How Much Caffeine Is in a Cup of Black Tea
A cup of black tea generally falls somewhere between 25mg and 110mg of caffeine — a wide range. In the UK specifically, there's a genuine reason most everyday cups land toward the stronger end, and it comes down to how the tea leaf itself is processed.

Why Your Builder's Tea Might Be Stronger Than You Think

Most tea sold in UK supermarkets — including major everyday brands — is processed using a method called CTC, short for Crush, Tear, Curl. Tea leaves are mechanically broken into small, uniform granules, dramatically increasing the surface area exposed to water. The alternative, orthodox processing, keeps leaves whole or lightly rolled, preserving their shape.

Most UK Tea Bags

CTC Processing

Crushed into small granules. Fast, strong infusion in just 2-3 minutes — the reason "builder's tea" brews so quickly and holds up well against milk.

Loose Leaf & Specialty

Orthodox Processing

Leaves kept whole or lightly rolled. Slower to infuse (3-5 minutes), generally milder and more complex in flavour.

A peer-reviewed comparative study published via the National Library of Medicine found CTC-processed tea infusions extracted meaningfully more bioactive compounds, including caffeine, than the equivalent orthodox-processed tea — confirming that processing method genuinely changes what ends up in your cup, not just the taste.

Where Black Tea Sits Next to Familiar Drinks

Numbers in milligrams can be hard to picture. Here's how a standard cup of black tea compares to a few drinks most people already know well.

Can of Cola (330ml) ~34mg

Black Tea (Cup) 25mg – 110mg

Can of Red Bull (250ml) 80mg

0mg 120mg

A UK Rule You've Probably Never Noticed

Under UK regulations, any drink containing more than 150mg of caffeine per litre must display a warning stating it's high in caffeine and not recommended for children or pregnant or breastfeeding women — which is why you'll see this label on energy drinks like Red Bull. A standard cup of black tea, even at the stronger end of its range, sits well below this threshold, which is part of why tea has never needed this kind of labelling.

Try Both Ends of the Range

Compare CTC-style strength against a gentler orthodox blend for yourself.

English Breakfast Loose Leaf Robust Blend

English Breakfast - Loose Leaf

A bold Assam-based blend at the stronger end of the black tea caffeine range.

Earl Grey Loose Leaf Classic Choice

Earl Grey - Loose Leaf

Same black tea base as English Breakfast, with bergamot for a different everyday character.

Read the Full Guide

Tea vs Coffee: Caffeine Content, Health Benefits & Which to Choose →

Related Reading

English Breakfast vs Earl Grey: What's the Difference? →

Shop Our Black Tea Range

From robust everyday blends to delicate orthodox loose leaf.

Shop Coffee & Tea

Frequently Asked Questions

Is Assam tea higher in caffeine than other black teas?
Generally, yes. Assam is typically processed using CTC and tends to sit toward the higher end of the black tea caffeine range, which is one reason it's such a common base for robust everyday blends like English Breakfast.
Does a stronger-tasting cup of tea always mean more caffeine?
Not always, but there's a genuine correlation. Colour and taste strength come from tannins and other compounds extracted alongside caffeine, so a bolder-tasting cup often does carry more caffeine, though the relationship isn't perfectly exact.
How many cups of black tea would reach the UK's 150mg per litre labelling threshold?
A single 250ml cup of black tea, even at the strong end of its range, sits below this per-litre threshold. It's a measure of concentration rather than total daily intake, and everyday tea drinking doesn't come close to triggering it.
Why do supermarket own-brand tea bags all taste similarly strong?
This is largely down to CTC processing being the industry standard for everyday UK tea bags, producing a consistent, robust, fast-brewing cup regardless of brand, since the underlying processing method is broadly similar across most mainstream products.
Does the caffeine content change if I brew a second cup from the same tea bag?
Yes, significantly. Most of the caffeine is extracted in the first minute or two of steeping, so a second infusion from the same bag will contain considerably less caffeine than the first cup.
Is loose leaf orthodox black tea always lower in caffeine than tea bags?
Generally, it tends to be lower due to slower extraction. Still, it's not an absolute rule — the specific tea variety, growing region, and how long you steep it also play a significant role in the final caffeine content.
Tags:
Back to blog