Updated: Mar 11
Just how much caffeine is in a cup of tea? For a long time it was said that black tea was high in caffeine, green tea was low, and others were in between - that turns out not to be the case. Caffeine level depends on how the tea is picked, how it’s processed, and how it’s brewed, in addition to other factors. While we may not be able to assign a specific number to a cup of tea, we can still get a sense of relative caffeine levels. For one thing, any tea will fall between 1/2 and 1/4 the caffeine of a cup of coffee.
To understand where different teas land in that range, we need to understand the purpose of caffeine to the tea plant. Caffeine, in its raw form, is very bitter. That bitterness works to keep insects away - they don’t like the bitter taste any more than we do! Teas grown at higher elevations, where it’s colder and less exposed to insects, tend to have lower amounts of caffeine. For example, our Fairy Fire Oolong is a high mountain grown oolong, so it has ‘below average’ caffeine.
Additionally, the tea plant is interested in protecting the most important and vulnerable growth - the budding leaves. Older leaves are tougher and stronger, so they have less to fear from insects. As a result, the buds have higher caffeine than the older leaves. Some teas, like Silver Spring, are made entirely from buds and thus relatively high in caffeine. On the other hand, Shou Mei, like our Wild White Longevity, is made from older leaves, and therefore below average caffeine, despite both being White Teas. Stems have the lowest of all, which makes our Cookie-cha - made mostly from stems - very low in caffeine!
When it comes to processing of tea leaves and types of tea, there’s very little that affects caffeine. Oxidation, the spectrum between green and black tea, does not change the caffeine content of the leaf. One thing that does is roasting. Heavily roasted teas have less caffeine than the same unroasted leaves would. Our Cookie-cha is not only made from stems, it's also roasted, making it one of the lowest caffeine teas you can get.
But the biggest factor affecting caffeine content is how the tea is brewed. Caffeine, like other chemical compounds in the leaf, is extracted over time during brewing. You would have to boil the tea for 15 minutes to extract all of the caffeine in the leaf (and you'd have a very bitter cup!).
How strong you like your tea determines how much caffeine you’re getting. Re-brewing the same leaves leads to lower caffeine each brew. You can control caffeine content by using lower temperature water, brewing for shorter times, or taking an extra long 'wake up' when Waking Up the Tea.
A tea like matcha - powdered green tea - has the highest caffeine of all. When you drink matcha, you’re consuming the whole leaf, rather than an extraction. Similarly, steamed teas, like Sencha, have above average caffeine. This is due to the steaming process causing the leaves to break down slightly, so that small particles of leaf make it into the brewed tea. Many Japanese green teas turn out to be relatively high in caffeine, while a high mountain grown, heavily roasted oolong (like our Water Fairy) turns out to be relatively low.
In the end, it’s best to remember that all tea has a relatively low level of caffeine compared to coffee, while exact amounts vary cup to cup. But we've assigned relative caffeine levels to the teas in our shop, using this ranking system: