How much caffeine did you drink today? This is a question that we coffee lovers may not always think about whilst enjoying our favorite brew. Well, our quick caffeine calculator can help you answer that question
If you want to learn more then please read on…
First, let us take a quick look at caffeine. What is it and why should we take notice of how much we drink?
What is caffeine?
Caffeine is an organic molecule which means that it is present in living things and has a structure comprised of carbon atoms. Other atoms such as oxygen, hydrogen, nitrogen, and phosphate can also be ‘attached’ to the carbon to give many organic molecules.
However, not all molecules made from carbon are organic. For example, diamonds and graphite are made of carbon but are not considered organic.
Caffeine is a natural molecule in that it occurs naturally in living things and has the following molecular structure.
By-the-way, don’t confuse organic molecules with organic produce. For example, the name ‘organic’ in growing vegetables usually means that no synthesized fertilizer has been used during farming (it may still use ‘natural fertilizer’ such as coffee grounds).
You may not know it but a lot of chemistry happens with coffee at all steps from farming to your final brew.
Chemistry happens during the growth of the coffee cherry, during processing, during roasting, and finally when you make your favorite brew.
In particular, when we make our coffee we are performing the chemical procedure of solvent extraction.
That is, we take the organic material (roasted coffee bean), grind it (to increase the surface area), add solvent (water) and wait (with a little mixing if we use a manual brew method).
We then filter the insoluble coffee grinds leaving us with our lovely cup of brewed, solvent extracted, coffee.
For greater detail on the effects of caffeine we recommend Examine.com. They scrutinize current scientific research and provide independent reports on caffeine and many other supplements. Examine.com is one of our go-to places for trusted and reliable information.
Why Should We Take Notice Of How Much Caffeine We Drink?
There are pros and cons of drinking coffee and some people are rightly concerned about side effects or addiction to caffeine in the coffee.
Each of us reacts to caffeine (or any other drug) in a different way and some of us are sensitive to coffee and some of us aren’t.
Actually, caffeine is relatively safe, not considered addictive, and a lethal dose is just way too high for most people to achieve with normal drinking (but beware of caffeine tablets and powders).
Coffee, and caffeine in coffee, can have many health benefits and can be good for you. However, it is a good idea to monitor coffee, and caffeine, consumption especially for people who may be at risk by ingesting caffeine.
People that are most at risk for the effects of coffee are pregnant women, children, and those with a sensitivity to coffee. Scientific studies (Li&2015) seem to indicate that coffee may induce pregnancy loss. Other studies (Wierzejska&2019) indicate that there is no effect on the growth characteristics of newborn babies whose mothers ingest caffeine by drinking either coffee or tea.
New scientific studies will, no doubt, reveal other pros or cons of caffeine. In any case, it would seem wise for pregnant women, children (i.e. the parents of children), and people sensitive to caffeine to exercise caution and monitor their caffeine intake.
What is a lethal dose of caffeine in humans?
A lethal dose of caffeine in humans hasn’t been determined (mainly because no one wants to be the subject of an experiment that may lead to their death!) and estimates of a lethal dose for humans is usually based on animal (mainly rat) studies.
A common measure of acute toxicity is the LD50. The LD50 is the single dose (remember this for later) of a chemical that kills 50 percent of the experimental animals within 14 days of administration. The LD50 of a chemical is expressed in milligrams of chemical per kilogram of body weight (mg/kg).
The table below shows the LD50 for some common chemicals, but adjusted to a human equivalent dose (HED). That is, we used a conversion factor from the scientific literature (Nair&2016) to convert rat LD50 into an estimate of human LD50.
Table of Human Equivalent of LD50 & Lethal Dose for Dome Common Chemicals
We used the World Health Organization classification of toxicity in the table (as stated in Wikipedia which classifies toxicity as follows:
- Extremely toxic <5 mg/kg
- Highly toxic 5 to 50 mg/kg
- Moderately toxic 50 to to 2000 mg/kg
- Slightly toxic more than 2000 mg/kg
A chemical with a small LD50 (e.g. 1 mg/kg) is considered extremely toxic. A chemical with a large LD50 (e.g. 2,000 mg/kg or above) is considered slightly toxic. The value of the LD50 also depends upon how the chemical is administered (e.g. orally or by injection).
The LD50 isn’t the complete story because it doesn’t tell us the rate at which the chemical becomes toxic as the dose increases.
However, for our purposes we will use it as a guide. As you can see from the table any chemical, even water, can be toxic if the dose and the exposure to the chemical is high enough.
We calculate that the LD50 for humans should be about 56.43 mg/kg. This calculation gives a value greater than that shown in the table (32 mg/kg). We used recent scientific data from rats and the same conversion factor we used for the table values.
In contrast, caffeine informer estimate the LD50 to be about 150 mg/kg. This just shows that these estimates can be a bit ‘rubbery’ (imprecise) when inferred from animal studies and often depend on the assumptions made in the calculations.
What does this LD50 mean when drinking coffee?
Well, if you weigh 70 kg then your potential lethal dose of caffeine would be about 3950 mg or about 4 g (0.14 oz) of caffeine (56.43 mg/kg x 70 kg = 3950 mg).
That is, you would need to ingest about 4 g of caffeine in one dose at the same time to have potentially lethal effects. How many cups of coffee would you need to drink at one time to ingest 4g?
Let us assume that a 30ml single shot Espresso coffee has about 3.11 mg/ml of caffeine (we use mg, ml, kg for our calculations because most scientific studies use the metric system). This gives a total of 93.3 mg caffeine in one 30 ml shot. The quantity of 3.11 mg/ml is taken from a scientific article by Poole&2019 and we refer to this article in the calculations below.
In this case, you would need to drink about 43 shots, or 1290 ml (44 fl.oz) of Espresso all in one go! Is this possible? Maybe, but why the heck would you?
What is a Cup of Coffee?
Seems like a silly question doesn’t it?
Often we may think of having a ‘cup of coffee’, but we are not immediately aware of the volume of that ‘cup’. In fact, the volume of a ‘cup’ can vary considerably. There is a standard called a US legal cup (about 240ml or 8 fl.oz) and this seems to be used in a cafe to serve long black, Americano, latte, cappuccino, mocha, or flat white.
However, if you use a pour over coffee maker such as the Kitchen Aid KCM1208DG shown below and you use the cup guide shown on the side of the carafe then you would pour yourself about 147 ml (5 fl.oz) for a ‘cup’ of coffee.
- Short: 8 fl. oz. or 237 ml (usually one 30ml shot espresso + 207 ml milk/water)
- Tall: 12 fl. oz. or 355 ml
- Grande: 16 fl. oz. or 473 ml (usually two shots of espresso)
- Venti® Hot: 20 fl. oz. or 592 ml (usually two shots of espresso with more milk)
- Venti® Cold: 24 fl. oz. or 710 ml
- Trenta® Cold: 31 fl. oz. or 917 ml
What is a Coffee Unit?
The varying sizes of a ‘cup of coffee’ can cause problems especially when trying to compare caffeine content and human consumption in scientific studies.
If you don’t have a ‘standard’ in a scientific study then it is difficult to make comparisons between scientific data, results in many different values, and potential misclassifications of coffee (and caffeine) consumption.
Consequently, a study by Poole&2019 set out to develop a ‘coffee unit’ that not only accounted for cup size but also for the preparation method (e.g. instant, espresso, French Press, and filter). They created this coffee unit by measuring both caffeine and chlorogenic acid concentrations in coffee prepared by various methods and standardizing to a cup of 237 ml (8 fl.oz). They used data already reported in the scientific literature as well as their own measurements.
A ‘coffee unit’ is useful because it may avoid misclassification of coffee consumption. That is, a coffee drinker may think that he/she drank ‘3’ cups of coffee in a day, but the coffee unit may indicate that he/she actually drunk ‘4’ cups of coffee. Thus, the coffee drinker underestimated their coffee (and caffeine) intake for the day.
However, the scientists also recognized the limitations of their ‘coffee unit’. In particular, the caffeine content of any coffee drink will vary depending upon the growth and origin of the coffee bean, the type of coffee bean (e.g. Robusta or Arabica), the roasting method, the brewing method, and a host of other conditions. Nevertheless, the concept of a ‘coffee unit’ is useful and we use this coffee unit in the Caffeine Calculator
We used scientific data to build this calculator but you should recognise that many assumptions are made even when scientific data is used.
Furthermore, whilst we make every effort to ensure the accuracy of the results they should NOT be taken as a recommendation, they should not be used for any technical purpose, and they should NOT be construed as medical advice or used for any medical purpose. Please refer to our disclaimer policy.
The Caffeine Calculator
The Caffeine Calculator allows you to find out how much caffeine you ingested today from drinking coffee.
We currently only look at drinking coffee and do not include coffee supplements (tablets or powders) as yet.
How to use the Caffeine Calculator
- Type a number for each type of drink. For example, if you had 2 espresso drinks just type the number 2. Do not type any units.
- Select the unit of measurement. For example, if you had 2 cups of pour over coffee (148ml or 5 fl.oz) then select cup.
- The volume of a ‘cup’ can vary but you can select small, medium, large, or Extra Large to match what you usually drink.
- If you know the volume of your drink (or it doesn’t match the preselected volumes), then select either milliliters (ml) or fluid ounces (fl.oz)
- If you know the weight of your drink then select either gram (g ) or ounces (oz).
- Select single, double, or triple shots if you just had an espresso
Want to know more about caffeine?
Interested in learning organic chemistry? Then try a great course at masterorganicchemistry.
Adamson, R. H. (2016). The acute lethal dose 50 (LD50) of caffeine in albino rats. Regulatory Toxicology and Pharmacology, 80, 274-276.
Farah, A., & dePaula Lima, J. (2019). Consumption of chlorogenic acids through coffee and health implications. Beverages, 5(1), 11.
Nair, A. B., & Jacob, S. (2016). A simple practice guide for dose conversion between animals and human. Journal of basic and clinical pharmacy, 7(2), 27.
Poole, R., Ewings, S., Parkes, J., Fallowfield, J. A., & Roderick, P. (2019). Misclassification of coffee consumption data and the development of a standardised coffee unit measure. BMJ Nutrition, Prevention & Health, bmjnph-2018.
Rahal, A., Kumar, A., Singh, V., Yadav, B., Tiwari, R., Chakraborty, S., & Dhama, K. (2014). Oxidative stress, prooxidants, and antioxidants: the interplay. BioMed research international, 2014.
Satel, S. (2006). Is caffeine addictive?—A review of the literature. The American journal of drug and alcohol abuse, 32(4), 493-502.
Lethal Dose table from Cornell University