The lightest common chocolate for caffeine
USDA measures milk chocolate at 20 mg of caffeine per 100 g, which works out to about 6 mg in a 1 oz piece and 9 mg in a standard 1.55 oz bar. That is a small fraction of an 8 oz cup of drip coffee at USDA’s reference strength (95 mg): a full bar carries less caffeine than a tenth of a cup.
Milk chocolate’s caffeine comes from the same source as any chocolate, the cocoa solids, but it has much less cocoa per gram than dark chocolate. USDA’s figure for dark chocolate at 70 to 85% cacao is 80 mg per 100 g, four times milk chocolate’s 20 mg, and the pattern holds generally: more cocoa solids and less milk and sugar means more caffeine, ounce for ounce.
Against hot chocolate and coffee beans
An ounce of milk chocolate (6 mg) carries less caffeine than an 8 oz cup of hot chocolate made with milk (about 7 mg), even though the candy bar has far more concentrated cocoa than a mug diluted with milk and water. That’s a reminder that finished-drink figures and candy figures aren’t directly comparable serving for serving.
The other end of the chocolate scale is dramatic: dark chocolate-covered coffee beans carry actual coffee inside the chocolate shell, and USDA measures them at 839 mg per 100 g, more than 40 times milk chocolate’s density.
Where it adds up
For most adults, milk chocolate is negligible next to the 400 mg daily figure the FDA cites for healthy adults; a whole bag of fun-size bars would be needed to approach it. It matters more for children, whose smaller daily allowances make even a low-caffeine snack a real share of the total, and worth remembering that the FDA notes caffeine in a food like chocolate does not have to appear on the ingredient list, since it occurs there naturally rather than being added.