Why caffeine guidelines differ between countries

On the headline number, everyone says the same thing: about 400 mg a day for a healthy adult. That holds in Europe, in the US and in Canada.

The real divergences are elsewhere, and the one with the biggest practical consequences isn’t a scientific disagreement at all: it’s a unit of measurement. US guidance counts 355 ml cups. A reader picturing espressos while reading “2 to 3 cups” is out by a factor of five.

	Adult	Single dose	Pregnancy	Children and teens
EFSA (Europe)	400 mg	200 mg	200 mg	3 mg/kg
FDA (US)	400 mg	—	—	—
Health Canada	400 mg	—	300 mg	2.5 mg/kg
ANSES (France)	No figure of its own

The cup trap

This is the commonest source of error when reading guidance across borders, and it’s purely practical.

The FDA phrases its reference as 400 mg, “about two to three 12-fluid-ounce cups of coffee”. Twelve fluid ounces is 355 ml — a large cup of filter coffee. It separately notes that an 8-ounce cup (240 ml) holds 80 to 100 mg.

Against real-world containers, that gives:

“A cup” according to whom	Volume	Caffeine
A café espresso	25–30 ml	60–80 mg
A small cup of filter	125 ml	50–65 mg
A mug of filter	240 ml	80–120 mg
An FDA “cup”	355 ml	~150 mg

A US cup is therefore roughly twice a European mug and five times an espresso. “Three cups a day” means 450 mg on one side of the Atlantic and 210 mg at a European counter — two entirely different days.

It’s also why US reference tables always look high to a European reader: they describe containers nobody drinks here. The real everyday volumes are in caffeine content by drink.

Where the agencies genuinely differ

Two gaps exist, and they concern sub-populations rather than the average adult.

Pregnancy. EFSA sets 200 mg a day, Health Canada 300 mg. That isn’t a scientific contradiction but a difference of method and precautionary margin: both agencies assess the same literature and don’t place the line in the same spot. It’s a subject where the only good answer comes from a health professional who knows the situation, not from a table.

Children and adolescents. EFSA cites 3 mg per kilo per day, Health Canada 2.5 mg per kilo. The gap is modest, but it illustrates the same phenomenon: where data are thinner, agencies diverge more. Reference points for teenagers are covered in caffeine and teens.

And France?

France has no figure of its own. ANSES publishes no daily limit for the general population: it works from internationally established thresholds and speaks instead to specific situations — pairings to avoid, groups to watch, energy drinks.

So the “400 mg” quoted everywhere in French is a European figure, not a French one. What the French agency contributes in its own right — notably measuring what people actually consume — is covered in what ANSES says about caffeine.

Why these differences exist

Three reasons, none of which requires any agency to be wrong:

• Mandates differ. EFSA issues scientific opinions at the European Commission’s request. The FDA is a regulator that also speaks to the public directly. Health Canada does both. The shape of the recommendation follows the mandate.
• Dates differ. EFSA’s reference opinion is from 2015; Health Canada’s guidance is older. Recommendations are never revised everywhere at once.
• Precautionary margins differ. From identical literature, two agencies can choose different safety factors, especially where data on a population are limited.

What to do with it

The practical conclusion is simple, and it holds whatever the country: count in milligrams, not in cups.

The 400 mg figure is robust and shared. What isn’t is its translation into containers — because a container isn’t the same size depending on where you are, or what the drink is. A US article saying “four cups” and a European one saying “five espressos” both describe 400 mg; they don’t describe the same day.

The reference point itself, and why your own limit may sit elsewhere, is covered in how much caffeine per day.

What to take away

The authorities agree on the essentials: 400 mg a day for a healthy adult, and 200 mg in a single sitting on the European side. That consensus is firmer than the contradictory articles in circulation suggest.

The real divergences concern pregnancy and children, where agencies set the line differently — and on those subjects a health professional comes before any general reference.

The rest of the apparent contradictions come down to one unit: the cup, which doesn’t hold the same thing on both sides of the Atlantic.

CaffIQ counts in milligrams for exactly that reason — it’s the only unit that doesn’t change meaning when it crosses a border.

CaffIQ provides general estimates, not medical advice. For any health question, talk to a qualified professional.