How Much Caffeine Is in Oolong Tea?

A 240 mL (8 fl oz) cup of brewed oolong tea typically contains about 30–50 mg of caffeine, depending on the leaves, how much you use, the water temperature and the steeping time. Use the caffeine detox calculator to help consider your overall intake.

This is an estimate, not a guaranteed range for every cup of oolong tea. A strong brew can contain more caffeine, while a weaker or diluted brew can contain less. The only way to know the exact amount in a particular brew is to have it measured.

How much caffeine is in different serving sizes of oolong tea?

The following estimates assume the tea has the same strength throughout: 30–50 mg of caffeine per 240 mL. Cup and fluid-ounce measurements are rounded.

Serving size	Estimated caffeine
120 mL (½ cup or 4 fl oz)	15–25 mg
240 mL (1 cup or 8 fl oz)	30–50 mg
360 mL (1½ cups or 12 fl oz)	45–75 mg
480 mL (2 cups or 16 fl oz)	60–100 mg
720 mL (3 cups or 24 fl oz)	90–150 mg

To estimate a different serving, divide its volume in milliliters by 240 mL, then multiply the result by 30 mg and by 50 mg. For example, 600 mL divided by 240 mL is 2.5, giving an estimate of 75–125 mg. The calculation scales the estimate; it does not account for a stronger or weaker brew.

In a small 2001 clinical trial, researchers brewed oolong tea from 15 g of leaves and served 1,500 mL containing 270 mg of caffeine. That works out to about 43 mg per 240 mL. It is an example of one preparation, not a measurement of all oolong tea.

What changes the caffeine in oolong tea?

Amount of leaves and water

Using more leaves for the same volume of water generally gives caffeine more opportunity to enter the brew. Adding water to a finished brew dilutes the caffeine concentration, but it does not remove the caffeine already in the pot. Your total intake depends on how much of that pot you drink.

Steeping time and water temperature

A longer steep generally extracts more caffeine from the leaves, although the increase is not necessarily proportional to the extra time. Hotter water can also affect extraction. Changing both time and temperature makes it difficult to predict the amount from the cup size alone.

Type of leaves

Caffeine varies among tea leaves, so different oolong tea products need not produce the same amount even when brewed the same way. A tea bag or a scoop of loose leaves is not a reliable caffeine measurement by itself: the quantity of leaves and the product can differ. If a package gives caffeine information for its brewed serving, use that figure as your starting point.

Repeated infusions

If you steep the same leaves more than once, each infusion can contain caffeine. The amount in a later infusion may differ from the first, so multiplying the first cup's estimate by the number of infusions can be misleading. Without a product-specific measurement, treat the total as approximate and remember to count every cup you drink.

How can you use a caffeine calculator for oolong tea?

Start with the size and number of your servings. If you do not have a product-specific figure, use the table above to estimate your oolong tea intake, then include caffeine from any other sources you consume that day. The calculator linked above can help you consider the total; its result is only as precise as the amounts you enter.

For most healthy adults, up to 400 mg of caffeine per day is generally considered acceptable, although sensitivity varies. This is a general limit, not a target. If you are pregnant, have a heart rhythm condition or take medication affected by caffeine, ask a healthcare professional what limit is appropriate for you.

If you are considering reducing your intake, read about how to detox from caffeine. Cutting back gradually may be more comfortable than stopping abruptly, which can cause withdrawal symptoms such as headache and fatigue.