA FoodData Central lists standard reference amounts used on nutrition labels. Tea also contains L-theanine and other compounds that modify perceived alertness compared with coffee.
Black tea caffeine content
Standard black tea is oxidized during processing, which does not create caffeine but is correlated with the use of older, larger leaves and stronger brews that often yield more caffeine. The dataset value for a 240 ml cup of black tea is 47 mg (19.6 mg/100 ml).
Green tea caffeine content
Green tea is minimally oxidized and generally brewed at lower temperatures; the dataset value for a 240 ml cup of green tea is 28 mg (11.7 mg/100 ml). That makes a typical black cup about 68% higher in caffeine than a typical green cup on a per-cup basis.
Direct comparison table: common teas and coffee (serving size and mg)
| Beverage | Serving | Caffeine (mg) |
|---|---|---|
| Black tea | 240 ml | 47 mg |
| Green tea | 240 ml | 28 mg |
| Oolong tea | 240 ml | 37 mg |
| White tea | 240 ml | 16 mg |
| Matcha (1 tsp) | 240 ml | 70 mg |
| Chai latte | 240 ml | 50 mg |
| Yerba mate | 240 ml | 85 mg |
| Drip coffee | 240 ml | 96 mg |
| Cold brew | 240 ml | 200 mg |
Factors that change tea caffeine (what actually moves the number)
Leaf type and part
Young buds and smaller leaves typically contain more caffeine per gram than older, coarser leaves. Matcha is highest among teas in the dataset (70 mg) because you ingest the whole leaf powder rather than an infusion.
Processing and oxidation
Oxidation (black vs green) changes flavor more than caffeine chemistry; however, traditional black blends are often used in stronger, longer steeps that extract more caffeine.
Brewing variables
Water temperature, steep time and leaf amount are the primary levers: hotter water and longer steep increase extraction. A tea bag steeped vigorously can match or exceed the caffeine of a lightly steeped loose-leaf green cup.
How brewing affects caffeine: practical rules
To lower caffeine: use cooler water, shorter steeps, fewer grams of leaf, or choose white/green teas. To increase caffeine: use more leaf, hotter water, longer steep, or consume powdered whole-leaf forms like matcha.
Decay over time: how much caffeine remains after hours
Average elimination follows a population half-life of about 5.7 hours. The table below shows approximate remaining caffeine from a single 240 ml cup of black (47 mg) and green (28 mg) tea at standard checkpoints (fractions: 3 h ≈ 69%, 6 h ≈ 48%, 9 h ≈ 33%, 12 h ≈ 23%).
| Time after drinking | Black tea (47 mg) remaining | Green tea (28 mg) remaining |
|---|---|---|
| 0 hours | 47 mg | 28 mg |
| ~3 hours (≈69%) | ≈32 mg | ≈19 mg |
| ~6 hours (≈48%) | ≈23 mg | ≈13 mg |
| ~9 hours (≈33%) | ≈16 mg | ≈9 mg |
| ~12 hours (≈23%) | ≈11 mg | ≈6 mg |
How tea stacks against coffee and energy drinks
Per the dataset, a 240 ml drip coffee (96 mg) has roughly double the caffeine of a 240 ml black tea (47 mg). Cold brew and many commercial coffee servings are far higher (cold brew 240 ml = 200 mg). Energy drinks and pre-workouts can contain 150–300 mg per serving; compare those labels directly.
Health limits, timing and special populations
For healthy adults the FDA guidance is an upper limit of about 400 mg/day. For pregnancy, many authorities (including EFSA and national guidelines) advise keeping intake near or below 200 mg/day; the American Academy of Pediatrics discourages caffeine for adolescents. If you have anxiety, insomnia or a medical condition, consult a clinician before changing intake.
Mayo Clinic notes caffeine can affect sleep for several hours; many people reduce intake at least 6 hours before bedtime. Use the decay table above to estimate residual caffeine at bedtime.
Tracking and practical tips
If you drink multiple cups or different beverages, add values into a tracker—CoffeeLog can log individual drinks and sum daily total so you stay under limits such as 400 mg/day. When choosing tea for lower caffeine, favor white or lightly brewed green, or switch to herbal (0 mg in the dataset) for caffeine-free options.
Bottom line
On a per-240 ml-cup basis: black tea ≈ 47 mg, green tea ≈ 28 mg. Brewing, leaf form (matcha), and serving size matter more than the black vs green label alone. Use the decay table to time caffeine for sleep and follow FDA/pregnancy/AAP guidance for limits.
Frequently asked questions
Which has more caffeine: black tea or green tea?
Per USDA data, a 240 ml cup of black tea has 47 mg while a 240 ml cup of green tea has 28 mg, so black typically contains about 19 mg more.
Can green tea ever have more caffeine than black tea?
Yes—if brewed much stronger (more leaf, hotter water, longer steep) a green cup can match or exceed a weak black brew; typical standard servings in the dataset still show black higher (47 mg vs 28 mg).
How does matcha compare to black and green tea?
Matcha (1 tsp in 240 ml) is listed at 70 mg in the dataset because you ingest the whole leaf powder, making it higher than both black (47 mg) and green (28 mg).
How long will tea caffeine affect my sleep?
With an average half-life of ~5.7 hours, roughly half the caffeine remains after about 6 hours; many people stop caffeine at least 6 hours before bedtime to avoid disruption (Mayo Clinic guidance).
Is tea safe during pregnancy and how much is allowed?
Pregnancy guidance typically recommends keeping caffeine near or below ~200 mg/day; check with your obstetric provider for personalized advice (EFSA and national guidelines reflect this conservative limit).
Are herbal teas caffeine-free?
Yes: the dataset lists herbal tea at 0 mg per 240 ml. Herbal tisane blends are caffeine-free because they do not contain Camellia sinensis leaves.