Oolong Tea: Caffeine Levels Explained

A 240 ml cup of oolong tea has 37 mg of caffeine.

• One 240 ml cup of oolong tea contains 37 mg of caffeine (≈15.4 mg/100 ml).
• Oolong has about 10 mg less caffeine per cup than typical black tea (47 mg/240 ml) and 9 mg more than green tea (28 mg/240 ml).
• Population-average caffeine half-life is 5.7 hours; from 37 mg, ~18.5 mg remains after 5.7 hours and ~8.5 mg after 12 hours.
• FDA daily limit for most healthy adults is 400 mg; pregnancy guidance suggests ~200 mg/day, and the American Academy of Pediatrics discourages routine caffeine for adolescents.

Does oolong tea contain caffeine?

Yes. Oolong is a true tea made from Camellia sinensis leaves and therefore contains caffeine. The dataset value used here represents a typical prepared cup: 240 ml of oolong tea has 37 mg of caffeine (15.4 mg per 100 ml). That places oolong between green and black tea in typical caffeine content.

Caffeine levels in different oolong varieties

There is no single fixed number for every oolong. The 37 mg per 240 ml value is an average for a standard cup. Less-oxidized, lighter oolongs (closer to green tea) and shorter steeps produce less caffeine per cup; darker, more heavily processed oolongs and stronger brews will yield more. Commercial bottled oolongs and tea bags can also vary.

Practical serving examples

How oolong compares to other teas and coffee

Using the dataset values: a standard oolong cup (37 mg) contains about 39% of the caffeine in a 240 ml cup of drip coffee (96 mg) and roughly half the caffeine of matcha (70 mg per 240 ml). Compared with black tea (47 mg) it’s modestly lower, and notably higher than white tea (16 mg) and herbal infusions (0 mg).

Factors that change oolong's caffeine content

Caffeine per cup depends on leaf mass, leaf particle size, water temperature, steep time and whether you consume infused leaves (as with matcha). Higher leaf-to-water ratios and longer steeps extract more caffeine. Commercial lab values (like those in USDA FoodData Central) represent typical home preparations; individual brews can differ substantially.

How long oolong caffeine lasts in your body

Pharmacokinetically, caffeine follows exponential elimination. The population-average half-life is about 5.7 hours; after each 5.7-hour interval the caffeine quantity roughly halves. Here are approximate remaining amounts from a single 37 mg cup.

Individual half-life varies with age, pregnancy, liver function, smoking (which speeds clearance), and some medications. Sources for population guidance include FDA and peer-reviewed pharmacology summaries; USDA FoodData Central is the reference for beverage nutrient values.

Health considerations and safe limits

For most healthy adults the U.S. FDA notes 400 mg/day as a non-harmful upper bound; European Food Safety Authority and Mayo Clinic offer similar guidance. For pregnant people, many authorities recommend keeping caffeine near or below 200 mg/day. The American Academy of Pediatrics discourages routine caffeine use in adolescents. If you have anxiety, certain heart conditions, or take interacting medications, discuss intake with your clinician.

Because oolong is relatively low in caffeine versus coffee and many energy drinks, it is a practical choice when you want a milder stimulant effect. Track cumulative daily intake using a tool like CoffeeLog to stay within recommended limits, especially if you also drink coffee, matcha, or energy drinks.

Practical tips

• Shorten steep time or reduce leaf mass to lower caffeine in a cup.
• Choose white tea or herbal infusions if you want essentially zero caffeine.
• Avoid late-afternoon oolong if you are sensitive to sleep disruption; even 8–12 mg of remaining caffeine can affect sleep in sensitive people.

This page summarizes typical values; for exact labeling consult product-specific nutrition data or USDA FoodData Central. If you have medical concerns, consult a healthcare professional before changing caffeine-related habits.

If I drink a second cup of oolong three hours after the first, how much caffeine will be in my body?

A 240 ml cup of oolong contains 37 mg of caffeine (per USDA FoodData Central); after 3 hours about 37 × 0.5^(3/5.7) ≈ 25.5 mg remains using a population-average half-life of 5.7 hours (model used here; Drake et al., J Clin Sleep Med, 2013), so adding a fresh 37 mg at hour 3 yields ≈62.5 mg total in the body immediately after the second cup.

Pharmacokinetic superposition is adding the remaining amount from earlier doses to any new dose at the time the new dose is taken.

Practical implication: two modest oolong cups spaced by three hours produce an internal caffeine load (≈62.5 mg) similar to roughly two-thirds of a single 240 ml drip coffee (96 mg) when compared directly using dataset values; see the side-by-side comparison tool for quick conversions at caffeine comparisons.

How much does a late-afternoon oolong affect my sleep?

A single 240 ml oolong leaves about 37 × 0.5^(6/5.7) ≈ 17.8 mg at 6 hours after drinking when using a 5.7-hour half-life model (Drake et al., J Clin Sleep Med, 2013), and Drake et al. showed that a 400 mg caffeine dose taken 6 hours before bedtime reduced objective sleep time by more than one hour (Drake et al., 2013).

Sleep-sensitive window is the interval before bedtime during which consumed caffeine can measurably shorten or degrade sleep.

Put another way, the remaining ~17.8 mg from one oolong at 6 hours equals about 4.5% of the 400 mg reference dose used in Drake et al.; the practical takeaway is that if you are sleep-sensitive you should avoid oolong within several hours of bed—use the Last Cup Before Bed tool to estimate timing relative to your bedtime.

How do I calculate the caffeine left from my last oolong cup?

Use the first-order elimination formula Remaining (mg) = Dose × 0.5^(hours / 5.7); for a 240 ml oolong (37 mg per USDA FoodData Central) that gives 37 × 0.5^(t/5.7) mg remaining after t hours using a 5.7-hour population half-life (Drake et al., 2013).

First-order elimination is an exponential decrease where the quantity remaining after time t equals the starting dose multiplied by 0.5 raised to the power (t divided by the half-life).

Worked examples: at t=1 hour remaining ≈ 37 × 0.5^(1/5.7) = 33.9 mg; at t=3 hours remaining ≈ 25.5 mg; at t=6 hours remaining ≈ 17.8 mg; at t=12 hours remaining ≈ 8.5 mg — each numeric result here uses the 5.7-hour half-life model (Drake et al., 2013) and the 37 mg cup value from USDA FoodData Central.

If you prefer an automated calculator, enter your last-drink time and amount into the Caffeine Half-Life Calculator on TrackCaffeine to get live mg-remaining estimates.

Can drinking oolong every day lead to tolerance or withdrawal, and how long do symptoms last?

Regular daily caffeine intake from oolong can produce tolerance to some stimulant effects within days to weeks and can produce a withdrawal syndrome when stopped; withdrawal typically begins 12–24 hours after cessation, peaks at 24–48 hours, and often resolves within about 1–2 weeks (Mayo Clinic; NIH Office of Dietary Supplements informational summaries).

Withdrawal is a predictable syndrome of headaches, fatigue, low mood and reduced alertness that follows abrupt cessation of regular caffeine use.

What that means for oolong drinkers: a single 37 mg cup contributes to daily exposure but by itself is unlikely to create a strong physical dependence; however, three or more cups per day (3 × 37 mg = 111 mg) combined with other sources (coffee, energy drinks, chocolate) can raise baseline exposure enough that stopping suddenly may cause withdrawal — compare cumulative exposure against recommended bounds with the Safe Daily Limit tool and read practical management tips in our Caffeine Withdrawal guide.

Which TrackCaffeine tools and pages help me manage oolong tea caffeine?

Use the caffeine half-life calculator to estimate mg remaining from a last cup, the Last Cup Before Bed planner to find a safe cutoff before sleep, and the Safe Daily Limit tool to compare your total intake to guideline levels.

Cumulative tracking is recording each source and dose of caffeine so you can total daily intake and compare against safety guidance.

You can also consult the side-by-side caffeine comparison for swap decisions (for example, how many oolongs equal one drip coffee) and the Tea Caffeine Guide for patterns across tea types; if you are pregnant, the Caffeine and Pregnancy resources explain recommended maximums and practical substitutions.

Bottom line

A standard 240 ml cup of oolong tea contains 37 mg of caffeine (per USDA FoodData Central); using a population-average half-life of 5.7 hours (model used here; Drake et al., J Clin Sleep Med, 2013) that single cup leaves about 17.8 mg after 6 hours and about 8.5 mg after 12 hours (calculated as 37 × 0.5^(6/5.7) ≈ 17.8 mg and 37 × 0.5^(12/5.7) ≈ 8.5 mg, Drake et al. half-life model; USDA cup value).

For daily safety, the U.S. FDA places an upper bound of 400 mg/day for most healthy adults (FDA), so a few 240 ml oolong cups (each 37 mg) fits comfortably under that ceiling — for example, 5 cups × 37 mg = 185 mg, well below 400 mg; however, combine oolong with coffee, matcha or energy drinks and re-calculate cumulative intake using the site tools.

If you care about sleep, avoid drinking oolong in the several hours before bedtime because measurable effects appear when substantial caffeine remains nearby bedtime (Drake et al., 2013); if you are monitoring pregnancy or adolescent intake, consult pregnancy-specific guidance and our pregnancy resources for the appropriate limit and substitutions.