Coffee and tea both contain caffeine, and comparing them requires a defined serving. FDA reference figures for 12-fluid-ounce drinks list about 37 milligrams for green tea, 71 for black tea and a broad 113–247 milligram range for regular brewed non-specialty coffee. These are examples, not an exact conversion for every cup or café.
The dry ingredients and the finished beverage are different comparisons. Dose, water, steeping and the product itself affect how much caffeine reaches the drink. Milk and extra water can change perceived strength without removing caffeine already present. Decaffeinated versions also retain some caffeine.
Tea contains compounds such as theanine, but that does not guarantee a calm response or cancel caffeine's effects. Individual sensitivity, medicines and health circumstances matter. Use product information and actual portion sizes when tracking intake, including other foods and drinks. For a personal restriction, ask a healthcare professional rather than choosing solely through the words coffee or tea.
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