How We Measured Caffeine in Our Teas

We analyzed 11 teas using high-performance liquid chromatography (HPLC) to better understand caffeine recovery through repeated hot-water extraction.

Here’s how we measured it, what we found, and what those numbers mean.

How We Measured It

  • Tea Samples

    We analyzed 11 teas. Nine samples used 3g of tea; two oolong samples used 5g.

  • Hot-Water Extraction

    Each sample underwent three consecutive 15-minute hot-water extractions, using 150mL of water per round.

  • HPLC Analysis

    We measured caffeine concentration in each extract and calculated cumulative recovery across all three rounds.

This research was conducted at the Department of Tea Science, College of Agriculture and Biotechnology, Zhejiang University, China.

The Results

Caffeine Recovered Across Three Extended Extractions

These figures reflect caffeine recovered under extended laboratory extraction conditions, not a typical cup of tea.

Cumulative caffeine recovered per tea across three extended hot-water extractions, with espresso equivalents.
Tea Tea used Caffeine recovered Espresso equivalent
Emerald Dew 3g 96.66mg ≈1.5 espresso shots
Pine & Cypress Sheng 3g 87.86mg ≈1.4 espresso shots
Pearl Yellow Tea 3g 87.45mg ≈1.4 espresso shots
Dragon Well 3g 87.08mg ≈1.4 espresso shots
Shou Pu'er 2015 3g 85.69mg ≈1.4 espresso shots
2024 White Peony 3g 83.49mg ≈1.3 espresso shots
Baojing Golden Green 3g 82.10mg ≈1.3 espresso shots
2019 White Peony 3g 80.38mg ≈1.3 espresso shots
Floral Black Tea 3g 78.26mg ≈1.2 espresso shots
Floral Zhangping Shuixian 5g 64.02mg ≈1.0 espresso shot
Tieguanyin 5g 56.14mg ≈0.9 espresso shots

Zhangping Shuixian and Tieguanyin were tested using 5g of tea; all other samples used 3g. Espresso equivalents are calculated using approximately 63mg of caffeine per shot.

Why compare tea with espresso?

We use espresso as a familiar point of reference to help make caffeine quantities easier to picture. For this comparison, one shot is treated as approximately 63mg of caffeine.

It’s a comparison of measured caffeine quantities, not a prediction of how stimulating a tea will feel.

Not a Typical Cup of Tea

Our results reflect caffeine recovered through three extended hot-water extractions, rather than a single everyday serving.

Why Brewing Matters

Tea quantity, temperature, steeping time, leaf form and number of infusions all affect how much caffeine enters your cup.

Frequently Asked Questions

Does green tea always have less caffeine than black tea?

Not necessarily! Tea type alone isn’t a reliable way to predict caffeine content.

In our testing, Emerald Dew green tea yielded approximately 97mg of caffeine from 3g of leaves, while Floral Black Tea yielded around 78mg from the same amount.

That’s a good reminder that green tea isn’t automatically lower in caffeine than black tea. The specific tea matters more than the category alone.

Does aged tea contain less caffeine?

Not necessarily. Aging doesn’t automatically mean less caffeine.

In our testing, 2019 White Peony yielded approximately 80mg of caffeine from 3g of leaves, compared with 83mg from the 2024 White Peony.

The results were relatively close, despite the difference in age. However, because these were different tea samples, we can’t attribute the difference to aging alone.

Is this how much caffeine I'll drink from one cup?

No. These numbers represent the total caffeine recovered through three extended hot-water extractions, not a typical cup of tea.

In everyday brewing, the amount of caffeine you consume depends on how much tea you use, water temperature, steeping time, and how many infusions you drink.

Think of these results as a way to compare our teas under laboratory conditions, rather than a prediction of your daily caffeine intake.

Why compare tea with espresso?

Espresso gives us a familiar reference point for understanding caffeine quantities.

For this comparison, we use approximately 63mg of caffeine per espresso shot. For example, the 87mg recovered from 3g of Dragon Well is roughly equivalent to 1.4 espresso shots.

But that doesn’t mean drinking Dragon Well will feel the same as drinking 1.4 shots of espresso.

We’re comparing measured caffeine quantities, not how stimulating a tea might feel.