The honest answer is around 2mg per cup. Sometimes more, occasionally less, almost never zero. That is the figure the British Heart Foundation, Twinings, Teapigs and the USDA all agree on, give or take.
The more interesting question is what that means in practice, and why none of the existing UK page-one results telling you “2mg per cup” can also tell you which decaf tea on your supermarket shelf is which, made how, and whether the leftover caffeine matters.
This is the version that answers the second question.
How much caffeine is in decaf tea
A 200ml cup of UK decaf black tea typically contains 2 to 5mg of caffeine. Decaf green tea sits in a wider 1 to 8mg range. Regular black tea, for contrast, has around 50mg per 200ml cup, or roughly 75mg in a full mug. Decaffeination removes 96 to 99% of the caffeine in the leaf. It does not remove all of it.
Why decaf tea isn’t caffeine-free
Twinings holds residual caffeine in its dry decaf tea leaves below 0.1% by weight, and PG Tips publishes below 0.2% in finished tea. Decaffeination processes leave a deliberate buffer below those brand thresholds, so the next batch off a slightly different harvest doesn’t fail testing. The residual you taste, all 2mg or so of it, is that buffer.
There is also a category distinction worth being clear about. Decaffeinated tea is true tea, Camellia sinensis, with most of the caffeine removed. Caffeine-free tea is a herbal infusion: rooibos, chamomile, peppermint, hibiscus, ginger, honeybush, fruit blends. Strictly, those are tisanes. They never contained any caffeine in the first place.
If your goal is zero caffeine, you want a tisane. If your goal is something that drinks like English Breakfast or a green tea without the buzz, you want decaf.
Pukka refuses to sell decaffeinated tea on principle. Their range is naturally caffeine-free, on the grounds that the decaffeination process “alters a plant’s natural chemistry” and the solvent-based methods don’t sit with their organic principles. You don’t have to agree with the framing to find it useful. It cleanly marks the line.
One footnote. Caffeine is not the only stimulant in tea. Theobromine and theophylline, both mild methylxanthines, are still present after decaffeination, alongside L-theanine, which is calming. The mix is part of why a decaf cuppa behaves differently to a decaf coffee at low doses.
How decaf tea is made: the four main methods
Four mainstream processes are used to take caffeine out of tea leaves. Two use no solvent. Two do.
CO₂ (supercritical carbon dioxide) extraction. High-pressure CO₂ binds preferentially to caffeine and removes it, leaving most flavour compounds intact. No organic solvent involved. The Soil Association will certify it for organic tea. Clipper uses it across every decaf they sell, Teapigs uses it, Brew Tea Co uses it. The specialty-grade option.
Ethyl acetate. A solvent-based method, but ethyl acetate occurs naturally in fruit and in tea itself, which is why packaging often calls this “naturally decaffeinated”. Leaves are moistened, the solvent extracts the caffeine, the solvent is evaporated off in drying. Tetley uses this. Brew Tea Co, who use CO₂, describe ethyl acetate as “pretty harsh” on flavour. You may agree once you’ve tasted it.
Methylene chloride (dichloromethane). Another solvent method, and the cheapest at industrial scale. UK and EU food law caps residue at 5 parts per million on the finished product. Methylene chloride is classified as a probable carcinogen on inhalation and dermal exposure, which is a different exposure profile from drinking trace residues in tea, but the consumer optics have done the work either way. PG Tips’ decaf is the most prominent UK example still on supermarket shelves.
Water process. Leaves are soaked, the water dissolves caffeine and flavour, the water passes through activated carbon that binds caffeine but not flavour, and the leaves are re-soaked to recover flavour. Common in coffee (Swiss Water). Less common in tea, partly because the back-and-forth handling tends to flatten the cup.
No top-ten UK result pairs all four methods with the brands actually using them. So.
Decaf tea vs decaf coffee, regular tea and coffee
The numbers in one place, per typical UK serving.
| Drink | Caffeine per serving |
|---|---|
| Filter coffee (mug) | ~140mg |
| Instant coffee (mug) | ~100mg |
| Energy drink (250ml can) | ~80mg |
| Espresso (single shot) | ~75mg |
| Regular black tea (mug) | ~75mg |
| Regular black tea (200ml cup) | ~50mg |
| Cola (330ml can) | ~40mg |
| Green tea (200ml cup) | ~25 to 30 mg |
| Decaf coffee (cup) | 2 to 15 mg |
| Decaf black tea (200ml cup) | 2 to 5 mg |
| Decaf green tea (200ml cup) | 1 to 8 mg |
A couple of those surprise people. Decaf green tea is not reliably lower than decaf black, even though regular green has less caffeine than regular black. USDA data puts decaf black at 2.4mg per 8 fl oz; surveys of decaf green commonly land between 2 and 10mg. The gap between regular green and regular black doesn’t survive the decaffeination wash. So choose your decaf on flavour and brand, not on the assumption that green will be lower.
Decaf tea is also generally lower in residual caffeine than decaf coffee, because regular tea starts with less caffeine than regular coffee. Stripping 98% off a small number gets you a smaller number.
Is the leftover caffeine a problem
For most people, no. For some people, sometimes, yes.
Pregnancy. The NHS limit is 200mg of caffeine per day during pregnancy. Decaf tea contributes 2 to 5mg per cup. You would have to drink forty cups in a day for decaf alone to put you anywhere near the limit. Tommy’s, the UK pregnancy charity, explicitly recommends decaf tea and coffee as low-caffeine swaps. NHS England’s regional infographics go further and suggest decaf is the preferred option, on the basis that there is no known safe lower bound. The maths on decaf tea is comfortably inside the guidance either way.
Two qualifiers. Caffeine from other sources counts toward the 200mg, so a couple of regular coffees plus a decaf tea is still adding up. And not every herbal tea is pregnancy-safe by default. Some detox and cleanse blends, raspberry leaf in the first two trimesters, and a handful of others have their own guidance. Check the box, not the category.
Caffeine sensitivity and sleep. A residual 2 to 5mg sits well below the threshold most adults notice. If you are at the highly sensitive end, the practical wellness press advice is to allow 2 to 3 hours between a decaf cup and bed, or switch to a naturally caffeine-free tisane for the evening cup. The L-theanine in true tea does some of the offsetting work even when caffeine is present, which is why a decaf English Breakfast at 9pm is, for most sleepers, fine.
The BHF puts general adult caffeine safety at up to 400mg per day. At that ceiling, decaf tea is not the variable to worry about.
UK decaf tea brands compared
The thing no other UK page-one result publishes. Method by brand, plus residual caffeine where the brand itself states one. Brands that don’t publish a number are flagged, not invented.
| Brand | Method | Residual caffeine (published) | Notes |
|---|---|---|---|
| Twinings | CO₂ / water and steam | ~3mg per teabag; under 0.1% in dry leaf | Range spans Decaf English Breakfast, Decaf Earl Grey, Decaf Green, Decaf Lady Grey |
| Clipper | CO₂ | Not published as a number | Soil Association organic and Fairtrade |
| Teapigs | CO₂ | ~2mg per cup; over 98% removed | Decaf English Breakfast (Kenyan and Ceylon blend) |
| Yorkshire Tea | Reported as CO₂ in current sources | Not published | Method isn’t on the live product page. Verify with Taylors before buying on method grounds |
| PG Tips | Methylene chloride | Under 0.2% caffeine in finished tea | Residue capped under UK law at 5 parts per million. The most consumer-sensitive choice in the table |
| Tetley | Water/steam then ethyl acetate | Not published | Supermarket “naturally decaffeinated” labelling usually means this |
| Brew Tea Co | CO₂ | Not published as a number | Editorially opposed to solvent methods. Specialty-grade |
| Pukka | Does not sell decaffeinated tea | n/a | Range is naturally caffeine-free herbal infusions only |
Two things worth flagging from that table that no other UK page does.
One. Method does not track price. Clipper, Teapigs and Brew Tea Co all use CO₂, the same method specialty coffee uses, and Clipper sits in supermarket aisles at near-supermarket prices.
Two. PG Tips uses the only consumer-sensitive method in the table. Residue is regulated and accepted by UK food law. Campaigners argue for precaution. The EU and UK regulators signed off years ago. Pick your side, but pick it informed.
How to choose a truly low-caffeine cup
If you want zero caffeine, pick a tisane. Rooibos, chamomile, peppermint, hibiscus, ginger. Not decaf.
If you want true tea (black, green, white) with the caffeine removed, look for CO₂ on the box. Clipper, Teapigs and Brew Tea Co all label this clearly. Twinings’ wider range mostly uses CO₂ or water and steam.
If you are avoiding solvents specifically, CO₂ or water process. Skip “naturally decaffeinated” wording on the box; it usually means ethyl acetate.
If you are buying supermarket-cheap and don’t mind ethyl acetate, Tetley and most own-brand decafs.
If you are pregnant or caffeine-sensitive, decaf tea (2 to 5mg) is comfortably inside any UK health guideline. So is a caffeine-free tisane, with the boring caveat of checking that a specific herbal is pregnancy-safe before getting through a pot a day.
One last word on the home-brew myths. The “30-second pre-rinse” trick that allegedly decaffeinates a regular tea bag at home removes around 9% of the caffeine. Not 80%. Not 90%. Commercial decaf removes 96 to 99%. There is no kitchen equivalent.
Most readers here came for the decaf coffee, where the spread between methods is wider and the buying gap is bigger. The decaffeination methods hub covers Swiss Water, CO₂ and chemical processes for coffee, which overlap heavily with the four methods used in tea.