Safe for sleep (<50mg) May affect sleep (50-100mg) Likely affects sleep (>100mg)
Detailed Caffeine Levels
Caffeine Tips
Most experts recommend limiting caffeine to 400mg per day for healthy adults.
Avoid caffeine at least 6 hours before bedtime for better sleep quality.
Caffeine sensitivity varies by genetics, age, and regular consumption habits.
Pregnant women should limit caffeine to 200mg per day.
Regular caffeine users may develop tolerance, requiring more for the same effect.
Common Caffeine Content
Brewed Coffee (8 oz)95mg
Espresso (1 shot)63mg
Black Tea (8 oz)47mg
Green Tea (8 oz)28mg
Cola (12 oz)34mg
Red Bull (8.4 oz)80mg
Monster (16 oz)160mg
Dark Chocolate (1 oz)12mg
Disclaimer: This calculator provides estimates based on average caffeine half-life data. Individual metabolism varies significantly based on genetics, liver function, medications, pregnancy, and other factors. Consult a healthcare provider for personalized advice.
Add this Calculator to Your Site
Understanding Caffeine Half-Life
Caffeine is the world's most widely consumed psychoactive substance. Understanding how your body processes caffeine can help you optimize your energy levels while protecting your sleep quality.
What is Caffeine Half-Life?
Half-life refers to the time it takes for the amount of caffeine in your bloodstream to reduce by half. For most healthy adults, caffeine's half-life is approximately 5-6 hours, but this can range from 1.5 to 9.5 hours depending on individual factors.
Factors Affecting Caffeine Metabolism
Genetics: The CYP1A2 gene determines how quickly your liver processes caffeine. Some people are "fast metabolizers" while others are "slow metabolizers."
Age: Older adults tend to metabolize caffeine more slowly.
Pregnancy: Caffeine half-life can double or triple during pregnancy.
Liver Health: Liver conditions can significantly slow caffeine metabolism.
Smoking: Smokers metabolize caffeine about 50% faster than non-smokers.
Medications: Some medications, especially oral contraceptives, can slow caffeine metabolism.
Caffeine and Sleep
Even if you don't feel the stimulant effects of caffeine, it can still affect your sleep quality. Research suggests that caffeine consumed up to 6 hours before bedtime can reduce total sleep time and sleep efficiency. For optimal sleep, many experts recommend avoiding caffeine after 2 PM.
Safe Caffeine Intake
The FDA recommends a maximum of 400mg of caffeine per day for healthy adults - roughly equivalent to four 8-ounce cups of brewed coffee. However, individual tolerance varies, and some people may experience negative effects at lower doses.
