A tea name is a useful clue to flavour. It is a poor measuring instrument for caffeine. Black, green, white and oolong teas all come from Camellia sinensis; the amount in your cup also depends on the product, the quantity you brew and the way you make it. Start with the serving size whenever you compare numbers.
How much caffeine is in a cup?
The FDA lists typical figures of 37 mg for green tea and 71 mg for black tea in 12 US fluid ounces (about 355 ml). These are category reference figures, not test results for every tea on a shelf. A small tasting cup and a travel mug should not both be counted as an unspecified “cup”. Source: FDA beverage table.
In a laboratory study of 20 commercial tea products, Chin and colleagues found 14–61 mg per serving across the white, green and black teas tested. Those servings were 6 or 8 ounces, and the researchers found no clear caffeine ordering by tea type within that sample. That is a measured range from one study, not a universal minimum and maximum. Source: Chin et al., 2008.
| Tea | Reference | How to read it |
|---|---|---|
| Green | 37 mg / 355 ml | FDA typical figure; individual products vary. |
| Black | 71 mg / 355 ml | FDA typical figure; not a fixed value for every black tea. |
| White, green and black | 14–61 mg / 6 or 8 oz | Observed range in the 2008 study, with mixed serving sizes. |
| Oolong | Contains caffeine | No single figure assigned here; use product-specific data when available. |
| Matcha | Contains caffeine | Ask for the amount per gram of powder and the grams in your serving. |
| Herbal blends | Ingredient-dependent | Check the whole ingredient list and the maker’s caffeine statement. |
The entries deliberately do not form a strongest-to-weakest ranking. Where a reliable number for the actual product is missing, “contains caffeine” is more useful than a precise-looking guess.
The four details worth writing down
If you want to compare two brews, keep a short record. You do not need specialist equipment: a kitchen scale, a timer and a mug whose capacity you know are enough to make your recipe repeatable.
- The tea: record the product name, not just “green”.
- The dry quantity: use grams, or the number of bags and their stated weight. A teaspoon of small broken leaf and a teaspoon of large twisted leaf are different measures.
- The water: record millilitres and starting temperature.
- The time: note when you remove the leaf, plus any later infusions.
The Chin study found that steeping time affected caffeine concentration. It did not establish a kitchen formula that turns minutes into milligrams. Your recipe record is a way to describe the brew accurately; it is not a caffeine test. Use our brewing basics for flavour starting points.
Green, white and oolong are not caffeine categories
Choose a green tea for its grassy or savoury character, a white tea for the particular leaf’s floral notes, or an oolong for its aroma and roast. Do not assume their names put them on a reliable caffeine ladder. Even a pale infusion can contain caffeine.
Ito En’s ingredient guidance identifies green, oolong and black tea as caffeine-containing teas, while distinguishing rooibos and grain infusions. That distinction is useful when stocking a cupboard; it does not supply a number for your homemade oolong. Source: Ito En’s caffeine FAQ.
Our Energy page compares caffeinated styles by taste and preparation. The Focus page explores shaded greens. The page names organise tea choices; they are not promised outcomes.
Matcha needs a different serving question
With matcha, the powder stays in the drink. “One bowl” is therefore incomplete information: how much powder went into it? Ippodo explicitly lists matcha, gyokuro, sencha and bancha among its teas that contain caffeine. Source: Ippodo’s caffeine guidance.
For a labelled product, multiply caffeine per gram by the grams used. If a maker states a value for a prepared serving, check that the serving matches your recipe. Adding more water or milk to the same prepared matcha changes its concentration and flavour, but it does not change how much powder you put into the drink. A larger latte is not automatically a larger matcha dose.
Caffeine-free and decaffeinated mean different things
A pure rooibos infusion is a different ingredient from tea leaf that has been decaffeinated. A blend can mix ingredients from both groups, so the large flavour name on the front of the packet is not enough. “Mint” could describe mint alone or mint mixed with green tea.
In the Chin study, the decaffeinated teas still contained caffeine, at less than 12 mg per tested serving; caffeine was not detected in the tested herbal varieties. Neither finding applies automatically to every product sold under those labels. For a caffeine-free choice, look for an explicit maker statement and read the ingredients.
Likewise, a quick rinse is not evidence that a tea has become caffeine-free. If the caffeine status is central to your choice, choose a product with that status stated rather than trying to infer it from a brewing trick.
Put the information to work
Before buying, ask: is the number per 100 ml, per bottle, per gram or per prepared serving? For a bottled drink labelled per 100 ml, multiply by the bottle volume divided by 100. For a brewed tea, keep the maker’s recipe beside its number. Do not compare dry-leaf measurements directly with a finished drink.
Then choose the cup you actually enjoy. A precise-looking table should not overrule a clear ingredient list or a transparent product specification. To turn those choices into a small, practical cupboard, read our morning, afternoon and evening tea rotation.
Sources and editorial scope
Sources checked 25 September 2026: the FDA’s beverage reference table, Chin et al.’s original analytical study, and the ingredient guidance from Ippodo and Ito En linked above. Figures are presented with their original serving context. This guide covers caffeine content and preparation; it does not set a personal intake target.
Frequently asked questions
Does green tea always have less caffeine than black tea?
No. Typical category figures are not a reliable ranking of individual products. Check the product, serving size and brewing method before comparing numbers.
How much caffeine is in oolong?
Oolong contains caffeine, but there is no single amount for every oolong and recipe. Use a maker’s measurement with its serving details when one is available.
Is white tea caffeine-free?
No. White tea comes from the tea plant and contains caffeine. A pale colour or delicate flavour does not establish a low caffeine content.
Does adding milk change the caffeine amount?
Adding milk to the same prepared tea changes the drink’s volume and concentration. It does not remove the caffeine already in that tea.
Is decaffeinated tea the same as caffeine-free herbal tea?
No. Decaffeinated tea can still contain caffeine. Herbal blends depend on their ingredients; check for tea leaf and read the maker’s caffeine statement.
Can I calculate caffeine from steeping time?
Not reliably at home. Time is one brewing variable, but it is not a direct conversion to milligrams. Product-specific measurements are more informative than a universal per-minute rule.