Caffeine Half-life Calculator


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This page contains information about the biological half-life of caffeine.

What is the Half-Life of Caffeine?

The half-life of caffeine can be used to calculate how long coffee will affect you after you drink some. Knowing this can help you adjust your coffee intake in order to improve your sleep schedule, or help you determine how often you should drink caffeine in order to maintain a stable level of caffeine through the day.

The biological half-life of caffeine in typical adults is between 5 to 6 hours. This means if you had 100 grams of caffeine, you would have around 50 grams after 5 hours.

Caffeine Calculator

This is a tool to calculate approximately how much caffeine you'll have in your blood based on your intake.

Please note that this is just informative and should not be used for medical or health purposes.

The format of each line is the time you had Caffeine and the amount in milligrams.





Results...

Is it bad to drink coffee on an empty stomach?

While coffee is a beloved morning ritual for many, drinking it on an empty stomach may not be the best idea. The high caffeine content can stimulate the production of stomach acid, potentially leading to heartburn or indigestion.

Coffee also contains natural compounds that can stimulate the secretion of gastrin, a hormone that aids in digestion. However, when consumed on an empty stomach, this can cause an overproduction of stomach acid, leading to discomfort.

Moreover, coffee can interfere with our body's ability to absorb certain nutrients, such as iron, due to its high tannin content. This effect is amplified when coffee is consumed without any accompanying food.

Therefore, while a cup of coffee can be a great way to kickstart your day, it's advisable to have it after a meal or alongside some food. This can help mitigate potential adverse effects and ensure you reap the many benefits of coffee without the drawbacks.

Recommended daily caffeine intake for adults

Understanding the amount of caffeine that is safe for daily consumption is crucial for maintaining a healthy lifestyle. While our Caffeine Half-life Calculator provides an excellent tool for tracking the amount of caffeine in your body over time, it's equally important to know the recommended daily intake of caffeine for adults.

The Food and Drug Administration (FDA) suggests a maximum daily caffeine intake of 400 milligrams for most adults. This is roughly the amount of caffeine found in four cups of brewed coffee. However, it's important to note that individual tolerance to caffeine can vary. Some people may experience side effects with lower amounts.

Remember, caffeine is not just in coffee or energy drinks. It's also found in tea, chocolate, some medications, and various foods. Therefore, it's essential to consider all sources of caffeine in your diet when calculating your daily intake.

It's important to note that while caffeine can have positive effects such as increased alertness and improved concentration, excessive consumption can lead to side effects. These can include insomnia, nervousness, restlessness, stomach upset, fast heartbeat, and muscle tremors. Pregnant women, people with certain health conditions, and those who are sensitive to caffeine may need to consume less.

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Citation

If you find this work useful, please cite it as:
@article{yaltirakliwikicaffeinehalflife,
  title   = "Caffeine Half-life Calculator",
  author  = "Yaltirakli, Gokberk",
  journal = "gkbrk.com",
  year    = "2024",
  url     = "https://www.gkbrk.com/wiki/caffeine-halflife/"
}
Not using BibTeX? Click here for more citation styles.
IEEE Citation
Gokberk Yaltirakli, "Caffeine Half-life Calculator", October, 2024. [Online]. Available: https://www.gkbrk.com/wiki/caffeine-halflife/. [Accessed Oct. 26, 2024].
APA Style
Yaltirakli, G. (2024, October 26). Caffeine Half-life Calculator. https://www.gkbrk.com/wiki/caffeine-halflife/
Bluebook Style
Gokberk Yaltirakli, Caffeine Half-life Calculator, GKBRK.COM (Oct. 26, 2024), https://www.gkbrk.com/wiki/caffeine-halflife/

Comments

Comment by Al
2024-10-02 at 16:57
Spam probability: 0.146%

You should add a line that shows the safe amount of mgs to have in your system at bedtime

Comment by Bob
2024-09-24 at 21:45
Spam probability: 0.239%

Correctness be darned, this is very fun and cool tool. Thanks for making.

Comment by Andreas
2024-08-22 at 14:45
Spam probability: 0.082%

Thanks to this I realized that I should definitely have my last coffee by around 13:00 because otherwise I'll sleep pretty poorly. Ever since then I started sleeping way better! Thank you! :)

Comment by s2bert
2024-01-28 at 20:27
Spam probability: 0.004%

RE: I think there's something off with your manual calculations. > "Say, for instance, somebody drinks something with 300 mg of caffeine. When they multiply the amount by 0.5, they should have 150 mg left > over the course of 5 hours. But, when that same amount is multiplied by 0.09, there are 27 mg of caffeine left in 1 hour. > So the formula, apparently, is: > 300*0.5=150mg/5 hrs. > 300*0.09= 27mg/hr. > Please, make this make sense." The half life varies by person between 1.5h and 9.5h. Let's say the half life is 5.5h (1.5+(9.5-1.5)/2) that means there's a reduction of 0.126 of the current amount each hour, or to put it another way 0.874 of the original value remains each hour. A quick check of 0.5 divided by 0.874 five times gives you around 0.980. So the numbers I've quoted are about right. Let's see how this tool stacks up. If I put 500mg at 00:00 that should expose the fraction used here. I see it's 440 after 1:03 (I can't get 1:00 using the mouse) 440/500 = 0.880 not quite 0.874 but not far off at all. I suspect 5.5h is the value used. For 0.874 it should proceed 437, 382, 333.81, 291.75, 254.99 Let's measure the chart some more and measure the time it reaches 291.75 Well, my 0.874 is a bit off by the 5th hour according to his calc. But using 0.885 gives 271.44, 272.11 is the chart value. So the factor the calc uses is closer to 0.885 Let's look at the JS code in the page and see if we can't find it: The code uses: Math.pow(.5, 1/5.7) Look familiar 0.5 being "half", 5.7 being the number of hours. Math.pow(.5, 1/5.7) = 0.88549827614566269708811843273963 What do we get for the value using that constant? Math.pow( 0.88549827614566269708811843273963, 5 ) x 500 = 272.21283878137388296978896025743 Let's look at the entry in the chart for 5h in after 500mg at 00:00 and we get: 05:00 - 272.21 mg Yup, so the calculator is using an exponential decay based on a 5.7h half life. It's correct. What can make a difference is when you choose to add the caffeine from subsequent intakes. Be careful of that.

Comment by Guest
2024-01-28 at 19:49
Spam probability: 0.316%

@JT-price, @S, The calculations are correct. Just ask Chat-GPT 4

Comment by S
2024-01-09 at 08:30
Spam probability: 0.045%

JT Price, His calculations are wrong, that's why it doesn't make sense. You'd want to multiply 0.9 not 0.09, as the caffeine degrades about 10% per hour (thus 50% in five hours).

Comment by highoncoffee
2023-11-29 at 21:55
Spam probability: 0.585%

this isn't helpful as i'm still extremely sensitive to caffeine in general

Comment by Proff
2023-11-15 at 13:41
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Good brews, everyone!

Comment by Guest
2023-11-13 at 02:28
Spam probability: 0.064%

Does the height, weight, sex etc... of the individual affect the half life? I couldn't imagine the half life of caffeine would be the same between a 6' 220lb male and 5' 140lb female?

Comment by JT Price
2023-10-30 at 02:16
Spam probability: 0.014%

I think there's something off with your manual calculations. Say, for instance, somebody drinks something with 300 mg of caffeine. When they multiply the amount by 0.5, they should have 150 mg left over the course of 5 hours. But, when that same amount is multiplied by 0.09, there are 27 mg of caffeine left in 1 hour. So the formula, apparently, is: 300*0.5=150mg/5 hrs. 300*0.09= 27mg/hr. Please, make this make sense.

Comment by tulio_ribeiro
2023-07-26 at 16:46
Spam probability: 0.158%

A lot of people don’t realize that caffeine is not the only substance that affects our body when we drink coffee. There is also paraxanthine, which is a metabolite of caffeine that has a similar half-life and similar effects. Paraxanthine can increase lipolysis, which means it breaks down fat and releases fatty acids into the bloodstream. It can also enhance alertness, mood, and cognitive performance. So, even when the caffeine levels in your blood start to drop, the paraxanthine levels are still high and keep you stimulated. That’s why the effects of coffee can last much longer than you think.

Comment by icouldntresist
2023-07-26 at 15:58
Spam probability: 0.146%

I've actually been cutting out caffeine after listening to Michael Pollan talk about drugs and society on NPR. Turns out the half life is typically long enough that using caffeine every day long term will lead to cognitive decline because of sleep deprivation. It's good for an occasional boost, but you're really burning the candle at both ends.

Comment by K-man
2023-07-26 at 15:52
Spam probability: 0.506%

People can have wildly different rates in which caffeine is metabolized. Depends on how much CYP1A2 enzyme you produce.

Comment by Max
2023-05-26 at 02:25
Spam probability: 0.538%

No wonder i cant sleep, im consuming in total 500mg of caffine, and that shit last for agesss

Comment by Sam
2023-05-10 at 07:02
Spam probability: 0.666%

Very helpful thanks

Comment by Noah
2023-03-26 at 23:15
Spam probability: 1.416%

Excellent tool :)

Comment by G-Man
2023-03-21 at 15:58
Spam probability: 0.79%

This is Awesome!

Comment by Charles
2022-10-12 at 06:40
Spam probability: 0.201%

At what amount does the body just flush caffeine out?

Comment by Guest
2022-09-26 at 04:57
Spam probability: 0.481%

Awesome! I wish it was 48 hours at least.

Comment by Guest
2022-09-16 at 01:00
Spam probability: 0.036%

Could you make a calculator that plots this across a whole week by letting you put in different times and amounts each day of the week?

Comment by totally spam
2022-08-27 at 00:21
Spam probability: 1.462%

cool stuff

Comment by Stan Lee
2022-08-24 at 01:48
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Excelsior!

Comment by COFFEE MACHINE
2022-08-12 at 19:28
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C4FFE1NE ADDICT3D S1NGL3S 1N Y0UR 4RE4!!!!! CL1CK H3R3 T0 OV3RD0SE 0N C4FF3INE N0W!!!!!! L1M1T3D EDITI0N D0 N0T MI$$!!111!!!!!!!

Comment by admin
2022-04-28 at 14:17
Spam probability: 0.028%

Hey @Steve, the calculator is for the weight of the caffeine. You should enter the weight of the caffeine you consumed in milligrams. Thinking about it though, it should be okay to enter the weight of coffee as well. I don't think the calculation will be thrown off too much, but the end result will be in coffee-weight instead of in caffeine-weight. If you know the caffeine content of your drinks this should be easy to calculate as well.

Comment by Steve
2022-04-28 at 10:55
Spam probability: 0.149%

So cool. But is this for weight of coffee rather than caffeine?

Comment by Guest
2022-03-09 at 19:17
Spam probability: 1.284%

Perfect

Comment by Nicolas
2022-02-11 at 00:24
Spam probability: 0.128%

Hi there says "if you had 100gr of cafeine, shouldn't this be mg? Cheers

Comment by Guest
2022-01-28 at 13:43
Spam probability: 0.78%

I want high spam probability, I'm a robot, Beep-boop.

Comment by Henry
2022-01-12 at 19:28
Spam probability: 1.85%

Great

Comment by Tobias
2022-01-12 at 10:05
Spam probability: 0.029%

Hi, great calculator! Was just sitting here at the breakfast table thinking about this while drinking my coffee. Would you mind share the code on your GitHub? Would be nice to have a look at it

Comment by admin
2022-01-07 at 11:32
Spam probability: 0.125%

Hi @Guest, The tool does not calculate multiple days, but you can still calculate what happens for your daughter with some manual steps. First, enter nothing other than the 325mg of caffeine, for example at 19:00 in the evening. Going to the end of the plot, you can see that this leaves her with 47mg of caffeine at 10:55 in the morning. To simulate what happens in the next day, just edit the input field and enter `10:55 47`. You can see that with the leftover caffeine from the previous day, the next day now starts with 49mg instead of the previous 47. But this is not a snowballing accumulation, if you modify the input again to change the 47 to 49, you will see that the next morning the value stays at 49 again. Unless you exceed a certain amount, you shouldn't get caffeine accumulating in you body until infinity. The thing to worry about in this case is the amount she takes at once. The recommended maximum amount of caffeine in adults is around 300-400 mg as far as I know. She shouldn't be drinking any coffee/tea/coke etc during the day.

Comment by Guest
2022-01-06 at 22:14
Spam probability: 0.038%

This is a great tool I'm going to show my daughter who has started using pre-workout powder before her evening workout. Could it be expanded to show levels over multiple days? This powder she is using has 325mg of caffeine and using it daily, the caffeine in her body must be accumulating.

Comment by former overcaffeinated guy
2021-12-02 at 02:00
Spam probability: 0.931%

nice, thanks

Comment by admin
2021-12-01 at 02:39
Spam probability: 0.006%

Hi everyone! I fixed some problems with the calculator, so the results should be more accurate now. I hadn't touched the calculator in a long time, I cleaned up the internals and made it easier to do updates and fixes in the future. I am working on an input format that is easier to use. I'd appreciate any feedback or improvements regarding the tool. Feel free to discuss tips and tricks in the comments.

Comment by Ben
2021-10-12 at 21:33
Spam probability: 0.039%

Thanks for making this! Found out I basically have the equivelent of a whole cup of coffee in me by the time I'm trying to go to bed! Probably need to readjust my habits...

Comment by Guest
2021-09-05 at 11:15
Spam probability: 0.035%

This is great! Would maybe need a caffeine half time input somewhere, that changes a lot from person to person.

Comment by Chris
2021-08-20 at 18:48
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Anyone know what a "very small amount" means when the body disposes of it? I should be good to sleep if the calculator says 23mg at bed time right?

Comment by Guest
2021-08-08 at 19:02
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Oh no, now I'm a little worried at how I'm able to sleep after closing shifts with so much caffeine in my system.

Comment by Liam
2021-07-29 at 02:22
Spam probability: 0.133%

Thank you for this Gokberk, this is excellent. I do have a question - The calculator seems to be working off a 7-8 hour caffeine half-life but as you stated above, the half-life for typical adults is 5-6 hours. Have you factored in absorbtion time? Could you clarify? Cheers, Liam

Comment by Guest
2021-07-28 at 20:51
Spam probability: 0.678%

Great visualization. So easy to use.

Comment by Eric Poulin
2021-05-18 at 21:01
Spam probability: 0.491%

This tool is great. I've been looking for this!

Comment by Adam
2021-04-21 at 19:00
Spam probability: 0.04%

Great tool, thank you. I think average users would benefit from a more guided input format, but that might not be worth your time.

Comment by Roden
2021-04-14 at 13:47
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Absolutely love this website! Makes me think about my consumtion

Comment by admin
2021-03-10 at 10:32
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Hey Tim! I'm glad you're enjoying it. If you have any problems, errors or recommendations; feel free to comment about them or send me an email.

Comment by Tim
2021-03-09 at 20:02
Spam probability: 0.94%

This is an awesome website, I love it!

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