Caffeine content of tea and coffee will vary widely. For coffee, smaller grind size, brewing method, the bean type (there are low/decaf cultivars,) roasting me

Caffeine content of tea and coffee will vary widely. For coffee, smaller grind size, brewing method, the bean type (there are low/decaf cultivars,) roasting method, and water temperature (to name a few) will affect how much caffeine ends up in your cup. Expecting Starbucks to give you a consistent dose cup after cup, month after month is probably a bit optimistic.