Caffeine is a key component in coffee…
and possibly the reason why many of us started drinking coffee.
Remember those canned coffee that was always within reach, and how they’d mysteriously vanish quickly closer to exam dates?
If you drink coffee daily, you would consume at least 365 cups of coffee in the past year.
That’s about 14.6g of caffeine per year.
But…what does ‘14.6g of caffeine’ really mean?
Is it good for you? or…will it kill you slowly?
In this article, that’s what we seek to answer.
tl:dr; Here are the findings:
How much caffeine is there in a cup of coffee?
How much caffeine in a Cafe Latte (specialty coffee)?
How many cups of coffee can I drink per day?
7 cups of espresso based coffee or 3 cups of drip coffee
We study the effects of caffeine in this article and answer some frequently asked questions on Caffeine and its effect on our health.
If you are here for answers to a particular question, click on the question below to jump straight to it:
- How many cups of coffee can I take per day?
- How much caffeine is there in espresso?
- How much caffeine is there in drip coffee?
- Does espresso or drip coffee have more caffeine content?
- Does caffeine really help to keep me awake? How?
- Why do I still feel sleepy after coffee?
- Will regular intake of caffeine harm me over the long term?
- Is it safe to drink coffee during pregnancy?
- Is it safe to drink coffee while breastfeeding?
(skip to section II)
- How much caffeine is there in a (raw) green coffee bean?
- Which has more caffeine – light roast coffee or dark roast coffee?
- Does the brewing method affect caffeine levels?
We are not doctors or scientists. Do not take our word as medical advice. Check with your doctor / physician instead. The answers provided here are merely derived from the work of many smart people in the academic world. We do our best to bring to you what we have found, there may be studies we missed out, or do not have access to. Let us know if you notice anything that should be included here!
Now, let’s jump right into the topic with some fundamentals:
What is Caffeine?
Caffeine is an alkaloid found in coffee beans (and tea, and chocolates…) It is also known as 1,3,7-trimethylxanthine.
*Interesting fact: when extracted, caffeine is a white powder (at room temperature). It doesn’t have any smell, but has a bitter taste.
It is easily the world’s favorite drug, with millions of people consuming it daily through various products like coffee, teas,
red bull energy drinks, chocolate, and more.
How much caffeine is there is my coffee?
- Espresso based specialty coffee has about 54.8 mg per 8 ounce cup
- Brewed Coffee (drip) has about 120 mg per 5 ounce cup
Before we have an army of angry coffee geeks breaking down our doors, here’s a disclaimer:
Why it is (almost) impossible to equate a fixed amount of caffeine to coffee, in general
Depending on the practices of the cafe, or coffee joint, or barista, your coffee could be prepared using a wide range of recipes.
Some cafes pull espressos.
Others swear by their ristrettos.
Some cafes serve an 8oz flat white and a 12oz cafe latte.
Not to mention, the wide range of drinks you can get from an espresso; long black, macchiato, cortado, etc, etc. 😕
I hope you are starting to get the picture.
It’s like trying to say that a bacon cheese sandwich has the same amount of calories as a chickpea sandwich.
Hence…we’ll be using averages for the following sections:
How many cups of coffee can I safely drink in a day?
How many cups of espresso-based coffee* can you safely drink in a day?
You can take about 7 cups of 8oz coffee each day, safely.
* espresso-based coffee refers to coffee made with an espresso or ristretto as the base. i.e. Long black, Cafe Latte, Flat White, Cappuccino, Cafe Mocha (which has slightly more caffeine due to the chocolate).
**do note that this number is derived from averages. The amount of caffeine in your coffee would depend on how your barista brews their coffee.
The number above are based on the following:
Many sources have stated that the safe level of caffeine consumption daily is ~400mg. [see references iii, iv,v,vi]
How much caffeine is there in an espresso?:
An espresso has about 54.8mg of caffeine per serving
Hence, you should drink only about 7 cups of espresso based coffee a day.
Many people might start getting side effects like headaches, anxiety, jitters, discomfort at about 5 cups per day. You should monitor the number of cups of coffee you drink before getting those uncomfortable side effects to determine how much you can drink per day.
Yea, we know. 1oz may not be your regular dose of espresso. Breath, coffee geeks, remember…averages!
The exact number will also vary depending on:
- the way your coffee was brewed
- your personal height and weight
Now, you may not be the cafe latte loving caffeine nut, but you LOVE your pourover coffees.
You will probably wonder if you can take 10 cups in a day too…
How many cups of drip coffee can you safely drink in a day?
You can take about 3 cups of drip coffee each day, safely.
Unfortunately, you cannot take as much drip coffee.
How much caffeine is there in drip coffee?
120mg in 5 oz (~147.8ml) [Source: Committee on Military Nutrition Research]
As above, we take 400mg as the safe daily dosage of caffeine. Which works out to about 3 servings of drip coffee.
Again, your favorite barista might brew their drip coffee using different ratios. And, your favorite cafe might serve their drip coffee in a bigger volume.
Since we are on the topic of coffee, there’s no way we can skip this question as well…
How many cups of kopi can I safely drink in a day?
Depending on the source, the amount of caffeine in robusta coffee (i.e. your kopi) is about 1.8 x to 2 x of that in arabica coffee (i.e. specialty coffee). See ref xxi., xxii (Chapter 1, Fig 1.4), xxvi.
You can probably drink about 5 cups of kopi everyday safely.
Although I get the buzz usually after my second cup…#weak
Can I die from drinking too much coffee?
probably not, unless you are downing a Adelaide Asskicker:
Kerrigan and Lindsey (2005) [ref ii] studied 2 cases of fatal caffeine overdose and concluded that ingesting more than 5g of caffeine would very likely lead to death. Other studies suggest that the fatal oral dose of caffeine is between 10g to 14g [ref iii].
The half-life of caffeine has also been reported to be about 5 hours [ref iii], i.e. it takes about 5 hours for your body to break down caffeine to half its amount.
Assuming 5g of caffeine will kill you, it will work out to about 125 cups of 8oz espresso-based coffees, or 41 cups of drip coffees…in less than 5 hours.
It’s highly unlikely that most of us would down that many cups…
The real danger comes with the overuse of energy drinks.
Can I measure the amount of caffeine there is in my coffee?
Coffee geeks, this is for you.
Refer to references vii and viii for experiments you can run to find out exactly.
Or use an approximation technique shared in coffee stack exchange [ref xxiii]:
For any amount of “good strength” coffee by any brew method, weigh the dry coffee in grams and multiply by 0.008, or 80mg of caffeine for each 10g of dry coffee.
We’ll explore the difference in caffeine content between dark vs light roast coffee, and between coffee brewing methods in Section II later.
Till then, let’s move on to…
Does espresso or drip coffee have more caffeine content?
*Hint*: This is a trick question.
If you have read the sections above on how many cups of coffee you can drink per day, safely…you would come to the conclusionthat drip coffee obviously has more caffeine 🙄
But yea, this is a trick question.
Be warned, all ye fellow baristas out there.
If you take a longer look at the table above, you’d notice that espresso has way more caffeine than drip coffee.
So…why can we consume less drip coffee in a day?
Well, because we usually don’t drink the espresso by itself.
Most espressos only come in a 1oz or 1.25oz doses. (even this is highly debatable, let’s not go down that rabbit hole today) The rest of your espresso-based coffee is made up in milk.
Now now, before you start feeling ‘cheated’…
Most people ain’t too excited about drinking espresso shots due to their intense and concentrated taste. Hence the espressos are usually served diluted, through various forms.
Back to the question, does espresso or drip coffee have more caffeine?
Here’s the quick answer in a glance:
If you are comparing an equal volume of espresso and drip coffee, espresso wins hands down.
If you are comparing an espresso-based drink (like that 8oz cafe latte you like to order from that handsome barista daily) and a regular serving of drip coffee (which is usually about 5-6oz, or 147 to 170ml), then the drip coffee has greater caffeine content.
How Caffeine Works
Here’s an in-depth and entertaining explanation of how caffeine works in your brain:
Does caffeine really help to keep me awake? How?
Caffeine has a similar chemical structure as Adenosine, a chemical that induces sleep.
Hence, it can occupy the adenosine receptors and prevent adenosine from doing its thing.
Why do I still feel sleepy after drinking coffee?
Your body gets used to your regular caffeine intake (aka tolerant) and become less sensitive to its effects.
Hence, you’ll realise that you might need to drink more coffee in order to stay awake.
Stop taking coffee for a few days. If the effects are very prominent, we suggest taking a break during the weekends…so that you don’t fall asleep at work :S
The Effects of Caffeine
Caffeine has been shown to:
- increase awakeness
- increase oxygen and nutrients going to brain, which helps alertness
- increases nutrients going to muscles, which helps boost athletic activity
- increases heart rate and concentration
In (unhealthy) high dosage, caffeine can lead to:
- nervousness, irritability
- uncontrolled bladder movements
- increased blood pressure
If you are in the mood to geek out, refer to ref vi, x in the references section below.
Is coffee addictive?
On top of inducing sleep, adenosine also blocks dopamine, the pleasure chemical ^^.
This means that caffeine indirectly induces pleasure. Not that kind of pleasure.😏
In a regular human, dopamine is required for regular survival behaviors like eating and having sex. Baby rats with the inability to produce dopamine stop eating and will starve, unless treated with dopamine-like drugs. [ref xi].
In short, dopamine helps us to look forward to activities that are crucial to our survival by rewarding us with ‘pleasure’ signals.
Many addictive drugs exploit this reward signal by boosting the dopamine levels, resulting in cravings.[ref xi]
Hence, you might find yourself getting addicted to coffee…only if you are highly dependent on it. If taken in a small amount- i.e. 1 cup a day, this effect is not as pronounced.
For perspective sake, an 8oz cup of espresso-based coffee only has about 0.27% caffeine content.
Here’s a quick video from National Geographic that explains how dopamine is linked to addiction:
[Interesting Fact!] There are studies being done on the effects of psychology in addiction. These researchers are finding that the chemical reactions mentioned above may be easily manipulated based on the user’s psychological condition. Hence, dopamine might not actually cause addiction. It’s a thought-provoking debate but I’ll try not to go off-topic here, so you can learn more if you are interested via references: xvi – xviii.
If you are curious about addiction, you can get an idea of the debate in this informative and intriguing (1 hour) lecture by Marc Lewis on The Neuroscience of Addiction @ The Royal Institute.
Are there long term (negative) effects?
Look out! Here’s another trick question…🤦
There are also debates surrounding the question of “will regular intake of coffee harm me over the long term?” or “Is coffee bad for you when taken over a long run?”.
Here’s the quick answer:
If you take less than 4 cups of espresso based coffee daily, you should be fine.
The occasional cafe hopping trips and coffee loaded days are fine too.
Daily consumption of a high level of caffeine can lead to negative consequences like: osteoporosis, high blood pressure, heartburn, anxiety, depression, infertility, etc [ref xx]
If you start experiencing tremors or increased heart rate, you should reduce your intake of coffee.
P.S. these effects are more likely to happen in you are an energy drink junkie. coffee junkies seldom hit crazily high caffeine levels, unless you are constantly drinking drip coffees, all day everyday.
Now, let’s see what we can find in the scientific research that have been published (and available to us).
Is it safe to drink coffee during pregnancy?
You might have read something somewhere that caffeine should be avoided during pregnancy.
But, what does research really tell us?
Nawrot et al (2003) concluded that most studies were not consistent. HOWEVER!
Many studies do support the believe that caffeine intake does affect pre- and post-natal development.
BUT! Only at a dose of more than 300mg per day.
So stay calm girls!
You can still drink your daily coffee, but try to watch your diet for other foods that may contain caffeine too.
And oh, if you smoke…you might want to give that up instead.
But of course, with so many inconsistent results. Just play safe lah, don’t drink or smoke when preggy ok? #bekiasu
Additional Reading: If you are a mother-to-be, or know someone who is expecting, you might be interested in the in-depth section on Caffeine and its effect on reproduction [page 12 of ref vi].
Is it safe to drink coffee while breastfeeding?
Well, the short answer is yes.
According to research, only 1% of caffeine from your bloodstream will be transferred to your baby via breastfeeding (ref. xxvii).
However, everybody reacts differently to caffeine and it is important for you to monitor your child’s response.
Section II: Caffeine and Coffee
We’ve answered all the FAQs on coffee and caffeine intake that we usually get from you.
Let us know in the comments below if you have a question that we didn’t answer!
Now, let us indulge in our favorite topic…
EDIT: This portion was placed at the top initially, but was moved down because it was deemed too ‘boring’ for the non-coffee geeks 🙁
Section II for the real coffee nuts like us…
Now, we’ll dive into the deeper relationship between coffee and caffeine.
- How much caffeine is there in a (raw) green coffee bean?
- Which has more caffeine – light roast coffee or dark roast coffee?
- Does the brewing method affect caffeine levels?
As per section I, you can click on the links above to skip to the question. AND and and, if you want to read more, refer to the juicy reference section below ^^.
How much caffeine is there in (raw) green coffee bean?
Coffee grows as a fruit.
Our favorite drink comes from extracting the ‘juice’ after roasting the beans within that fruit.
So, its only logical to wonder how much caffeine there is in a green coffee bean right?
As mentioned above, robusta coffee beans have about twice as much caffeine as compared to arabica coffee beans.
Coffee Chemistry indicates that robusta contains about 2.2 wt% caffeine while arabica contains about 1.1 wt%.
This simply means:
- Every 100 g of robusta beans contains about 2.2 g of caffeine
- Every 100g of arabica beans contains about 1.1 g of caffeine
Decaffeinated green coffee beans should have about 0.1% (w/w) caffeine.
Does roasting affect the caffeine level?
Roasting is known to create bitter tastes in coffee. However, according to Folmer et al [ref. xxii], “Although caffeine has as a strong bitter taste, it contributes only some 10% – 20% to the sensory perceived bitterness in coffee. It’s concentration does not change upon roasting.”
Instead the bitterness is due to the formation of other compounds like chlorogenic acid lactones and phenylindanes.
So, there goes the myth that “Starbucks coffee have more caffeine because their beans are
burnt roasted dark“. Myth Busted!
This also suggests that although the robusta used in our kopi is usually roasted dark, its caffeine level is higher than espresso-based coffee only because of the beans (see preceding section)
Does the brewing method affect the caffeine level?
In short, yes.
Caffeine is extracted during the brewing process. Hence, it is logical that the brew method will affect the amount in the final drink.
Caffeine is known to be highly soluble in water. And most of it is extracted within the initial phase of the brewing process.
Gloess et al (2013) suggest that an increase in extraction time did not lead to an increase level of caffeine. Instead, pressure seems to be a more significant contributor to the extraction of caffeine in coffee:
Ah..that’s all for now folks.
But, research about caffeine is an on-going process, and so it shall be the same with this piece.
Got something you don’t agree with? Say it in the comments below!
Section III: References
- i. [Video] The Science of Caffeine: The World’s Most Popular Drug
- ii. Fatal caffeine overdose (2005)
- iii. Caffeine for the Sustainment of Mental Task Performance (2001)
- iv. Beverage Intakes in the U.S. (2014)
- v. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children (2017)
- vi. Effects of Caffeine on Human Health (2010)
- vii. How to measure the amount of caffeine in my drink (Experiment Protocol)
- viii. Extraction of caffeine from tea leaves (Experiment Protocol)
- ix. [Video] How does caffeine keep us awake x. Caffeine and the central nervous system: Mechanisms of action, biochemical, metabolic and psychostimulant effects (1992)
- xi. Addiction, Dopamine, and the Molecular Mechanisms of Memory (2000)
- xii. Molecular Mechanisms of Drug Reinforcement and Addiction (1995)
- xiii. Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats (2010)
- xiv. [Video] The Science of Addiction: Here’s Your Brain on Drugs | National Geographic
- xv. The Safety of Ingested Caffeine: A Comprehensive Review (2017)
- xvi. [Video] Everything you think you know about addiction is wrong | Johann Hari (TED)
- xvii. No, dopamine is not addictive (Psychology Today)
- xviii. The Rat Park Experiment (results remain highly debatable)
- xix. Caffeine content in espresso vs drip coffee
- xx. Caffeine Drug Facts – Alcohol and Drug Facts (Australia)
- xxi. Coffee Chemistry – Difference between Arabica and Robusta Coffee
- xxii. The Craft and Science of Coffee
- xxiii. How can I figure how much caffeine in there in my cup?
- xxiv. Comparison of nine common coffee extraction methods:instrumental and sensory analysis (2013)
- xxv. Erowid Caffeine Vault: Content in beverages
- xxvi. Espresso Coffee: The Science of Quality
- xxvii. Breastfeeding and Caffeine. La Leche League Canada. (2014)
Other intriguing studies on Caffeine: