How much caffeine is in coffee?

A cup (8 oz) of brewed coffee typically contains 80-100mg of caffeine. Espresso (1 oz) has 63mg. The exact amount depends on bean type, roast level, and brewing method. Darker roasts sometimes have slightly less caffeine than lighter roasts.

What are signs of too much caffeine?

Excessive caffeine consumption can cause jitteriness, anxiety, rapid heartbeat, sleep disturbances, digestive issues, and headaches. If you experience these symptoms, reduce your daily caffeine intake gradually to avoid withdrawal.

How long does caffeine stay in your system?

Caffeine has a half-life of about 5-6 hours, meaning it takes about 5-6 hours for your body to eliminate half the caffeine consumed. Full elimination can take 12-24 hours. This is why consuming caffeine late in the day can affect sleep.

Can caffeine affect sleep?

Yes, caffeine can significantly impact sleep quality and duration. It's recommended to avoid caffeine 6-8 hours before bedtime. Even small amounts can affect sensitive individuals. Consistent sleep disruption can accumulate over time.

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Caffeine Calculator

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Daily Limit: 400 mg (FDA Recommendation)

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⚠️ Medical Disclaimer: This calculator is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making health-related decisions.

About Caffeine Calculator

This caffeine calculator helps you track your daily caffeine consumption and stay within safe limits. Caffeine is one of the most widely consumed psychoactive substances worldwide, found in coffee, tea, energy drinks, and many other products.

Caffeine Content by Beverage

Brewed Coffee (8 oz): 80-100mg
Espresso (1 oz): 63mg
Black Tea (8 oz): 25-50mg
Green Tea (8 oz): 25-50mg
Energy Drink (8 oz): 80-150mg
Cola (12 oz): 34-46mg
Chocolate (1 oz): 5-10mg

Recommended Daily Limits

Healthy Adults: Up to 400mg per day
Pregnant Women: Up to 200mg per day
Adolescents (12-18): Less than 100mg per day
Children (under 12): Should avoid caffeine

Signs of Excessive Caffeine

Jitteriness and anxiety
Rapid or irregular heartbeat
Sleep disturbances and insomnia
Digestive issues and acid reflux
Frequent urination
Muscle tremors

How Long Caffeine Stays in Your System

Caffeine has a half-life of about 5-6 hours. This means half the caffeine you consume is eliminated every 5-6 hours. For example, if you drink 200mg of caffeine at noon, you'll have about 100mg in your system at 5-6 PM, and 50mg remaining by late evening. This is why consuming caffeine late in the day can interfere with sleep.