Calculator
How much caffeine is in my drink?
Pick a drink and guess first. Then see the real number beside an 8 oz coffee, with where it comes from and what one at 3pm leaves at bedtime.
How much caffeine do you think is in a 16 oz coffee?
100 mg
?Brewed coffee, 16 oz
95 mgBrewed coffee, 8 ozHigher or lower
Which has more caffeine?
What your result means
- Under about 100 mg: an 8 oz coffee or less. This is the size that fits after lunch.
- About 150 to 250 mg: a 16 oz coffee, a strong can or a double shot and more. Have these in the morning, since half of one is still in you 5 hours later.
- A pre-workout scoop or a coffee-shop cup: scoops average 254 mg, and shop cups have run from 58 to 259 mg, so the label or the shop's own number is the only way to know. Treat it as your big drink of the day.
- Your guess was off: the size fools people both ways. An 8.4 oz Red Bull has less caffeine than an 8 oz coffee, and a 16 oz coffee has more than a 16 oz Monster. Go by the size of the cup first and the brand second (do energy drinks have more caffeine?).
What to do next
- Put your drink and its time into the cutoff clock to see what it leaves at your bedtime.
- Add up the whole day with the daily caffeine calculator, against the line for adults, pregnancy or teens.
Caffeine by drink
Every number with its source, checked on November 14, 2026. The last column is what one of them at 3pm still leaves at an 11pm bedtime, on a 5 hour half-life.
| Drink | Size | Caffeine | Left at 11pm from 3pm | Where it comes from |
|---|---|---|---|---|
| Brewed coffee | 8 oz | 95 mg | 35 mg | USDA FoodData Central 171890: 40 mg per 100 g, and an 8 oz cup is 237 g |
| Brewed coffee | 12 oz | 142 mg | 52 mg | USDA FoodData Central 171890 at 40 mg per 100 g, for 12 oz |
| Brewed coffee | 16 oz | 190 mg | 70 mg | USDA FoodData Central 171890 at 40 mg per 100 g, for 16 oz |
| Brewed coffee | 20 oz | 237 mg | 87 mg | USDA FoodData Central 171890 at 40 mg per 100 g, for 20 oz |
| Coffee-shop coffee | 16 oz | 58 to 259 mg | 69 mg | McCusker 2003: brewed 16 oz cups averaged 188 mg. Shop coffees ran 58 to 259 mg a serving, and one drink measured 259 to 564 mg on six days |
| Espresso | 1 shot | 63 mg | 23 mg | USDA FoodData Central 171891: 212 mg per 100 g, and a 1 oz shot is 29.6 g |
| Espresso | double | 126 mg | 46 mg | Two shots at USDA FoodData Central 171891 |
| Decaf coffee | 8 oz | 2 to 15 mg | 5 mg | FDA: typically 2 to 15 mg in an 8 oz cup. We count the top |
| Decaf espresso | 1 shot | 3 to 16 mg | 6 mg | McCusker 2006: one chain's decaf espresso measured 3.0 to 15.8 mg a shot. We count the top |
| Black tea | 8 oz | 47 mg | 17 mg | USDA FoodData Central 173227: 20 mg per 100 g |
| Green tea | 1 cup | 29 mg | 11 mg | USDA FoodData Central 171917: 12 mg per 100 g, and a cup is 245 g |
| Matcha | 2 g of powder | 32 to 84 mg | 21 mg | Two lab assays found 16.1 and 41.8 mg per gram, so about 30 to 85 mg in 2 g. We count the middle |
| Coca-Cola | 12 oz can | 34 mg | 12 mg | The Coca-Cola Company: 34 mg in a 12 oz can |
| Diet Coke | 12 oz can | 46 mg | 17 mg | The Coca-Cola Company: 46 mg in a 12 oz can |
| Red Bull | 8.4 oz can | 80 mg | 29 mg | Red Bull: 80 mg in the 8.4 oz can |
| Red Bull | 12 oz can | 114 mg | 42 mg | Red Bull: 114 mg in the 12 oz can |
| Red Bull | 16 oz can | 151 mg | 55 mg | Red Bull: 151 mg in the 16 oz can |
| Red Bull | 20 oz can | 198 mg | 72 mg | Red Bull: 198 mg in the 20 oz can |
| Monster | 16 oz can | 160 mg | 59 mg | Can label, 160 mg from all sources. Check a current can |
| CELSIUS | 12 oz can | 200 mg | 73 mg | Can label, 200 mg. Some lines differ, so check a current can |
| Energy drink | 16 oz can | 54 to 328 mg | 59 mg | FDA: 54 to 328 mg per 16 oz across brands. We count 160, a Monster |
| Pre-workout | 1 scoop | 254 mg | 93 mg | Jagim 2019: the top 100 products averaged 254 mg a serving. Check your label |
Why your cup may differ
Lab numbers are averages. Coffee-shop coffee ran from 58 to 259 mg a serving across shops, and the same drink from the same shop measured 259 to 564 mg on six days in a row. Energy drinks run from 54 to 328 mg per 16 oz across brands, so check the can. Monster and CELSIUS are from current can labels and some lines differ.
The FDA puts 400 mg a day, about two to three 12 oz cups of coffee, as an amount not generally linked to negative effects in healthy adults. See how much is too much for your group.
11 sources
- US Food and Drug Administration, Spilling the Beans: How Much Caffeine Is Too Much? Content current as of August 28, 2024fda.gov
- USDA FoodData Central, SR Legacy: brewed coffee (171890), espresso (171891), brewed black tea (173227) and brewed green tea (171917)fdc.nal.usda.gov
- McCusker RR, Goldberger BA, Cone EJ, Caffeine content of specialty coffees, Journal of Analytical Toxicology, 2003pubmed.ncbi.nlm.nih.gov
- McCusker RR and others, Caffeine content of decaffeinated coffee, Journal of Analytical Toxicology, 2006pubmed.ncbi.nlm.nih.gov
- Red Bull, How much caffeine is in a can of Red Bull?redbull.com
- The Coca-Cola Company, What is caffeine?coca-colacompany.com
- Monster Energy original, 16 fl oz, retail label listing (caffeine from all sources 160 mg)shaws.com
- CELSIUS Sparkling Kiwi Guava, 12 fl oz, retail label listing (caffeine 200 mg)shop.lowesfoods.com
- Jagim AR, Harty PS, Camic CL, Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements, Nutrients, 2019doi.org
- Koláčková T and others, Antioxidants, 2022 (16.1 mg of caffeine per gram of matcha)doi.org
- Mashaqbeh ET and others, PLOS ONE, 2026 (41.8 mg of caffeine per gram of matcha)doi.org
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With Gyroscope One, you see the milligrams and the time of your last cup, found in your drinks, next to your sleep. Open Gyroscope
