Though coffee is the drink with the greatest source of caffeine, not everyone is down for the bitter taste or adding calories with sugar and sweeteners. Tea doesn't contain as much caffeine as a cup of coffee, but those who prefer tea leaves to coffee beans, you can still get your extra caffeine kick.
Like with coffee, the caffeine levels of tea are affected by different factors. Although black tea, green tea, milk tea, and oolong tea are all "true teas" derived from the same plant, the Camellia sinensis, each drink contains a different level of caffeine.
In an average 8 ounce cup:
While this list is a typical rule, a tea's caffeine levels can change depending on oxidation, brewing and steeping methods, tea grades, and growing methods.
A key influencer in a tea's caffeine levels is oxidation, which is a series of chemical reactions that browns the tea leaves and effects the caffeine, flavor, and aroma of the final drink, according to World of Tea. To achieve oxidation, the tea leaves are rolled to produce cracks so the oxygen reacts with the plant's enzymes. The less a tea is oxidized, the lighter it will be in caffeine, taste, and aroma. In general, black tea is the most oxidized and has the most caffeine, while white tea is the least oxidized and has the least caffeine.
Black tea, such as Earl Grey and English Breakfast, is the most oxidized and flavorful tea, which also makes it the most caffeinated. Each 8-ounce cup of black tea contains between 60 to 90 milligrams of caffeine.
Oolong tea rests between black tea and green tea regarding levels of oxidation, with each cup containing 50-75 mg of caffeine. This type of tea has been linked to lowering cholesterol, stabilizing blood sugar levels, preventing allergies and helping with weight loss. It is traditionally a Chinese tea and still most popular in Southeast Asia.
Green tea is a common choice for tea drinkers who are looking to sip on a relaxing warm cup. It is low on caffeine, containing 35-70 mg per cup, and have a bittersweet taste. There is evidence indicating that drinking green tea can lead to a stronger immune system because the teas, such as Jasmine, are rich in antioxidants.
White tea only undergoes minimal oxidation, if any at all. This means that white tea has significantly less caffeine than its green and black counterparts, with only 30 to 55 mg per 8 oz cup. Along with its lack of caffeine, white teas such as White Peony are also more mild and sweet in taste.
Herbal teas and fruit teas are not classified as "true teas" from the Camellia sinensis plant. Instead, they are a mix of herbs, fruits and flowers.
Herbal teas and fruit teas, including chamomile and peach teas, do not contain any amount of caffeine because they are not made from the same plant most other teas are derived from and therefore do not undergo oxidation. However, because many herbal and fruit teas are made alongside "true teas," sometimes contamination can occur and herbal teas might contain a few milligrams of caffeine.
While in general black tea is the most caffeinated and white tea is the least caffeinated, the way you prepare the tea also plays a part in how much caffeine each cup has. Using more tea leaves, a higher temperature of water and longer brewing time all increase the levels of caffeine in your tea, regardless of type. For example, if you brew a green tea at a higher temperature and for a longer amount of time than an average cup of oolong tea, the green tea can have a higher concentration of caffeine even though oolongs are normally more caffeinated.
Tea grades are categories that are assigned to tea depending on the condition of its leaves. There are whole leaf grades, broken leaf grades, fannings grades and dust grades. As a general rule, broken leaves typically dispense more caffeine into your drink than whole leaves. Teabags hold very broken grades, so they tend to give your tea greater caffeine levels than if you use loose tea leaves. However, using tea bags prevents the tea from reaching their full flavor and aroma potential, so the taste is more subdued than if you were using loose leaves.
Powdered teas, such as Matcha green tea, are particularly high in caffeine. The caffeine content is so high in Matcha that some choose to drink it regularly in place of coffee because, typically, the caffeine levels in Matcha are double the levels of regular green tea. This is because Matcha is made from crushed leaves, not just an infusion of leaves and hot water. By drinking Matcha, you are consuming entire tea leaves, so you are drinking all of the caffeine it contains instead of a fraction. Matcha is also shade-grown, which influences its caffeine levels (read more on shade-grown teas below).
It's not all about how you steep your tea -- a drink's caffeine levels are also influenced from how the leaves are grown. Shade-grown teas like Matcha have higher levels of caffeine because of shifts in chlorophyll and amino acids that take place as the plants are shaded from sunlight before harvest.