How Much Caffeine In London Fog? | Caffeine Math Made Simple

A typical London Fog has 35–70 mg caffeine, based on tea type, steep time, and latte size.

A London Fog is Earl Grey tea with vanilla and milk. It’s a popular pick when you want a tea latte that still has a bit of zip.

The catch: the caffeine isn’t fixed. One shop may steep one bag to order. Another may build it from a stronger tea base. This page shows the usual ranges and a simple way to estimate your cup.

What A London Fog Is

Classic London Fog recipes start with Earl Grey. Earl Grey is black tea flavored with bergamot. The caffeine comes from the tea. Milk and vanilla change taste and texture, not caffeine.

At home, you brew tea in hot water, then add steamed milk and sweetener. In cafes, the tea can be steeped per drink or brewed in batches. That brewing choice is what makes the caffeine swing.

How Much Caffeine In London Fog? Typical Ranges

Most London Fogs land in the tea zone, not the coffee zone. A common range is 35–70 mg of caffeine. It fits a single black-tea serving diluted with milk, plus normal variation in tea and steep time.

Home-Style Cup

With one Earl Grey tea bag and a standard 4–5 minute steep, many mugs land around 35–55 mg. If you brew the tea in a small amount of water and top with milk to reach 12–16 ounces, the caffeine still comes from that same tea bag.

Cafe-Style Cup

Cafes can land lower or higher. Short steeps and extra milk tend to land lower. Two tea bags or a strong tea base can land higher.

Starbucks publishes caffeine for its London Fog Latte; the listing shows 40 mg for a grande.

Some menus also offer a “dirty” London Fog with espresso. If that’s on the menu, ask how many espresso shots are included.

What Moves Caffeine Up Or Down

Four levers do most of the work:

• Tea dose: one bag, two bags, or a heavy scoop of loose leaf.
• Steep time: longer steeps pull more caffeine into the water.
• Tea type: black tea tends to run higher than green tea per serving.
• Recipe scaling: some shops add more tea for larger sizes; others keep one bag and just add more milk.

To anchor your estimate, the U.S. FDA lists typical caffeine amounts for 12-fluid-ounce drinks, including 71 mg for black tea and 37 mg for green tea. Those are “typical” values, but they give you a grounded starting point for a London Fog built from tea. See the caffeine table on the FDA caffeine overview (“Spilling the Beans”).

Why Cup Size Doesn’t Equal Caffeine

People often assume a bigger latte means more caffeine. With coffee drinks, that’s often true because the drink can include more espresso shots. With a London Fog, the size can grow while the tea dose stays the same. Many home recipes use one tea bag no matter the mug size, then add more milk for a smoother sip.

Some cafes do scale tea with size, but not all. A 20-ounce cup can still be built from one tea bag steeped strong, then topped with milk. Another shop may use two bags for that same size. That’s why “small, medium, large” is a weak clue on its own.

Tea Bags, Sachets, And Loose Leaf

Not all “one bag” servings are equal. Some brands use small paper bags with fine cut leaf. Others use pyramid sachets with more room for leaf to unfurl. Loose leaf can swing wider still because the scoop size changes from person to person.

If you’re dialing in your own recipe, weigh your loose leaf once, write it down, then repeat that same dose. You’ll get steadier flavor and a steadier caffeine range from cup to cup.

Hot Vs Iced Builds

Hot London Fogs are usually brewed and served right away. Iced versions are often brewed stronger so the flavor holds up over ice. That stronger tea base can raise caffeine if the shop uses more tea to match the flavor.

If you sip an iced drink slowly, melting ice can make it taste lighter near the end, yet the caffeine in the tea is already in the cup. Taste changes, caffeine doesn’t.

London Fog Style	Tea Setup	Common Caffeine Range
Home, 12 oz	1 Earl Grey bag, 4–5 minute steep	35–55 mg
Home, 16 oz	1 bag, tea concentrate topped with milk	35–55 mg
Home, stronger	2 bags, 4–5 minute steep	70–110 mg
Cafe, light	1 bag, shorter steep, extra milk	25–45 mg
Cafe, standard	1 bag or standard tea base	35–70 mg
Cafe, stronger	2 bags or strong tea base	70–120 mg
Chain label check	Starbucks grande listing	40 mg (listed)
“Dirty” add-on	London Fog + espresso	Tea dose + espresso dose

A Simple Way To Estimate Caffeine At Home

If you brew at home, you can estimate caffeine with three steps: set a baseline, count servings, then adjust for steep time.

Pick A Baseline

Use 50–70 mg as a working range for one brewed serving of black tea. Use a lower range for green tea. If you want one public reference point, the FDA’s typical 12-ounce black tea figure (71 mg) is a useful ceiling for a “full” tea serving. The same page also lists brewed coffee and other drinks: FDA caffeine overview (“Spilling the Beans”).

Count Tea Servings

One tea bag is one serving. Two tea bags is two servings. With loose leaf, follow the brand’s serving size, then treat each serving like one bag.

Adjust For Steep Time

Use a simple multiplier:

• Short steep (2–3 minutes): × 0.8
• Standard steep (4–5 minutes): × 1.0
• Long steep (6+ minutes): × 1.2

Then multiply: (baseline) × (servings) × (multiplier). Milk doesn’t change the result. It only changes taste.

Example math: baseline 60 mg × 1 bag × 1.0 = 60 mg. If you use 2 bags and steep long: 60 × 2 × 1.2 = 144 mg.

How To Get A Number When You’re Ordering Out

When a cafe makes your drink, start by finding the recipe details.

If the shop uses a tea concentrate, ask how it’s made, since concentrate recipes can double the tea dose easily.

• Look for posted caffeine: some chains list it online.
• Ask how they brew it: “one bag or two?” and “how long is the steep?”
• Ask about add-ons: espresso and caffeinated concentrates can change the drink a lot.

Want a simple check at a chain? Use the brand’s nutrition page. Starbucks lists caffeine for the London Fog Latte here: London Fog Latte: Nutrition.

If you track caffeine daily, Health Canada lists recommended maximum daily intakes across age groups and life stages on its Caffeine in foods page.

Daily Caffeine Checks That Keep You In Range

Caffeine totals add up across the day. EFSA cites a 400 mg daily cap for non-pregnant adults and notes 200 mg as a single-dose level for adults in its EFSA caffeine safety opinion. The FDA cites 400 mg per day for most adults and lists typical caffeine ranges for coffee and tea on its FDA caffeine overview.

A simple tally helps. The FDA table lists 113–247 mg for 12-ounce brewed coffee and 71 mg for 12-ounce black tea. One-bag London Fogs often sit below that tea figure; two-bag builds can move closer to coffee.

Caffeine can linger for hours. If sleep gets choppy after an evening tea latte, order decaf or herbal tea.

If you’re pregnant, breastfeeding, or buying caffeine for kids or teens, follow local guidance and ask a licensed clinician for personal advice.

Change You Make	What It Does	Why It Works
Use 1 bag, not 2	Lowers caffeine	Less tea leaf means less caffeine to extract
Steep 3 minutes	Lowers caffeine	Shorter contact time pulls less caffeine
Switch to decaf Earl Grey	Lowers caffeine a lot	Most caffeine is removed, trace remains
Pick a smaller size	May lower caffeine	Some shops use fewer bags in small sizes
Add a second tea bag	Raises caffeine	Two servings of tea doubles the dose
Steep 6+ minutes	Raises caffeine	Longer contact time pulls more caffeine
Add espresso (“dirty”)	Raises caffeine a lot	Espresso adds coffee caffeine on top of tea
Go iced and sip slowly	May feel milder	Ice melt spreads tea over more volume

Ways To Keep A London Fog On The Lower Side

Want the flavor with less caffeine? Try these swaps.

• Use decaf tea: decaf Earl Grey keeps the bergamot note, with far less caffeine than regular black tea.
• Pull the bag early: brew for 2–3 minutes, then add milk and vanilla.
• Skip the “dirty” version: espresso turns a mild tea latte into a stronger caffeinated drink.

Ways To Make It Stronger Without Espresso

If you want more lift but still want the tea profile, raise the tea dose first.

• Use two tea bags or measure more loose leaf.
• Steep longer and taste as you go.
• Order a stronger tea base if the cafe can do it.

Recap Before You Order Or Brew

Keep these points in your back pocket:

• One tea bag plus milk often lands around 35–55 mg.
• Two tea bags or a strong tea base often lands around 70–120 mg.
• Milk changes taste, not caffeine.
• Steep time and tea dose drive the number.

Once you know the tea dose and steep time, you can set the caffeine in your London Fog to match your day. Adjust it later if needed.