Caffeine Calculator

How much of your favorite teas or other caffeinated drinks are safe to consume?

This caffeine calculator helps you understand the caffeine content of your favorite drinks and how much caffeine you’ve had in total throughout the day. Then, you’ll be able to decide if you should slow down, or go ahead and have one more cup! Use this tool anyway you like—as a reference or a caffeine intake calculator.

Below you will find information like how much caffeine is too much and how much caffeine is appropriate per day. The generally accepted safe upper limit of caffeine (for adults) per day is 400 milligrams of caffeine. So let’s see how much caffeine your favorite drinks have!

Tea Caffeine Calculator: Includes loose leaf teas like oolong tea, green tea, and black tea, caffeine in Starbucks tea, and the most well-known ready-to-drink bottled iced teas. This is the quick lookup caffeine intake calculator. 

Advanced Tea Caffeine Calculator: for loose leaf tea lovers—select tea, serving size, and number of steeps. Use this if you multi-steep loose leaf tea. 

Ounce to Milliliter Serving Conversion
Ounce Size 8oz 12oz 16oz 20oz
Milliliter Size 237ml 355ml 473ml 591ml
Starbucks Size Short Tall Grande Venti


Caffeine varies with water temperature, tea type, steep time, roast, growing conditions, and extraction method.

Teas brewed at ratio of 1:50 (grams/ml) boiling water to tea leaves, steeped for 6 minutes. Cold brew, 4 hours.

How Much Is Too Much Caffeine?

Up to 400 milligrams of caffeine per day is considered an acceptable intake for healthy adults. (If you are pregnant or have specific conditions please refer to your doctor for acceptable caffeine intake.)

What Is Caffeine?

Caffeine is a central nervous system stimulant that is used to increase energy, alertness, and focus. Caffeine is most often consumed as coffee, tea, soft-drinks, and energy drinks. Caffeine is also found in chocolate, some seeds, snacks, other beverages, and foods.

Which Tea Has the Most Caffeine?

Black Tea contains the most caffeine at approximately 60-100 mg per 8 ounce cup. However caffeine levels change with oxidation, brewing method, steep time, and other factors.

How Much Caffeine Is in a Cup of Coffee?

In general brewed coffee contains 95-140 mg per 8 ounce cup while an espresso contains 47-75 mg per 30 ml cup. A Grande Starbucks brewed coffee contains 310 mg of caffeine. However, like tea, caffeine in coffee comes down brewing method, roast, type of beans, and other factors. 

How Much Caffeine Is in Decaf Beverages?

Decaffeinated drinks are not truly 100% caffeine-free. For a tea or coffee to be considered decaffeinated 97% of caffeine must be removed, therefore at least 3% caffeine will remain.

Even though there is some caffeine in decaffeinated drinks, the amount is so small it has almost no effect on a healthy adult.

How much caffeine should I have Daily?

The answer is…it depends…

The amount of caffeine you should consume daily depends on your age, health condition, and a variety of personal factors. However, a healthy adult should try not to exceed 400 mg. That is about 3-4 mugs of coffee or tea.

How Much Caffeine Is Dangerous?

The general assumption is that 10 grams of caffeine can be lethal to humans. That’s about 180 cups of tea or 75 cups of coffee. If you are consuming a bit more than the recommended daily intake of caffeine, don’t worry! It is unlikely that a couple extra cups will cause adverse reactions in normal healthy adults. But as with all things, DO monitor how you’re feeling and listen to your doctors and your body.

How to use the Caffeine Calculator

This tool will show you how much caffeine is in your favorite cup of tea, depending on type of tea, size, brewing method, and number of steeps.

There are a lot of teas to choose from, and this tool will help you figure out approximately how much caffeine you are consuming (so you don’t get too much…or too little when you need that jolt!)

  1. First, choose the type of tea.
  2. Then, chose your serving size.
  3. If you’re using the advanced calculator, choose steep number.
  4. Voila! The caffeine calculator will automatically show you the amount of caffeine in your cup.

As with all good things, enjoy your caffeine responsibly and in moderation.

For more information about what affects the amount of caffeine in your tea, check out our blog post about caffeine in Oolong teas!