Caffeine calculator

How much caffeine is too much?

For healthy adults, the European Food Safety Authority (EFSA) found that up to 400 mg a day, spread through the day, raises no safety concerns. It gave a separate figure for one sitting: single doses up to 200 mg, about 3 mg per kg of body weight. EFSA also noted that 100 mg can affect sleep in some adults, particularly close to bedtime.

Lower limits apply to some people:

• Pregnant: no more than 200 mg a day, the NHS says, because too much caffeine has been linked to a higher chance of miscarriage and stillbirth.
• Breastfeeding: no more than 200 mg a day. Caffeine reaches your baby through breast milk, and the NHS says a lot of it may make them restless and keep them awake.
• Children and teenagers: EFSA proposed 3 mg per kg of body weight a day, so about 150 mg for someone who weighs 50 kg. Pick "Under 18" in the calculator and add their weight to see it.

How much caffeine is in coffee?

It depends far more on where the coffee comes from than on what it's called. The NHS uses 100 mg for a cup of instant coffee. Coffee-shop drinks are often much stronger, because a medium cup can hold two or three espresso shots. Costa's own figures, for example, put a medium latte at 200 mg and a medium cappuccino or americano at 325 mg, more than EFSA's single-dose figure for adults in one cup.

Espresso itself varies a lot. When researchers at the University of Glasgow bought 20 espressos from Glasgow coffee shops in 2012, the caffeine in a single shot ranged from 51 mg to 322 mg. The calculator uses the middle value of 140 mg for a generic shop espresso, and each chain's own figure where it publishes one.

Decaf isn't completely caffeine free, but it's close: Nescafé gives 2 to 5 mg for a mug of its decaf instant, and Costa 2 mg for a decaf double espresso.

How much caffeine is in a cup of tea?

The NHS uses 75 mg for a cup of tea in its pregnancy advice and 55 mg for a mug of tea in its breastfeeding advice. Brewing time matters: Yorkshire Tea gives 48 mg for a 200 ml mug brewed for five minutes. Green tea is usually lower, at 38 mg a mug in the NHS breastfeeding figures.

How much caffeine is in energy drinks?

A 250 ml can of energy drink has about 80 mg, the same as a mug of instant coffee. Bigger cans add up fast. Red Bull gives 114 mg for its 355 ml can and 151 mg for 473 ml, and a 500 ml can of Monster has 160 mg. Two large cans in a day takes an adult most of the way to 400 mg before any tea or coffee.

In the UK, any drink except tea and coffee with more than 150 mg of caffeine per litre must carry the words "High caffeine content. Not recommended for children or pregnant or breast-feeding women" on the label.

How the calculator works

Tap + for each drink or bar you have in a normal day, pick who it's for, and it adds up the caffeine and compares the total with the matching limit. If one serving you've picked has more than 200 mg, it says so, because that is over EFSA's single-dose figure for adults. Where the NHS or EFSA gives a rough figure ("less than 25 mg" for a bar of dark chocolate), the calculator uses the upper figure.

Labels and recipes change, and coffee-shop drinks vary from cup to cup, so treat the total as a good estimate rather than a measurement. Caffeine also turns up in some cold and flu remedies and painkillers; check the packet if you take them.