A Starbucks London Fog Tea Latte has 40mg of caffeine, and it is 40mg at every size, from tall to venti, per the Starbucks nutrition listing. Make it at home with Earl Grey bags and the number depends entirely on how many bags you steep: roughly 30 to 60mg per bag for a standard black-tea Earl Grey, per Bigelow's caffeine guide.
Why the Starbucks number stays flat and yours won't
The London Fog is an Earl Grey tea latte, no espresso, so all the caffeine comes from the tea. Starbucks publishes a single 40mg figure across sizes because the drink is built on their Earl Grey sachet plus steamed milk, and the published value does not scale up the way the cup does. That flat number is worth knowing if you order a venti expecting a bigger hit. You are not getting one on paper.
Behind the counter the recipe card actually tells a different story than the label. Short and tall London Fogs get one Earl Grey bag, grande and venti get two, so the real caffeine in a larger cup is closer to double even though the nutrition line reads 40mg for all of them. Steep time matters too. A bag that sits longer in hot water gives up more caffeine, which is why two identical drinks can feel different. Treat the 40mg as Starbucks' stated figure, not a promise of what is in your specific cup.
At home you control both variables. One bag of a standard Earl Grey lands in the 30 to 60mg range that Bigelow gives for its black teas per 8oz cup. General Earl Grey estimates run a bit wider, around 40 to 70mg per cup, since the black-tea base and steep time vary by brand. Use two bags, the way Starbucks does for a grande, and you are looking at roughly 60 to 120mg. That is the honest range, and it is why a homemade London Fog can easily out-caffeinate the cafe version.
London Fog caffeine by version
| Version | Caffeine | Source |
|---|---|---|
| Starbucks London Fog, all sizes (tall to venti) | 40mg | Starbucks nutrition |
| Homemade, 1 Earl Grey bag (black-tea base) | ~30-60mg | Bigelow caffeine guide |
| Homemade, 2 Earl Grey bags (grande-style) | ~60-120mg | Bigelow, doubled |
| Earl Grey per 8oz cup, general estimate | ~40-70mg | Compiled tea charts |
The takeaway: the branded drink is a low-caffeine option at a steady 40mg, while a homemade Earl Grey latte can be anywhere from mild to nearly triple that depending on how many bags you use and how long they steep. If you want a gentle afternoon cup, one bag and a short steep keeps you at the low end.
The iced London Fog uses the same Earl Grey base, so its caffeine tracks the hot version rather than changing on its own. If you want to nudge the number down without switching drinks, ask for a decaf Earl Grey bag where available, or steep your home version for two minutes instead of five. To push it up, add a second bag or extend the steep. None of that changes the milk or the vanilla, just the tea strength, which is the only caffeine source in the cup.
One more practical note for anyone tracking intake: because a London Fog is milk-forward and half tea by volume, it drinks smoother than a straight cup of black tea at the same caffeine level. That is a feature, not a loophole. The 40mg is real, it just arrives with less of the tannic bite, which is exactly why the drink is an easy afternoon order when you do not want a full coffee.
For context, the FDA cites 400mg of caffeine a day as an amount generally not associated with negative effects in healthy adults. How caffeine affects you depends on your own tolerance and health, so treat these numbers as information, not advice.
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Related caffeine numbers
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- The full Barista Life caffeine database for every drink number in one place.
FAQ
Does a London Fog have caffeine? Yes. It is an Earl Grey tea latte with no coffee, and Starbucks lists 40mg of caffeine for every size, all of it from the black-tea base.
Does a bigger London Fog have more caffeine? On Starbucks' label, no, it stays 40mg from tall to venti. In practice grande and venti use two Earl Grey bags versus one for short and tall, so the larger sizes likely carry more caffeine than the number suggests.
How much caffeine is in a homemade Earl Grey latte? Around 30 to 60mg for one bag per Bigelow's black-tea range, or roughly 60 to 120mg if you use two bags. Longer steeping pushes it toward the high end.