At 58.5 mg per fl. oz., Black Insomnia is more than twice as strong as Starbucks' dark roast, at around 21.25 mg per fl. oz. This all depends on how you brew the coffee, of course. Kristafor said this level is well within limits for a shot, but one cup (12 oz.) could add up to 702 mg of caffeine. The FDA and the International Food Information Council recommend 400 mg of caffeine for daily consumption.