Tea Caffeine Estimator
Estimate the caffeine in your daily tea by type, cup size, and cups per day, compared to the FDA 400 mg guideline.
These are typical figures. Brewing time, water temperature, and leaf amount can swing the actual caffeine in a cup by a wide margin — this is a starting estimate, not a lab result.
How it works
Each tea type has a typical caffeine figure per 250 ml cup, based on published averages: black around 47 mg, oolong around 37 mg, green around 28 mg, white around 15 mg, and matcha around 70 mg since you drink the whole ground leaf instead of an infusion. Herbal blends and rooibos are naturally caffeine-free. The calculator scales that figure to your actual cup size, multiplies by how many cups you drink, and compares the daily total to the FDA's 400 mg guideline for healthy adults.
Worked example: three 250 ml cups of green tea a day works out to about 28 mg per cup and 84 mg total, roughly 21% of the daily guideline. Swap in matcha at the same volume and cup count and the total jumps to about 140 mg, since whisked matcha carries more caffeine per cup than a steeped infusion of the same leaf.
FAQ
Why is matcha higher in caffeine than green tea?
With steeped tea, the leaves get discarded and you only drink what dissolved into the water. With matcha, you drink the ground leaf itself, so you get everything in it. That is why the same plant produces a much stronger cup as matcha than as loose green tea.
Does steeping time change the caffeine amount?
Yes, meaningfully. A short 1 to 2 minute steep pulls out less caffeine than a full 5 minute steep of the same leaf and water. The figures here assume a typical steep for that tea type, so a rushed or extra-long brew will land somewhat below or above the estimate.
Is the 400 mg guideline right for everyone?
No. It is the FDA's general guidance for healthy adults, not a target to hit or a universal safe limit. Pregnant or nursing people, anyone sensitive to caffeine, and people on certain medications should use a lower threshold and check with a clinician rather than relying on this estimate.
Are herbal tea and rooibos really zero caffeine?
Genuine herbal infusions and rooibos come from plants other than the tea plant (Camellia sinensis) and contain no caffeine at all. The exception is anything blended with real tea leaves, matcha, or yerba mate, which will carry whatever caffeine those ingredients add.
For more, see caffeine in tea, how much is in each type, the best teas for sleep, and rooibos, the caffeine-free red tea explained.