This caffeine calculator adds up the caffeine in your coffee, tea, soda, energy drinks and chocolate, compares the total with the FDA’s 400 mg daily guide (or 200 mg in pregnancy), and estimates how much is still in your body at bedtime.
| Drink or food | Caffeine (mg) each | How many |
|---|---|---|
How much caffeine is too much?
- Healthy adults: up to 400 mg a day is not generally linked with harmful effects, according to the FDA.
- Pregnancy: the American College of Obstetricians and Gynecologists advises less than 200 mg a day.
- Children and teens: energy drinks are not recommended.
Caffeine in common drinks (per 12 fl oz, FDA)
| Drink | Caffeine |
|---|---|
| Brewed coffee | 113–247 mg |
| Black tea | About 71 mg |
| Green tea | About 37 mg |
| Caffeinated soft drinks | 23–83 mg |
| Energy drinks | 41–246 mg |
Amounts vary a lot by brand and brewing, so check labels where you can.
Caffeine and sleep
Caffeine has an average half-life of about 5 hours, so half of it is still in your body 5 hours later. A coffee at 3 PM can still affect sleep at 11 PM. The calculator shows how much remains at bedtime and the latest time for an afternoon coffee.
Frequently asked questions
How much caffeine is in a cup of coffee?
An 8 oz cup of brewed coffee typically has about 80 to 100 mg, but strong or large coffee-shop drinks can have much more.
How long does caffeine stay in your system?
The average half-life is about 5 hours, ranging from roughly 2 to 10 hours depending on genetics, pregnancy, smoking and some medicines.
What are signs of too much caffeine?
Jitters, a fast heartbeat, anxiety, upset stomach, headaches and trouble sleeping.
How do I cut down on caffeine?
Reduce gradually over a week or two, swap some drinks for decaf or herbal tea, and avoid caffeine in the afternoon to protect your sleep.
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Sources
Last reviewed: October 2026. For information only; not medical advice. Talk to a doctor about any health concerns.