How Much Caffeine is in Your Tea?-USDA Data & Brewing Guide

How Much Caffeine in A Tea Bag?

According to the latest data from the U.S. Department of Agriculture (2025), the caffeine content per standard cup (230ml) of common tea varieties falls within the following ranges: black tea contains 40–70 mg (averaging 47 mg), green tea 20–45 mg (averaging 29 mg), oolong tea 30–50 mg, and white tea 15–30 mg, while pure herbal teas are virtually caffeine-free. These differences primarily stem from tea varieties (e.g., Assam varieties contain higher levels than small-leaf varieties), harvesting practices (young buds have significantly higher content than mature leaves), and processing methods.

The actual release of caffeine is also heavily influenced by brewing methods. Studies show that using boiling water (≥95°C) to steep tea for five minutes can increase caffeine extraction by 50%–70% compared to steeping at 80°C for two minutes. Additionally, tea bags made from broken leaves typically release caffeine faster and may yield higher total amounts compared to whole-leaf tea bags.