You order decaf because you don't want to lie awake at night, you're expecting, or you're simply trying to drink less caffeine. But are you really getting a drink with no caffeine?
In short. Not quite. "Decaf" means most of the caffeine has been removed, not all of it. In one US study, decaf coffee bought from coffee shops contained between 0 and 13.9 mg of caffeine in a 473 ml (16 oz) serving. For comparison, the same volume of regular filter coffee has roughly 160–214 mg (80–107 mg in a 237 ml cup).
What the researchers found
In 2006, scientists measured the caffeine in 22 decaf coffee samples. Ten were bought from different coffee shops and contained between 0 and 13.9 mg per 16 oz (about 473 ml) serving. Another twelve came from one well-known coffee chain: brewed decaf had 12.0–13.4 mg per 473 ml serving, and a shot of espresso had 3.0–15.8 mg.
That's not much, but it isn't zero. Two such 473 ml servings a day would mean roughly 24–27 mg of caffeine, about a quarter of what one 237 ml cup of regular filter coffee contains.
Keep in mind that this was a small study, and the amount of caffeine left depends on the coffee, the producer and how it's prepared.
What "decaffeinated" means under the rules
In the European Union, soluble (instant) coffee extract can be labelled "decaffeinated" if it contains no more than 0.3% caffeine of the coffee dry matter. That isn't "0 mg": it's the limit up to which caffeine may be left in.
Who it matters for
- During pregnancy. The recommended limit is 200 mg of caffeine a day, so a few cups of decaf are unlikely to change much, but it's still worth counting (see our article on tea during pregnancy).
- If you're sensitive to caffeine or have a medical condition. The study's authors point out that people whose doctors have told them to restrict caffeine (for example, some people taking anti-anxiety medication) should be told that decaf contains traces. Even a small amount may matter for them; it's best to ask your doctor.
- When quitting coffee. Decaf helps you keep the ritual but doesn't remove caffeine completely. For withdrawal symptoms see caffeine withdrawal, and for cutting back gradually see how to quit coffee.
- Before bed. A small amount usually doesn't interfere, but if caffeine affects you strongly, it's safer in the evening to choose naturally caffeine-free drinks such as rooibos or other herbal teas.
How to find out how much caffeine you've had
The amount depends on the coffee, the producer and how it's prepared. You can add it up with our caffeine calculator or compare drinks in the converter.
General information, not medical advice.