how can i calculate how much caffeine is in a brew of 3 teabags of green tea and 1 teabag of earl grey in 24 cups of water? I'm trying to reduce the caffeine content.

  • this depends highly on exactly what tea and exactly how you brewed it, so all we can give you is a range (and without lab equipment, that's about how accurate you will get it).
    – Esther
    May 31, 2023 at 20:27
  • You didn’t ask specifically about reducing caffeine, and I think there’s another question about that on here. From what I remember: caffeine comes out early in steeping, so you let it sit for 30?60?seconds or so, dump the water, then brew again. As you’re reusing the bags, each subsequent brew should have less caffeine
    – Joe
    Jun 1, 2023 at 13:17

1 Answer 1


You won't be able to directly measure the caffeine content without lab equipment. You can use estimates, but the caffeine content of tea varies between different varieties, and varies by the preparation method (time to steep, temperature).

For example, this BBC Good Food guide to your question says:

An average cup of black tea with milk contains around 47mg of caffeine.

Green tea contains less caffeine than black tea, with on average 33mg per cup.

This Twinings page about caffeine in green tea says:

Twinings green tea contains around 30-40mg of caffeine per cup, based on 200ml of water being used.

These are both British references, so will be based on a cup of tea made by steeping one teabag in a mug of near-boiling water for a few minutes. If you search online you will find caffeine ranges for other preparation methods.

If you are interested in reducing your caffeine consumption, the important fact for you is that green tea contains a little less than black (so drinking more green and less Earl Grey will reduce caffeine intake), and of course you can dilute the tea so that you are consuming less of it (but this will also dilute the flavour). The simplest thing to do would be to buy decaffeinated tea.

  • interesting, all I've ever seen is that green has more caffeine than black, and then I saw this site that basically says "it depends"
    – Esther
    May 31, 2023 at 20:35
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    I'm trying to stay hydrated at work- it's not easy in a Cardiac ICU working 12 hour shifts basically w/o breaks. Yes, I will be buying decaf tea, but I have 2 boxes (160 count each) of Bigelow green teabags. I use Red Rose Earl Grey teabags. I brew the tea in a 12 cup coffee maker and then reuse the bags for another 12 cups, so I'm assuming it's pretty watered down and the caffeine content should be lower. Thanks for your help!
    – NurseMom
    May 31, 2023 at 21:00
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    @NurseMom cooking.stackexchange.com/questions/102939/…
    – Esther
    May 31, 2023 at 21:30
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    Yes, I do drink water, but I get tired of just drinking that all day.
    – NurseMom
    May 31, 2023 at 21:31
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    Also, tip from another caffeine-sensitive: carbonated mineral water is a good way to get away from "water boredom", as is water mixed with a small amount of shrub (as in, vinegar/fruit concentrate).
    – FuzzyChef
    Jun 2, 2023 at 17:49

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