A typical cup of tea contains about 15 to 70 milligrams of caffeine, with the exact amount depending on the type of tea and how it's brewed. Here’s a quick breakdown to guide you:

• Black tea: roughly 40–70 mg per 8 oz cup.
• Green tea: roughly 20–45 mg per 8 oz cup.
• White tea: roughly 15–30 mg per 8 oz cup.
• Oolong tea: roughly 30–50 mg per 8 oz cup.
• Herbal teas: typically caffeine-free, unless blended with caffeinated tea leaves.

Factors that influence caffeine in tea:

• Tea type: less-processed teas (like white) generally have less caffeine than black, but variability exists.
• Brewing time: longer steeping increases caffeine extraction.
• Water temperature: hotter water can extract more caffeine; boiling water may raise extraction compared to water just below boiling.
• Tea leaf quality and processing: older or lower-grade leaves may yield different caffeine levels.

If you’re monitoring caffeine intake, use these ranges as a general guide and consider brewing shorter (1–3 minutes) with cooler water if you want a lighter caffeine boost. If you’d like, specify the tea type you drink and your typical cup size, and I can give a more precise estimate.