Tea caffeine estimator
Build a rough estimate from FDA reference values for 12-fluid-ounce servings of green and black tea. Your actual drink may contain more or less.
Tell us about your cup.
These FDA figures are category reference amounts, not measurements of individual tea products. More accurate numbers may be available on your product label.
Green tea × 2 (12-fl-oz servings).
Shown relative to the FDA's 400 mg/day reference for most adults. This is NOT an individualized safety limit or intake recommendation.
Where these numbers come from
The U.S. Food and Drug Administration provides examples of 37 mg of caffeine in 12 fluid ounces of green tea and 71 mg in the same amount of black tea. Individual beverages differ by tea variety, amount of leaf, brewing method and serving size. Multiplying those examples by cups only gives a general comparison.
What if I drink both kinds?
This first version estimates one type at a time. You can calculate each type separately and add the results. If a product label lists the amount of caffeine, prioritize that measured value over this generic estimator.
What about the 400 mg marker?
For most adults, 400 mg of caffeine per day is an amount the FDA says is not generally associated with negative effects. It is not a goal, a guarantee of safety or the right number for everyone. Pregnancy, medications, health conditions and individual sensitivity may require different limits. Ask your healthcare professional if you need personal advice.
Continue learning
Read our caffeine-in-tea guide or compare black tea and green tea to understand why numbers vary.