The strongest of USDA’s dark chocolate bands, per gram
USDA measures chocolate in the 60 to 69% cacao range at 86 mg of caffeine per 100 g, which comes to about 24 mg in a 1 oz piece and 96 mg in a full 112 g bar. That is slightly higher per gram than USDA’s figure for 70 to 85% dark chocolate, 80 mg per 100 g, even though the 60-69% band has a lower cacao percentage on the label.
Percentage isn’t a reliable predictor
This is the clearest example on the menu of why a higher percentage on the wrapper doesn’t guarantee more caffeine: USDA’s own figures put this 60-69% chocolate slightly ahead of the 70-85% band. Both, unsurprisingly, carry much more than 45 to 59% dark chocolate (43 mg per 100 g) or milk chocolate (20 mg per 100 g).
Because USDA groups chocolate by cacao percentage band rather than testing every individual bar, a specific product within the 60-69% range could measure a little above or below 86 mg per 100 g; the wrapper’s percentage is a reasonable guide, but not a precise one, for caffeine specifically.
Where it fits in a day
An ounce, 24 mg, is a tiny fraction of the 400 mg daily figure the FDA cites for healthy adults; a full bar, 96 mg, is still under a quarter of it. It matters more late at night, since caffeine’s mean half-life of about five hours (NCBI) means an evening square adds a little to whatever’s already circulating, and more for children, whose smaller daily allowances make a few squares a bigger share of the day.