Black Tea vs Green Tea: Caffeine Content Explained
By Merey Tleugazin Published November 8, 2025 Updated August 2, 2026 8 min read
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.
If I drink two cups of black tea and one green tea, how much caffeine will still be in my body after 6 hours?
Two 240 ml cups of black tea (2 × 47 mg = 94 mg) plus one 240 ml cup of green tea (28 mg) yield an initial dose of 122 mg (USDA FoodData Central lists black tea as 47 mg and green tea as 28 mg per 240 ml). First-order elimination is a process where the amount of a substance declines exponentially with a constant half-life.
Using a population-average half-life of 5.7 hours, the remaining caffeine after 6 hours is 122 mg × 0.5^(6/5.7) = 122 mg × ~0.48 ≈ 59 mg (the 5.7-hour half-life is the decay model we use, see Drake et al.). This arithmetic shows how modest tea-only intakes can still leave measurable caffeine after several hours; use our caffeine half-life calculator to apply the same formula to your actual drinks.
How do medications, smoking and hormones change how quickly tea caffeine is cleared?
Smoking, certain medications and hormonal status can meaningfully change caffeine clearance, so two identical cups can produce different residual caffeine in different people; the Mayo Clinic documents that smoking speeds caffeine metabolism while some drugs and pregnancy slow it (Mayo Clinic). CYP1A2 is a liver enzyme.
In practical terms, a smoker may metabolize caffeine faster (shorter effective half-life) whereas someone on CYP1A2-inhibiting medication or pregnant may have a longer effective half-life and therefore more residual caffeine at bedtime (Mayo Clinic; ACOG and EFSA guidance on pregnancy limits are relevant when advising intake). If you want a personalized estimate, combine the dataset values for each beverage with an adjusted half-life in our caffeine half-life calculator.
Are USDA cup values accurate for homemade tea and loose-leaf brews?
The USDA FoodData Central values (for example, black tea 47 mg and green tea 28 mg per 240 ml) are reference amounts meant for label and database consistency, not a guaranteed value for every homemade cup (USDA FoodData Central). USDA FoodData Central is the USDA's reference database for nutrient and component values used on labels and in research.
Actual home brew values vary by grams of leaf, water temperature and steep time; a lightly brewed loose-leaf green can fall below the USDA figure while a long-steeped bag or extra-strong black can exceed it. For help comparing brand and homemade options, see our tea caffeine guide and specific pages like Black Tea Caffeine: Everything You Need to Know and Green Tea Caffeine: A Comprehensive Breakdown.
How should I combine tea with coffee or energy drinks and still stay under safety limits?
The FDA advises healthy adults that about 400 mg/day is a practical upper guideline (FDA: "Spilling the Beans"). A serving of black tea is 47 mg per 240 ml (USDA FoodData Central lists this) and a 240 ml drip coffee is 96 mg (dataset), so one black cup plus one drip coffee equals 47 mg + 96 mg = 143 mg toward the 400 mg FDA guidance in the same sentence.
Use arithmetic from the dataset to plan combinations: for example, two black teas (2 × 47 = 94 mg) plus a 240 ml drip coffee (96 mg) totals 190 mg; adding a 240 ml cold brew (200 mg) would push you to 390 mg, just below the FDA 400 mg guideline (USDA FoodData Central for teas and dataset values for coffees; FDA). For step-by-step daily planning and to avoid exceeding limits in pregnancy or adolescence, consult our side-by-side drink comparison, the half-life calculator, and the pregnancy-specific guides such as Caffeine and Pregnancy: A Comprehensive Guide (EFSA and ACOG recommendations should guide pregnant intake).
How reliable are quick heuristics like "tea = half a coffee" for estimating alertness and residual caffeine?
Saying "a cup of black tea is half a cup of coffee" is a rough heuristic but not reliably accurate for milligram math: a 240 ml black tea is 47 mg while a 240 ml drip coffee is 96 mg (USDA FoodData Central and dataset values), so black tea is about 49% of that coffee's caffeine on a per-240 ml basis in the dataset. L-theanine is an amino acid.
The heuristic can mislead because it ignores serving size, leaf form (matcha 70 mg per 240 ml in the dataset), and beverage-specific serving sizes like energy drinks or cold brew that are much stronger; check our matcha guide and cold brew guide when substituting. When precision matters—sleep timing, pregnancy limits, or stacking multiple drinks—do the math with dataset numbers or plug items into our caffeine half-life calculator and last cup before bed tool to estimate residual caffeine at bedtime.
Bottom line
On a per-240 ml-cup basis the dataset lists black tea as 47 mg and green tea as 28 mg (USDA FoodData Central). Use a first-order elimination model with a population-average half-life of 5.7 hours to estimate residual caffeine: remaining mg = dose × 0.5^(hours/5.7) (the 5.7-hour half-life is the decay model we use, see Drake et al.).
The FDA guidance for healthy adults is about 400 mg/day, so count your drinks: for example, nine 240 ml cups of black tea (9 × 47 mg = 423 mg) would exceed the FDA 400 mg/day benchmark (FDA and USDA FoodData Central). If you need precise totals or bedtime timing, use our tools—caffeine half-life calculator, latest cup before bed, and caffeine comparison—and consult pregnancy and adolescent guidance found in our pregnancy guide and teenager safety guide.
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.
Can tea alone push me over the FDA daily caffeine limit?
Yes — nine 240 ml cups of black tea (9 × 47 mg = 423 mg) would exceed the FDA 400 mg/day guideline (FDA, USDA FoodData Central). Most people would need many cups or stronger drinks to hit that level.