How much caffeine is in filter coffee?

I’m not sure if you’ve ever had this before, but today I drank a little bit more coffee than usual and it triggered a bit of a buzz for the first time in a while! 

It’s pretty unusual for me to get a head rush from caffeine as I usually drink a cup (or two) most days, so it made me curious to investigate what impact coffee is having on my body and better understand sensible limits for consumption!

How much caffeine is in ground coffee?

At a glance…

  • There is 7.2g of caffeine in my morning coffee (500ml)
  • There is around 40mg of caffeine in 100g of ground coffee
  • Caffeine is a naturally occurring drug
  • It is not addictive, but confusingly can trigger withdrawal symptoms for some
  • It is lethal in large doses
  • My lethal dose is around 1,429 coffees (714 litres!)

What is caffeine?

Caffeine is an unregulated psychoactive drug which prevents onset of drowsiness as it temporarily blocks the impact of adenosine (one of four components of ribonuclease acid, or “RNA” that are vital for life) in the brain as well as directly stimulating the nervous system.

While you and I most likely consider caffeine as synonymous with coffee and tea it is also found in various other plants which offers them some defensive properties (keeps predators away!)

Interestingly caffeine is NOT considered addictive as it doesn’t trigger the same behavioural shift as other recreational drugs – coffee users wouldn’t do crazy things to get their next ‘fix’.

Despite this, it CAN trigger withdrawal symptoms in some people if they stop consuming.

So what does this mean for us?

Well a cup of Joe keeps us sharp, it keeps us awake and it keeps us in a good mood (if we are used to consuming it regularly!)

Is it dangerous to consume a lot caffeine every day?

In normal quantities the answer is generally no.

It can be lethal in huge doses though, and the dose which would kill us is different for everyone.

The amount of caffeine which would be required to kill around half of a test group (known as an “LD50”, where LD stands for lethal dose) is around 150-200mg/kg.

So for me (at around 70kg) that puts my threshold around 10 – 11 grams.

Yikes – that doesn’t seem like a massive amount…!

So… How much caffeine in filter coffee?

Of course this wouldn’t be a blog post without an ambiguous answer – so here it is:

It depends.

It depends on how strong a coffee you like, how big your cup is, the source of the beans, etc.

BUT as we kicked all this off with my coffee buzz we can work out how much caffeine is in my cup of java at least!

My preferred way to make a filter coffee is with a drip machine (my trusty Technivorm Moccamaster) using around 18 grams of ground beans to make 500ml of coffee. The other key fact we need to know is how much caffeine is in ground coffee: there is around 40mg of caffeine per 100 grams of ground coffee beans.

So for my morning coffee I am consuming around:

40mg x 0.18 = 7.2g of caffeine per 500ml servicing

Interestingly the lethal dose (LD50) for me is equivalent to 1,429 morning coffees, all consumed at once! That’s a whopping 714 litres of coffee.

I think I’m safe with my one-a-day habit.

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