Computing My Caffeine Habit

Strong black tea is my drug of choice. But I got fed up with caffeine addiction a few years back and started to limit my intake. Currently I’m at 1.5 litres every second day, which means that my system is used to going without caffeine for over 40 hours at a time — counted from afternoon tea on a Monday to morning tea on a Wednesday for instance. This regimen works out to an average daily intake of 190 milligrams of caffeine. Coffee has about 1.7 times the caffeine in strong black tea, which in turn has 2.7 times the caffeine in Coke. But I never have coffee and very rarely any caffeinated soda.

Dear Reader, what’s your caffeine habit like? Here are some figures:

Coke: ~100 mg caffeine per litre
Strong black tea: ~250 mg caffeine per litre
Coffee: ~425 mg caffeine per litre

(A litre is about 34.5 fluid ounces.)


  1. #1 Erin
    June 24, 2009

    I don’t know what these “litres” are, but I’ve been drinking at least three 8 oz. cups of coffee on the weekdays and about 12 oz. on the weekends.

    And don’t forget chocolate!

  2. #2 Martin R
    June 24, 2009

    Erin, assuming that 12 oz of coffee is for the entire weekend, you have an average daily intake of ~230 mg caffeine counted across a full week. If you have 12 oz daily on weekends, your daily intake is ~250 mg.

    The active substance in chocolate, theobromine, is chemically similar to caffeine but has a far weaker effect.

  3. #3 JohnV
    June 24, 2009

    Looks like I’m at about 140 mg per day during the week and anywhere from 0 to 230 mg per day on the weekend.

    In practical terms its two 24 oz (710 ml) bottles of caffeinated diet soda each day at work and maybe a 40 oz diet caffeinated soda from 7-11 on the weekends (one near here has a thing to add some flavored syrup to it, yummm lemon diet pepsi). I’ve managed to stick to caffeine free diet soda and water at home.

  4. #4 Dave S
    June 24, 2009

    Two ~12oz mugs + two 8 oz cups of drip coffee per work day, say 40 fluid oz per day, so using your numbers about ~500 mg/day.

  5. #5 Martin R
    June 24, 2009

    Dave, are your hands shaking? Are you gritting your teeth? (-;

  6. #6 Fargo
    June 24, 2009

    About a year and half ago I decided to quit caffeine. Since then I’ve slipped off the wagon a couple times, but never for more than a meal or two. The resulting withdrawal headache is enough to warn me away. The first week was an unending hell of headache, moodiness, and vague nausea.

    Previously I’d guess my intake would have averaged somewhere around 250mg a day or more.

  7. #7 cicely
    June 24, 2009

    Just here in the last three months, I’ve been drinking a 12oz. coffee on week-mornings (my job isn’t challenging, and falling asleep at the keyboard is a real danger); but to compensate, I’m drinking my sodas Unleaded. On weekends, the only caffeine I get is when we eat out, and there is no decaff soda at the pump.

  8. #8 Neuroskeptic
    June 24, 2009

    It depends how strong your coffee is. I drink about 500 ml of instant coffee per day, but I make it with about four times as much coffee as most people I know… so that’s about 800 mg I guess?

    When you’re serious about caffeine, water is just an unwanted dilutant.

  9. #9 ArchAsa
    June 24, 2009

    Around 9-9.30 a large cup of my (not) patented budget-latte (half a cup of milk heated in the microwave + three large teaspoons of nescafé + some hot water + sugar)

    Repeat at around 2 pm.

    No coffee after 5 pm or I have to stay up all night. Perhaps a cup of black tea if I work late.
    Only rooibos red tea (caffein-free) after 9 pm.

    The second cup of coffee is optional, the first one isn’t or I get serious withdrawal symptoms. I will check myself into rehab the moment my dissertation is finished.

  10. #10 Matt B.
    June 24, 2009

    I usually have a big cup of strong black coffee for breakfast (and nothing else).
    Then one or two cups in the afternoon.
    Which should be something around 200 mg per day.

    And I do get the withdrawal headache if I haven’t drunk enough caffeine two days in a row.

  11. #11 InkRose
    June 24, 2009

    Now, currently I’m not entirely sure of the amount of caffeine in the instant coffee we have at work. But I have 3 cups of it during the day, so let’s say for these purposes 450 ml of instant coffee a day, 5 days a week. I put more milk than average in my coffee. I guess I average 1-2 energy drinks a week on top of that. I don’t currently drink coffee on weekends, maybe 2-4 cups of green tea a month besides the work intake. This will probably change when I return to Finland.

    So, based on the wikipedia article on coffee, my current caffeine intake is somewhere around 240mg a day during the week, and a guesstimated 150mg daily (I seem to favour the flavour of things like Relentless on the energy drink front, and they seem to come mostly in 500ml cans/bottles) on weekends. That seems to amount to approximately 1500 mg a week, which does sound like a lot. Then again, in Finland I favour a fairly strong drip coffee over the instant stuff, which’ll mean a roughly 30% increase in my weekday intake when I return home, if I don’t make any other changes. Otoh, the energy drinks will probably be reduced then, so it may balance out in 5 weeks’ time.

  12. #12 Robert Sugg
    June 24, 2009

    ____My mug of choice is a ceramic, 500ml nominal (550-600 ml actual, about 18 oz.) beer mug – one of those standard, cheap, gray, microwave-safe, heat-retaining brutes. Something smaller would mean refill hassles. Something larger would be ridiculous. I stuff it with two teabags (usually oolong), steep for at LEAST five (5) minutes (often more), add sugar + lemon + lime (vitamin C !). In short, Scots-style. I have no idea of my caffeine dosage – I just try to only have one to two mugs per day.

  13. #13 Doug Alder
    June 24, 2009

    You have a problem with your ~ dosages. The amount of caffeine in coffee varies dramatically. How much you get depends on where the beans were grown, whether they are Robusta or Arabica beans (Arabica having ~ 50% of the caffeine of Robusta), how much they are roasted (the darker the roast the less caffeine) and how the coffee is brewed. The variables are too great for any definition of “average” to be meaningful.

    Having said that I have my own espresso machine and I only use dark locally roasted Arabica blends (my roaster is a friend and his store is only a few blocks from here so beans are never more than a few days old). I have 3 double espressos every day. Typical American style coffee (what you would get in a diner or making drip coffee at home with Maxwell House say, if following directions)has ~ 100mg of caffeine. However those commercial coffee blends have, until very recently, been almost exclusively consisted of light roasted Robusta beans – so the caffeine content is very high.

    Brewing espresso extracts every last bit out of the grounds so I’m going to take a wild guess here and say that because the arabica beans have ~ 50% of the caffeine of Robusta beans, and that dark roasted beans have even less caffeine then my double espressos are probably in the range of 100-150 mg caffeine each – so 300 to 450mg per day.

    I sleep very well thank you 🙂

  14. #14 Martin R
    June 25, 2009

    Robert, I also favour those half-litre mugs. When teabagging (hehe) I have recently taken to using two bags to match the amount of leaf I get when brewing with a spring-loaded wire mesh ball.

    I wonder why black tea has more caffeine than green! Is it just about how much of the compound that can escape the two types of leaf, the content per weight being the same?

  15. #15 Akhôrahil
    June 25, 2009

    The thing about green and black tea might not actually be true. Caffeine content in tea is a very complex thing. See for instance

    (Also, tea bags? I hope that’s only in the direst emergency!)

  16. #16 Jonathan Jarrett
    June 25, 2009

    I used to drink an awful lot of tea, but no coffee, and then one day at work I lost my temparature regulation, started having palpitations and the vertical hold on my vision went for a bit. So after that I calmed down some, and made sure to do periodic dry weeks. (I’m told that to really detox one needs a fortnight but I never make it long past the headaches stop.)

    However, the current job has a workplace routine of making good coffee at 11, and so I’ve been sucked back into things, and the dry week is long long overdue. Currently I’m on three mugs of tea in the morning, half a mug of coffee at 11, a mug of tea in the mid-afternoon, and following your figures and assuming a 300 ml mug, I think that brings me out at about 400 mg per day. And I ought to cut that down, really. I stress too much even without that help. Trouble is I like tea too much.

  17. #17 Martin R
    June 25, 2009

    *sings* “Cold turkeeeee has got meeeee on the run”

  18. #18 DianaGainer
    June 25, 2009

    Being subject to migraines periodically which mimic symptoms of strokes, I was once advised to cut out all caffeine. After about 3 months of daily migraines, I asked the doctor how months would it take for the caffeine withdrawal headache to stop. He advised to start up the caffeine intake again since most over-the-counter meds for migraine are chock full of caffeine anyway. I did so, in spades. I now make 8 to 10 cups of coffee a day, half with and half without caffeine, sometimes adding black or green tea, with or without caffeine, depending on the migraine situation. Fewer headaches as the Time of Life advances, fewer stroke-like symptoms, but the left hand has forgotten how to play the piano in the meantime. How annoying! Any claims that chocolate consumption will cure this?

  19. #19 Martin R
    June 25, 2009

    You’re… mixing tea into your coffee!?

  20. #20 BroccoliofDoom
    June 25, 2009

    Sounds like you guys are light weights. In my undergrad days I managed to consume 6-12 12oz can’s of coke (~200mg) in addition to a couple of pots of coffee, say a 1/2 to a full liter per day (200-400mg). Even that doesn’t include my NoDoz habit at the time. Average sleep per night was ~5-6 hours.

    Oddly enough now that I’m in graduate school I sleep less but consume less as well. Although, any idea how much caffeine is in a DoubleShot can? Because I go through four of those a day now! Average sleep for a weeknight is ~3 hours.

  21. #21 Martin R
    June 25, 2009

    There’s a Demon Lord in old-school Dungeons & Dragons who looks a bit like he should be named Broccoli of Doom. Only he’s known as Jubilex the Faceless Lord instead. My friend David once described him as “a pile of cauliflowers that spews slime”.

  22. #22 Tsu Dho Nihm
    June 25, 2009

    I drink herbal tea every now and then. It has about 5mg per mug.

  23. #23 Akhôrahil
    June 26, 2009

    It’s “Juiblex”.

    (It’s not like he’s the demon lord of celebrations. 🙂 )

  24. #24 RBH
    June 28, 2009

    I have to limit to <200 mg/day. Otherwise I start throwing premature atrial contractions. Kind of a strange feeling to go down to the fire station and wire myself up to the heart monitor in the medic to watch my own arrhythmia. 🙂

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