Daily Caffeine Intake Calculator

Add up the caffeine in your coffee, tea, soda, energy drinks and chocolate, compare it with FDA, ACOG and pediatric guidance, and estimate what is left at bedtime.

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Results will appear here once you enter your values.

How the calculator adds up your caffeine

Each item uses the caffeine content per 100 grams listed in the USDA's FoodData Central database, multiplied by a standard serving weight. Brewed coffee lists 40 mg per 100 g, so an 8 fl oz (237 g) cup comes to about 95 mg. An espresso shot is about 64 mg, black tea about 47 mg, green tea about 28 mg, a 12 oz cola about 33 mg and a small energy drink about 75 mg. The full table, with USDA IDs, is shown under the calculator.

Real drinks vary a lot. The FDA notes a 12 oz coffee can hold anywhere from 113 to 247 mg and energy drinks from 41 to 246 mg, so use the "Other caffeine" box for anything with a label, such as pre-workout powders, caffeine pills or large coffee-shop sizes.

Daily guidelines by group

  • Healthy adults: up to 400 mg a day. The FDA describes this as an amount not generally linked to negative effects, roughly two to three 12 oz coffees.
  • Pregnant, trying to conceive or breastfeeding: under 200 mg a day, per the American College of Obstetricians and Gynecologists.
  • Teens 12-18: under 100 mg a day. The American Academy of Pediatrics advises that children and teens avoid caffeine; some pediatric health systems (e.g. Riley Children's Health) suggest adolescents stay under 100 mg a day. With a weight entered, the calculator uses Health Canada's 2.5 mg per kg if that is lower.
  • Children 4-11: Health Canada suggests no more than 2.5 mg per kg of body weight (45 mg a day for ages 4-6 if no weight is entered). Energy drinks are not recommended for children or teens.

The FDA also warns that toxic effects such as seizures have been seen with rapid intake of around 1,200 mg, which is why the calculator shows an urgent warning at that level.

Caffeine at bedtime

Caffeine is cleared gradually. StatPearls (NIH) gives a mean half-life of about 5 hours in adults, with a reported range from 1.5 to 9.5 hours: smoking speeds clearance, while pregnancy and hormonal contraceptives slow it. The calculator applies a 5-hour half-life and shows a 3-7 hour range, so 200 mg at 2 pm still leaves roughly 50-80 mg at 10 pm.

That is why an afternoon coffee can make it harder to fall asleep or reduce deep sleep even when you do not feel wired. If sleep or anxiety is a problem, try moving your last caffeine earlier before cutting it altogether.

The estimate treats the whole day's caffeine as taken at one time, so it overstates what remains if your drinks were spread out.

Common mistakes

Counting cups, not ounces. A large coffee-shop drink can be 16-20 oz, two or more servings here.

Forgetting hidden sources. Pre-workout supplements, some pain relievers, chocolate and caffeinated gum all add up.

Assuming decaf is zero. It is low, about 2 mg a cup, but not caffeine free.

Quitting suddenly. Dropping from a high intake to none can cause headaches, fatigue and low mood for a few days. Cutting back by about a quarter each week is usually easier.

This is an estimate, not medical advice. Heart rhythm problems, anxiety disorders and some medicines call for less caffeine; ask your clinician.

Frequently Asked Questions

Common questions about the Daily Caffeine Intake Calculator

For most healthy adults the FDA cites up to 400 mg a day. During pregnancy ACOG advises under 200 mg. The American Academy of Pediatrics advises that children and teens avoid caffeine; some pediatric health systems (e.g. Riley Children's Health) suggest adolescents stay under 100 mg a day.

Sources & References

Spilling the Beans: How Much Caffeine is Too Much?

400 mg/day for most adults, drink ranges, ~1,200 mg toxic effects
→Source: U.S. Food and Drug Administration

Moderate Caffeine Consumption During Pregnancy (Committee Opinion 462)

Under 200 mg/day in pregnancy
→Source: American College of Obstetricians and Gynecologists

Caffeine in foods

2.5 mg/kg/day for children and adolescents; 45 mg/day for ages 4-6
→Source: Health Canada

How much caffeine should a teenager have in a day?

Pediatric health system guidance that adolescents stay under 100 mg of caffeine a day (the calculator's teen threshold)
→Source: Riley Children's Health

FoodData Central (SR Legacy): FDC 171890, 171891, 174130, 171889, 173227, 171917, 174852, 173210, 170273

Caffeine mg per 100 g for each item
→Source: U.S. Department of Agriculture

Caffeine (StatPearls)

Mean half-life about 5 hours, range 1.5-9.5 hours
→Source: NCBI Bookshelf, National Library of Medicine

The Effects of Caffeine on Kids: A Parent's Guide

American Academy of Pediatrics parent guidance that children and teens avoid caffeine
→Source: HealthyChildren.org (American Academy of Pediatrics)

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