Brewed black tea has 47mg of caffeine per 8 oz cup and decaf tea has 4mg per 8 oz cup, so the gap is about 12x. You would need roughly 12 servings of decaf tea to match one 8 oz cup of brewed black tea.
Decaf tea vs brewed black tea: the numbers
| Decaf tea | Brewed black tea | |
|---|---|---|
| Caffeine per serving | 4mg per 8 oz cup | 47mg per 8 oz cup |
| Caffeine per fl oz | 0.5mg | 5.9mg |
| Servings to reach 400mg | 100 | 9 |
| Source | Caffeine Informer | USDA FoodData Central |
Both figures were checked against their source before this page went up: decaf tea against Caffeine Informer (source) and brewed black tea against USDA FoodData Central (source). Brewed drinks and cocoa foods vary by batch, so published figures are averages rather than guarantees.
What the gap means in practice
Brewed black tea is doing the real work here. The practical question is not which number is bigger but whether decaf tea is small enough to ignore in your day: at 4mg per 8 oz cup you would need 100 servings to reach the 400mg reference point, against 9 for brewed black tea.
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If you are chasing the low end on purpose, the bean and the process matter more than the brewer: browse decaf coffee beans on Amazon and check whether the bag says Swiss Water or CO2.
For context, the FDA cites 400mg of caffeine a day as an amount generally not associated with negative effects in healthy adults. Tolerance and health vary, so treat these numbers as information, not advice.
Related reading
- Decaf tea: the full caffeine breakdown
- Brewed black tea: the full caffeine breakdown
- Does decaf have caffeine? Every decaf drink ranked
- Hidden caffeine: the foods and drinks people forget to count
- The verified caffeine database
- Compare any two drinks side by side
FAQ
Does decaf tea or brewed black tea have more caffeine? Brewed black tea, at 47mg per 8 oz cup against 4mg per 8 oz cup for decaf tea.
How much caffeine is in decaf tea? 4mg per 8 oz cup, which works out to about 0.5mg per fl oz. The figure comes from Caffeine Informer.
Is decaf tea caffeine free? No. Decaf tea carries 4mg per 8 oz cup. It is a small amount, but small is not the same as none.
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