Some surprises about coffee strength.
"Caffeine extraction is linked to contact time"
— James Hoffmann
I'd wanted to have some of this in my piece the myth of "strong coffee", but in trying to find sources beyond a james Hoffmann video, ran out of patience, so now I feel it's time to add some numbers, albeit belatedly. in brief, espresso is not the strongest caffeine content.
Because there's not an easy and cheap way of measuring caffeine content, there aren't many hard numbers available, and those I did find vary wildly. I've settled on Hoffmann's numbers in his video here. With the help of AI, I did get some other sources, which I will link to, and enable you to compare numbers. Many health sources advise drinking no more than 300mg/day. So know you know roughly how many cups you could drink. I imagine that my 3-cup moka express has about 150mg for the full three cups of coffee, so I'm already on thin ice, hence shifting to decaf before midday.
That's caffeine! Bear in mind that robusta coffees in many chaper commercial coffees, is higher in caffeine than an eqivalent amoutn of arabica. For "strength," Hoffman talks about total dissolved solids, using a refractometer to measure. He aims for a 21% TDS in his finished cup, out of 18 grams of ground coffee for each brew method, but I can't find equivalent figures for other methods.
It also has to be said that there are not many ways to cheaply and accurately measure caffeine content, which (as mentioned) depends on many factors, from bean origin, roasting style and precise brew method. Two adjacent cafes' espressos may vary wildy in their caffeine levels, so this table should be taken as a rough guide only.