About 160 mg per 16 oz can
A standard 16 oz can of Monster Energy contains roughly 160 mg of caffeine — about the same as 1½ cups of coffee, or 40% of an adult's 400 mg daily ceiling. The bigger 24 oz "Mega" cans push that toward ~240 mg. See it ranked against everything else on the caffeine chart. (Per the standard original can; Monster's many varieties differ — check the label.)
What that means for your day
- One can is fine for most adults — but it's your big caffeine hit, so go easy on coffee around it.
- Two cans (~320 mg) leaves little room before the 400 mg limit.
- The sugar in regular Monster (~54 g) is the bigger everyday health issue — the zero-sugar versions keep the caffeine, drop the sugar.
Work out exactly how a Monster fits your body with the intake calculator.
Monster and your sleep
160 mg is a real dose, and energy-drink caffeine tends to be drunk fast and late. A Monster in the afternoon can still have a good chunk of caffeine in your system at bedtime, quietly cutting your deep sleep. If you have one after midday, check what's left at bed with the half-life calculator. For the full picture, see are energy drinks bad for you.
Put it into practice: add a Monster to your day and see if you're still under the limit with the intake calculator.