Slightly less than a plain latte
USDA’s survey figure for café mocha is 33 mg of caffeine per 100 g, just under the 36 mg per 100 g it gives a latte or cappuccino. That comes to 82 mg in an 8 fl oz cup, 123 mg in a 12 fl oz Small, 164 mg in a 16 fl oz Medium and 205 mg in a 20 fl oz Large. The gap is mostly volume, not chocolate: chocolate syrup and cocoa add weight and sweetness to the cup, which slightly dilutes the caffeine per 100 g compared with a mocha’s plain-latte cousins, even with the same shots underneath.
Chocolate itself contributes very little here. USDA measures unsweetened cocoa powder at far higher caffeine density than a finished mocha, but a mocha uses only a spoonful of syrup or powder per cup, so almost all of the drink’s caffeine still comes from its espresso, not its chocolate.
Against a Starbucks-style mocha
Coffee chains build a mocha the same way they build a latte, from a fixed shot count rather than a scaling ratio. A Grande Starbucks Caffè Mocha carries 175 mg by Starbucks’ own published nutrition data, more than the 16 oz USDA figure for a home or diner mocha (164 mg), since Starbucks’ espresso runs stronger per shot than the survey average and its mocha sauce adds a little caffeine of its own.
Where it sits against your daily total
A Small mocha at 123 mg is well under a third of the 400 mg daily figure the FDA cites for healthy adults. The Large, 205 mg, is the size that edges past the 200 mg EFSA assessed as a safe single dose for healthy adults, by just 5 mg, so it sits right at that line rather than clearly over it.
Pair it with food that also carries caffeine and the total moves fast: a Medium mocha (164 mg) and an ounce of dark chocolate (23 mg) come to 187 mg, still under the EFSA single-dose figure but worth noting if anything else caffeinated is still to come that day.