A Tea Addict's Journal


August 10, 2008 · 12 Comments

I sometimes wonder how much caffeine I actually drink everyday. I normally only drink one sitting of tea a day, using a smallish (100ml or less) pot, and filling it anywhere between 1/4 to 1/2 full. I will drink it until it tastes like nothing other than sweet water, and that could be anywhere from 10-30 infusions.

The normal amount of caffeine in a cup of tea varies wildly, since how you brew and what you brew makes a huge difference in the amount of caffeine you get. So they say the average is 50mg of caffeine in a cup of 5oz tea…. which doesn’t really mean anything to me, since I have no idea how they actually arrive at such numbers, and how that compares with how I brew mine. I drink far more than 5oz of tea, obviously, but it seems to me that unless you’re comparing weight of the leaves used per ounce of fluid, the comparison is almost meaningless.

Is there a way to test for caffeine? This is, of course, purely out of curiosity, but it’s nevertheless something that I am interested in knowing, if nothing else, because other people ask me all the time…. “which tea has less caffeine?”

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12 responses so far ↓

  • Anonymous // August 10, 2008 at 11:16 am | Reply

    I often wonder about my own caffeine intake. Cha Dao blog had a nice
    article on this matter a few months back:


    That may help answer a few of your questions. I enjoy this article
    because it appears to be based on a bit more than the typical (and often
    misleading) word of mouth.

  • djn7304 // August 10, 2008 at 12:15 pm | Reply

    A quick Google search comes up with several home caffeine test kits in the works, but I wasn’t able to find one currently for sale. I’ve found large amounts of caffeine tend to give me a headache. Kind of ironic since Excedrin contains caffeine and is supposed to relieve headaches.

  • djn7304 // August 10, 2008 at 2:13 pm | Reply

    Perkin-Elmer is a scientific supply company. They have a “caffeine test-kit” available for $27 US, but don’t supply any additional information about it.


  • Dogma_l // August 10, 2008 at 9:22 pm | Reply

    Having had this discussion with lots of people, I’ve decided that the only practical approach is to estimate amount of dry leaf used per day, and assume that folks like us steep out (and drink in) essentially all the caffeine. The range of caffeine concentrations in dry leaf is narrow enough for a useful approximation. I usually figure about 2% to accommodate rinsing and other losses. So a solo round of gongfu at 4 g plus a mug of EBT at about 5 g is about 200 mg caffeine, plus or minus.


  • MarshalN // August 10, 2008 at 9:30 pm | Reply

    Dogma: One can always count on you for quick and useful info 🙂

    Indeed, I think we all steep our teas out to having zero caffeine left, for all intents and purposes, while most of these lab estimates do not account for the way we drink tea, so those numbers are, by and large, rather useless…

  • Anonymous // August 11, 2008 at 2:08 pm | Reply

    Marshaln: The solubility of caffeine is quite high: 670mg/ml at 100C

    I think it is reasonable to expect the vast majority of the caffeine in a given amount of tea to be extracted by either gongfu, or brown betty.

    So Dogma’s dry weight method should still hold.

  • lewperin // August 11, 2008 at 4:37 pm | Reply

    I’m sure Dogma’s right that we stingy steepers eventually get virtually all the caffeine in the leaves down our gullets.

    But I’m far less confident that “The range of caffeine concentrations in dry leaf is narrow enough for a useful approximation”.

    Nigel Melican has written a lot about caffeine in tea, and in my book he’s authoritative. In this article he says the amount of caffeine in dried tea leaves can vary widely:

    Thus tea derived from older leaf, China type seedling bush, under-fertilized husbandry and in autumn season will naturally be lowest in caffeine. Georgian and Turkish tea falls into this category: expect only 1 to 1.5% caffeine in them, compared with the usual 3% in retail teas. Tea from well-fertilized fast-growing young tips of African clonal tea can often have 5-6% caffeine.

  • MarshalN // August 11, 2008 at 4:39 pm | Reply

    Point well taken Lew, but could it be that for the kind of teas we drink normally, the range is not quite as wide?

  • Dogma_l // August 11, 2008 at 10:20 pm | Reply

    My point exactly. The higher levels of caffeine in commercial tea are there to satisfy a market need, one that overlaps only somewhat with what most of us would consider flavor. I’m guessing that most teas typically subject to gongfu – or, more generally, imbibed by the readers of this excellent blog – fall within a narrower range: say 2-3.5% for one standard deviation, or something like that. Maybe Nigel can elaborate.

    If a two- or even three-fold range seems broad, bear in mind that most sensory reactions scale sub-linearly with stimulus once a detection threshold is reached: twice as much flavorant doesn’t make twice as much flavor. Physiological actives are a bit different as, for example, they may be excreted and/or detoxified (in the liver, say) at a constant grams/hour rate, rather than a remaining percentage/unit time. The “high” or insomnia might scale with intake. But I doubt that most people would easily notice a 50% variation in caffeine consumption over a few hours unless they led an otherwise extremely consistent lifestyle.


  • lewperin // August 12, 2008 at 2:23 pm | Reply

    if you steep the tea in hot water for a few seconds and then throw out the water you would have removed about 80% of caffine.

    I was wondering how long it would take before someone would repeat that immortal nonsense. Vendors everywhere love to reassure their caffeine-shy prospects with it, and – glory be! – “Chah tea” appears to be a sell tea, too. Anyone who thinks the 80% story might be even partially true should read the same article I cited earlier in this thread.

  • MarshalN // August 12, 2008 at 2:42 pm | Reply

    Indeed, and I am going to delete the post because I don’t like people linking to vendors for no good reason on my blog.

  • nick7777 // October 5, 2008 at 4:03 pm | Reply

    I’ve seen caffeine test kits advertised, but no information on them as to how they work ? does it differentiate between a little caffeine and a lot? does anyone know of   a good practical caffeine test I cluld use in a resturante?

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