How much caffeine is usually in a tea bag? A detailed guide

January 9, 2026 •

4 min read

An average black tea bag contains approximately 40 to 70 milligrams of caffeine, while green tea offers a milder 20 to 45 milligrams per 8-ounce serving. However, this is not a one-size-fits-all answer, as the question of how much caffeine is usually in a tea bag depends on numerous variables, including the type of tea, processing, and brewing method.

Quick Summary

The caffeine content in a standard tea bag varies significantly by tea type, with black tea typically containing more than green, white, or oolong tea. Brewing duration, water temperature, and tea leaf particle size all influence the final caffeine level in your cup.

Key Points

Black Tea: A typical black tea bag contains 40–70 mg of caffeine per 8 oz cup, making it the most caffeinated of the standard true teas.
Green Tea: Green tea bags usually offer a more moderate caffeine level of 20–45 mg per 8 oz serving.
Herbal Tea: True herbal teas are naturally caffeine-free, offering a stimulant-free beverage option.
Leaf Size and Brewing: The fine, broken leaves in tea bags allow for quicker caffeine extraction, which can result in a higher caffeine concentration than some loose-leaf teas under the same brewing conditions.
Steeping Time and Temperature: Longer steep times and higher water temperatures increase the amount of caffeine extracted from any tea bag.
L-theanine's Influence: The amino acid L-theanine in tea provides a more gradual, sustained energy boost and helps to counteract the jitters that caffeine can cause.

Average Caffeine Content by Tea Type

While it's difficult to give a single number, standard tea bags generally fall within certain ranges depending on the tea type. True teas, which come from the Camellia sinensis plant, all contain caffeine, with levels influenced by their processing. Herbal infusions, made from other plants, are naturally caffeine-free unless otherwise specified.

Black Tea

Black tea is known for having a higher caffeine content than other true teas due to its full oxidation process. A standard tea bag of black tea, like English Breakfast or Earl Grey, can yield between 40 and 70 mg of caffeine in an 8-ounce cup. However, bolder types like Assam can reach the higher end of this spectrum.

Green Tea

Green tea bags typically contain less caffeine than black tea, with an average range of 20 to 45 mg per 8-ounce serving. This lower level is due to green tea leaves being unoxidized. Varieties like Matcha, which involves consuming the powdered whole leaf, will have a much higher concentration of caffeine.

Oolong Tea

Partially oxidized, Oolong tea falls in the middle of the caffeine scale, generally providing 30 to 50 mg per serving. The wide range is a result of the varied oxidation processes used for different oolong styles.

White Tea

White tea, made from young tea leaves and buds, is minimally processed and usually has the lowest caffeine content of all true teas, often ranging from 15 to 30 mg per cup. However, some specialty white teas made from buds can have higher levels.

Herbal Tea

Herbal teas (or tisanes), which are not made from the Camellia sinensis plant, are typically caffeine-free. Popular varieties include chamomile, peppermint, and rooibos. It's important to check the ingredients, as some herbal blends may include true tea leaves for flavor or added effect.

Factors Influencing a Tea Bag's Caffeine Level

Even within the same tea type, the amount of caffeine can vary significantly based on several factors.

Brewing Time: The longer you steep your tea bag, the more caffeine is released into the water. A one-minute steep will extract less caffeine than a five-minute steep.
Water Temperature: Hotter water extracts more caffeine from the tea leaves more quickly. Boiling water will result in a higher caffeine content than brewing with cooler water.
Leaf Particle Size: The crushed leaves found inside conventional tea bags (often referred to as 'fannings' or 'dust') have a larger total surface area compared to whole loose leaves. This allows for a more rapid and robust caffeine extraction, which is why a cup brewed from a tea bag can sometimes contain more caffeine than a loose-leaf version of the same tea.
Tea Plant Variety: The two main varieties of the Camellia sinensis plant have differing caffeine levels. Camellia sinensis var. assamica, native to India, generally has higher caffeine content than Camellia sinensis var. sinensis, native to China.
Age of Leaves: Younger, more recently harvested leaves and buds typically contain higher levels of caffeine than older, more mature leaves.

Comparison Table: Caffeine in Tea Bags vs. Other Beverages


Beverage Type (8 oz serving)	Typical Caffeine Range (mg)	Notes
Brewed Coffee	95–200	Drip coffee contains significantly more caffeine than most tea bags.
Black Tea Bag	40–70	Moderate caffeine level, often described as about half of a cup of coffee.
Oolong Tea Bag	30–50	Falls between black and green tea in caffeine content.
Green Tea Bag	20–45	Lower caffeine content provides a milder energy boost.
White Tea Bag	15–30	The lowest caffeine of the true teas.
Herbal Tea (e.g., Chamomile)	0	Naturally caffeine-free infusions.
Energy Drink (16 oz can)	72–80+	A much higher and more concentrated caffeine dose.

The L-theanine Effect

It's also worth noting the presence of L-theanine, an amino acid found in tea leaves, which works with caffeine to create a different kind of energizing effect than coffee. L-theanine promotes relaxation without drowsiness and can lead to a more focused, sustained energy boost, minimizing the jitters often associated with coffee. This synergistic relationship means that even with less caffeine, tea can provide a calming, yet alert, experience.

Conclusion

While a definitive answer to how much caffeine is usually in a tea bag is complex due to multiple variables, a reliable estimate is between 15 and 70 mg, depending on the tea type. Black tea and oolong tend to have higher levels, while green and white teas offer a more moderate amount. The fineness of the tea leaves in bags often leads to a faster and more complete caffeine extraction compared to loose-leaf varieties. Ultimately, by controlling factors like steep time and water temperature, tea drinkers have a greater ability to manage their caffeine intake and tailor their cup to their preferences.

This article provides general information. Individual products may vary. For specific health advice, always consult a healthcare professional. For more information on the complexities of tea, a deeper dive into the science of tea brewing and its effects can be found through various research sources.

Frequently Asked Questions

A standard tea bag typically contains significantly less caffeine than an 8-ounce cup of brewed coffee. While a cup of black tea may have 40-70 mg, brewed coffee often has 95-200 mg.

Among the common true teas, black tea bags generally have the highest caffeine content, ranging from 40 to 70 mg per 8-ounce cup. Varieties like Assam black tea can be particularly potent.

No, not all tea bags contain caffeine. Only true teas made from the Camellia sinensis plant contain natural caffeine. Herbal teas, or tisanes, are naturally caffeine-free.

Yes, steeping a tea bag for a shorter duration, such as 1 to 2 minutes, will result in less caffeine being extracted into your cup compared to a longer steeping time.

The finely ground leaves in conventional tea bags generally extract caffeine more quickly and often lead to a more caffeinated brew than whole loose leaves under the same brewing conditions.

Hotter water extracts caffeine more efficiently from a tea bag. Therefore, brewing with hotter water will result in a higher caffeine level in your cup.

Tea contains the amino acid L-theanine, which promotes relaxation and slows the absorption of caffeine. This leads to a smoother, more sustained energy boost and fewer jitters compared to the rapid caffeine rush from coffee.