Most people assume that coffee delivers a bigger caffeine hit than tea, and for a standard cup in the UK, that is generally correct. While the raw leaf of the tea plant contains more caffeine than the raw coffee bean by weight, the brewing process and amount used per serving mean that a typical mug of coffee has a significantly higher caffeine content. Understanding the various factors that influence these levels is key to knowing what's really in your cup.
The Brewing Process: A Crucial Difference
The way tea and coffee are prepared is the primary reason for the difference in caffeine levels. Coffee is typically brewed using more ground product and higher water temperatures than tea, which extracts a higher concentration of caffeine from the beans. Tea leaves are usually steeped, and many people steep for a shorter time, resulting in less caffeine extraction. For example, a black tea steeped for just one minute will contain much less caffeine than one steeped for five minutes.
- Coffee's high extraction: Hotter water and a greater quantity of grounds maximise caffeine extraction. A standard filter coffee, a common sight in UK offices and homes, exemplifies this with its robust caffeine content.
- Tea's varied extraction: The caffeine in tea is absorbed more slowly due to the presence of an amino acid called L-theanine, which provides a smoother, longer-lasting energy boost compared to coffee's quicker, more intense kick.
- Loose leaf vs. tea bags: The surface area of tea leaves plays a role. Crushed leaves in a tea bag release their caffeine more quickly than loose-leaf tea, affecting the final caffeine concentration.
Instant vs. Brewed: Not All Coffee is Equal
Within the coffee category itself, there are major differences. Instant coffee, a staple in many UK households, generally contains less caffeine than its freshly brewed filter counterpart. However, both still typically outrank a standard cup of tea.
- Filter Coffee: Around 95mg per 240ml cup on average.
- Instant Coffee: Approximately 30-90mg per cup, with brand variations.
- Espresso: While a single shot (30ml) has around 63mg, many popular UK coffee shop milky drinks use a double shot, bringing the caffeine content to around 125mg or more.
The Tea Spectrum: A World Beyond Black
Tea is far from uniform. The type of tea and its processing greatly impact its caffeine content. Black tea, such as English Breakfast, contains the most caffeine among standard teas, while green and white teas have less. Herbal teas are generally caffeine-free, as they are not made from the Camellia sinensis plant.
- Black Tea: English Breakfast tea typically contains 47-90mg of caffeine per cup, but an average black tea with milk may be closer to 47mg.
- Green Tea: A cup of green tea contains, on average, less caffeine than black tea, around 33mg.
- Matcha Tea: Matcha, a powdered green tea, is a notable exception. Because you consume the entire tea leaf, it contains a significant amount of caffeine—around 70mg per 100ml in some cases.
Comparative Caffeine Content in the UK
| Beverage Type | Approximate Caffeine per Serving (UK) | Notes |
|---|---|---|
| Brewed/Filter Coffee (240ml) | 95mg (Average) | Higher amounts of coffee grounds and hotter water temperature increase extraction. |
| Instant Coffee (240ml) | 30-90mg | Less concentrated than brewed coffee but more convenient. |
| Espresso (single shot, 30ml) | 63mg | A double shot in a latte or cappuccino can easily double this amount. |
| Black Tea (mug) | 75mg (FSA estimate) | The steeping time is a critical factor for caffeine release. |
| Green Tea (mug) | 33mg (Average) | Generally lower caffeine than black tea. |
| Matcha Tea (powder) | 70mg per 100ml | Exceptionally high caffeine for a tea due to consuming the whole leaf. |
The Health Effects and Energy Boost
Beyond just the quantity of caffeine, the effect on the body also differs. Coffee provides a rapid, sometimes jittery, boost of energy. In contrast, the combination of caffeine and L-theanine in tea results in a calmer, more sustained sense of alertness. For individuals with a higher sensitivity to caffeine, tea can be a better option to avoid side effects like palpitations or anxiety. Both coffee and tea are rich in antioxidants, offering various health benefits, and moderate consumption is considered safe for most healthy adults, with the NHS and FSA setting guidelines for daily intake.
Conclusion
In the UK, coffee generally contains more caffeine per cup than tea, with the average brewed coffee providing about double the amount of a standard mug of black tea. However, the exact caffeine content is highly dependent on factors such as the type of bean or leaf, the brewing method, and the serving size. From a high-caffeine filter coffee to a low-caffeine instant blend or a more mellow cup of green tea, the choice comes down to personal preference and your desired energy level. For those seeking a powerful and quick boost, coffee is the clear winner, while tea offers a smoother, more gentle lift throughout the day.
For more detailed guidance on safe caffeine consumption levels, you can consult the official recommendations from the UK's Food Standards Agency.
Summary of Key Differences
- Source Matters: On a dry weight basis, tea leaves have more caffeine than coffee beans, but brewing methods reverse this outcome in the final cup.
- Extraction Differences: The hotter water and higher quantity of coffee grounds used in brewing lead to greater caffeine extraction compared to steeping tea.
- Energy Profile: Coffee provides a fast, bold energy kick, while tea, with its L-theanine content, offers a calmer, more sustained boost.
- Variety is Key: Within each beverage, caffeine content varies widely; from potent espresso and matcha to lower-caffeine instant coffee and green tea.
- Personal Sensitivity: Individual response to caffeine can vary, with some people experiencing side effects more readily from the higher levels in coffee.
Which beverage is better for your health?
- Both are beneficial: Both coffee and tea are rich in antioxidants and linked to health benefits, with moderate consumption considered safe for most people.
- Consider additives: The health impact is often more influenced by additives like sugar, milk, and cream, rather than the caffeine itself.
- Listen to your body: If you're sensitive to caffeine, the lower dose and L-theanine content of tea may be a better choice for maintaining alertness without jitters.
