Tea & Me
Teawares

Caffeine in Chinese Tea (茶与咖啡因): What Actually Changes the Number in Your Cup

The Chart You’ve Seen Is Mostly Wrong

Every tea shop has one: a tidy table saying white tea has 15mg of caffeine, green 30mg, oolong 40mg, black 60mg. It’s reassuring and it’s close to useless. The category on the label tells you far less about the caffeine in your cup than how much leaf you used, how hot the water was, and how long you let it sit.

The good news is that the three things that matter are exactly the three things you already control.

Ink wash illustration of a gaiwan beside a small cup of amber tea and a timer, steam rising in soft brushstrokes

What the Numbers Actually Say

Start with the FDA’s figures, which are per 12-fluid-ounce serving: regular brewed coffee runs 113–247 mg, black tea about 71 mg, green tea about 37 mg. The FDA considers 400 mg a day the point below which healthy adults generally see no negative effects.

So tea sits well below coffee. That part of the folk wisdom holds, and the reason is mundane: a cup of coffee is made with 10 grams or more of finely ground beans, while most cups of tea use under 5 grams of whole leaf. Gram for gram, dry tea leaf is often more caffeinated than a coffee bean. You just use much less of it, and whole leaf gives water less surface area to work with.

Where the folk wisdom falls apart is the ranking within tea. A 2025 HPLC study brewed five tea types under identical conditions — 2g of leaf in 200ml at 80°C for two minutes — and measured this:

Tea typeCaffeine (mg/200ml)L-theanine (mg/200ml)
Black (red)14 ± 1.012 ± 2.8
Yellow13.8 ± 0.24 ± 1.1
Green11 ± 2.113 ± 2.5
White5.8 ± 0.71.8 ± 0.4
Oolong4 ± 1.62.1 ± 0.5

Source: Determination of L-Theanine and Caffeine Contents in Tea Infusions, 2025.

Two things jump out. First, every number is far below the shop chart — because a gentle two-minute steep at 80°C is nothing like the five-minute boiling-water steep those charts assume. Second, the spread between the top and bottom is about 10mg. That’s a third of a square of dark chocolate. The category barely matters.

The Three Dials That Do Matter

Time is the big one. In that same study, yellow tea went from 13.8 mg to 53 mg per 200ml when the steep went from 2 minutes at 80°C to 10 minutes at 100°C. That’s a four-fold swing from one leaf, one grade, one cup. Nothing about tea type comes close to that.

Temperature matters, but less than you’d think. Across most of the teas tested, the jump from 80°C to 100°C wasn’t statistically significant. The exception was oolong, which went from 4 mg to 14 mg — tightly rolled leaf needs heat to open up before it gives anything away, caffeine included.

Leaf quantity is linear and obvious. Double the leaf, roughly double the caffeine. This is the dial people forget they’re turning when they switch from a Western mug to gongfu.

The Bud Problem

Here’s the counterintuitive one: the caffeine in a tea plant is concentrated in the buds and youngest leaves, and drops as the leaf matures. It’s a defense chemical, and the plant protects its tender growth.

Which means the teas marketed as the most delicate are often the most caffeinated leaf in your cabinet. Bai Hao Yinzhen is pure bud. So is Jin Jun Mei . Meanwhile Shou Mei , made from larger, later leaves, carries noticeably less — even though both are “white tea” and the chart gives them the same number.

If you’re picking a tea by caffeine, read the grade, not the category. Bud-heavy and early-spring means more; large-leaf and late-harvest means less. Our guide to reading a tea listing covers the vocabulary.

The Rinse Myth

You will be told that a quick 15- or 30-second rinse washes the caffeine out and leaves the flavor. It does not.

Hicks, Hsieh and Bell measured this at Auburn University in 1996 using HPLC, and the result has been replicated since: a 30-second initial wash leaves roughly 91% of the caffeine in the leaf. Caffeine comes out gradually over the whole infusion, not in a burst at the start. You’ve thrown away a perfectly good first cup and changed almost nothing.

Rinse your pu-erh and your tightly rolled oolongs if you like — it wakes the leaf up and it’s good practice. Just don’t do it for the caffeine.

Two related corrections while we’re here. Decaffeinated tea isn’t caffeine-free; caffeine is native to Camellia sinensis and can’t be removed completely. And only herbal tisanes — chrysanthemum, chamomile, rooibos — are genuinely caffeine-free, because they aren’t tea at all.

The Evening Playbook

Everything above collapses into a few habits.

If you want…Do this
Less caffeine, same teaCut the steep time first, then the leaf. Time is the strongest lever.
An evening cupPick a mature-leaf tea — Shou Mei, an aged shou pu-erh, a roasted Shuixian — and steep it short.
To spread the dose outBrew gongfu style . More leaf total, but split across many short infusions, with the first carrying the most.
Flavor without the hitCold brew it. Cold water extracts caffeine poorly and amino acids well.
Genuinely zero caffeineDrink a tisane. There’s no tea that gets you there.

One last thing worth knowing: tea also contains L-theanine, an amino acid that shows up in the table above — green and black tea carried 12–13 mg per 200ml in that study. Theanine moderates how caffeine lands, which is why a strong cup of tea tends to feel steadier than the equivalent caffeine from coffee. The two arrive together, and the same gentle steep that keeps the caffeine down keeps the theanine with it.

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