Why use this calculator
Caffeine affects sleep, anxiety, and heart health. Tracking your daily intake helps you stay within safe limits and understand why you might feel jittery or have trouble sleeping.
How to use it
Enter the number of each caffeinated beverage you consume in a day. The calculator totals your caffeine intake, compares it to the FDA maximum, and estimates how long it takes to clear your system.
The formula
Total mg = (espresso * 63) + (coffee * 95) + (tea * 47) + (soda * 34) + (energy * 80); Metabolize time = log2(total/10) * 5 hours
Worked examples
2 espresso shots + 1 drip coffee
221 mg total, 55% of daily max, ~22 hours to fully metabolize
3 cups of tea + 1 energy drink
221 mg total, 55% of daily max
When people use it
- Monitoring caffeine intake for better sleep quality
- Managing anxiety symptoms related to caffeine consumption
- Planning caffeine cutoff times for evening rest
- Tracking intake during pregnancy when limits are lower
Tips
- The FDA recommends no more than 400 mg of caffeine per day for healthy adults
- Stop caffeine intake at least 6 hours before bedtime for better sleep
- Caffeine has a half-life of about 5 hours, meaning half remains in your system after 5 hours
- Pregnant women should limit caffeine to 200 mg per day
Questions people ask
- How accurate are the caffeine amounts?
- These are average values. Actual caffeine content varies by brand, brewing method, and serving size. Espresso can range from 50-75 mg per shot.
- What does half-life mean for caffeine?
- Half-life is the time it takes for your body to eliminate half the caffeine. With a 5-hour half-life, 200 mg at noon becomes 100 mg by 5 PM and 50 mg by 10 PM.
- Is decaf coffee truly caffeine-free?
- No, decaf coffee still contains 2-15 mg of caffeine per cup. If you are very sensitive, this can still have an effect.