Filter coffee: 72mg per brewed 150ml serving
As expected, coffee gives a serious caffeine hit, comparable to that delivered by energy drinks. Strength of brew will change this averaged value significantly.
Espresso coffee: 58-185mg per double shot
Espresso strengths vary wildly – even among branches of the same coffee chain. A single espresso in one café could contain more caffeine than a double shot in another.
Tea: 36mg per brewed 150ml serving
Significantly weaker in principle – but if tea is brewed strongly that value rockets to make it comparable with coffee.
Diet Coke: 47mg per 330ml can
Higher than regular Coke (35mg), the world’s favourite cola drink contains a comparatively modest caffeine hit.
Red Bull: 80mg per 250ml (small) can
Surprisingly in view of its marketing, Red Bull delivers a boost no greater than that delivered by coffee.
Monster energy drink: 160mg per 500ml can
The same concentration of caffeine as Red Bull, but a bigger size as standard. Because of their lower cost, drinks such as Monster and Relentless are popular with young people.
Daily allowance based on 400mg per day for moderate consumption, when no other caffeine is consumed.
Sources: Caffeinated by Murray Carpenter, The Guardian, Wired magazine.