How Much Caffeine Is in Decaf Tea?

Decaf Tea Caffeine by Type and Serving Size

Decaf tea caffeine scales with cup size, so a 16 oz travel mug of decaf black tea holds twice the caffeine of a standard 8 oz cup. The 12 oz and 16 oz columns below multiply the published 8 oz figures; they are estimates, not separate measurements.

8 oz figures: Bigelow Tea and The Republic of Tea. Steep time and brand change the result.

Decaffeinated Green Tea vs Regular Green Tea

Decaffeinated green tea carries roughly a tenth or less of the caffeine in regular green tea. The Republic of Tea states that its naturally decaffeinated green tea holds about 2 mg per cup, while regular green tea runs about 20-30 mg depending on steeping time. The Republic of Tea removes caffeine with a high-pressure carbon dioxide (CO2) process.

A 2022 study in Foods found that supercritical CO2 decaffeination removed 98.2% of the caffeine from green tea made from the same fresh leaves as its regular counterpart. The same study reported that decaffeination also shifted other compounds and the sensory profile, so decaf green tea does not taste identical to regular green tea.

Decaf Black Tea Caffeine Content

Decaf black tea falls within the 1-8 mg per 8 oz range Bigelow Tea publishes for decaffeinated tea. In the 2022 Foods study, supercritical CO2 removed 97.1% of the caffeine from black tea, slightly less than the 98.2% removed from green tea. A 16 oz mug of decaf black tea at the top of that range would hold about 16 mg.

What Decaf Tea Means: Decaffeinated vs Caffeine-Free

Decaf tea means a true tea (black, green, white, or oolong from the Camellia sinensis plant) that originally contained caffeine and went through a process to remove most of it. Bigelow Tea states plainly that decaffeinated tea is not completely caffeine-free.

Caffeine-free tea means an herbal infusion made from plants that never contained caffeine. A "decaf" label on tea signals low caffeine; a "caffeine-free" label on a single-ingredient herbal tea signals zero caffeine. The same distinction applies to coffee, covered in the decaf method comparison. For a full breakdown of the two categories and how to read their labels, see decaf tea vs herbal tea.

Is White Tea Decaffeinated?

White tea is not decaffeinated. White tea comes from the same plant as black and green tea, and The Republic of Tea lists it at about 15-20 mg of caffeine per 6 oz serving. Regular white tea is lower in caffeine than many true teas, but a cup still holds several times the caffeine of a cup of decaf tea.

Which Teas Are Truly Caffeine-Free

Truly caffeine-free teas are herbal teas made without Camellia sinensis leaves. Rooibos is one example: The Republic of Tea notes rooibos comes from the South African Aspalathus linearis plant, which contains no caffeine. The same source warns that some rooibos blends add caffeinated tea, so check an herbal blend's ingredient list for black, green, or white tea. Coffee drinkers looking for a zero-caffeine ritual can also see caffeine-free coffee alternatives.

Is Decaf Tea Good for You?

Decaf tea suits people who want the flavor of black or green tea with a small fraction of the caffeine. Decaffeination does change the tea: the 2022 Foods study measured alterations in phytochemical composition and sensory qualities after CO2 decaffeination, so decaf tea is not a chemically identical copy of regular tea. People with a medical reason to avoid all caffeine should choose herbal tea, since decaf tea still contains a few milligrams per cup. If you are deciding how to brew your evening cup, see our comparison of decaf tea bags vs loose leaf, and to keep a decaf cup smooth, read how to brew decaf tea without bitterness.

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