How much caffeine is safe per day?

For most healthy adults, up to 400 mg (about 4 cups of brewed coffee) appears safe. Higher amounts can cause anxiety, insomnia, and digestive issues.

What is the half-life of caffeine?

Caffeine's half-life is 5-6 hours. If you consume 200mg at 2 PM, about 100mg remains in your system at 8 PM, which can significantly disrupt sleep quality.

Is 500mg of caffeine too much?

Yes, 500mg is above the recommended daily limit of 400mg. It may cause jitters, rapid heartbeat, and anxiety, though individual tolerance varies.

Can caffeine improve workout performance?

Yes. Caffeine is a proven ergogenic aid. A dose of 3-6 mg per kg of body weight, taken 30-60 minutes before exercise, can improve endurance and strength output.

Is caffeine bad for your heart?

Moderate consumption is generally safe. However, very high doses can cause palpitations or arrhythmias. If you have a heart condition, consult your doctor.

Do tea and soda count?

Yes. Black tea (45mg), Green tea (30mg), and Cola (35mg) all add to your daily total. Even decaf coffee contains small amounts (2-5mg).

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Caffeine Calculator

Manage your daily intake

The Caffeine Calculator allows you to track your daily caffeine intake from various sources like coffee, tea, and energy drinks to ensure you stay within safe limits.

Result

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Formula

Coffee: ~95mg per cup
Tea: ~47mg per cup
Energy drink: ~80mg
Safe limit: 400mg/day

Caffeine Content

Coffee (8oz)	80-100mg
Espresso	63mg
Black Tea	40-70mg
Green Tea	25-45mg
Cola	30-40mg

Ultimate Guide to Caffeine Intake

Caffeine is the world's most popular psychoactive substance. While it boosts alertness, performance, and mood, optimizing your intake is key to avoiding sleep disruption and anxiety.

How Much is Safe?

Healthy Adults: Up to 400 mg/day (approx. 4 cups of brewed coffee).
Pregnant Women: Often advised to limit to 200 mg/day.
Teens: Should limit to 100 mg/day.

The Half-Life Rule

Caffeine has a half-life of roughly 5-6 hours. This means 6 hours after consumption, 50% of the caffeine is still in your system. Ten hours later, 25% remains. To protect your sleep, aim to stop caffeine intake at least 8-10 hours before bed.

Common Source Values

☕ Coffee (8oz): 95 mg
🍵 Black Tea (8oz): 47 mg
⚡ Energy Drink (8oz): 80 mg (can range significantly)
🥤 Soda (12oz): 30-40 mg

References

Safety limits and content data are derived from:

U.S. Food and Drug Administration (FDA). "Spilling the Beans: How Much Caffeine is Too Much?".
Mayo Clinic. "Caffeine: How much is too much?".
European Food Safety Authority (EFSA). "Scientific Opinion on the safety of caffeine".

Frequently Asked Questions

Up to 400mg daily for healthy adults - about 4 cups of coffee. Pregnant women should limit to 200mg. People with anxiety or heart conditions may need less. Listen to your body.

Caffeine has a half-life of 5-6 hours. If you drink 200mg at 3pm, you still have 100mg in your system at 9pm. This is why afternoon caffeine disrupts sleep even if you fall asleep.

For most people, stop caffeine by 2pm for good sleep. If you're sensitive, stop by noon. Some fast metabolizers can drink coffee later without issues - know your own response.

Yes. Regular caffeine use leads to tolerance and mild physical dependence. Withdrawal symptoms (headache, fatigue, irritability) typically last 2-9 days if you quit. Tapering is easier than cold turkey.

Mildly, but coffee and tea still contribute to hydration. The fluid in caffeinated drinks more than offsets the small diuretic effect. You don't need extra water to compensate.

For most people, moderate caffeine (up to 400mg) doesn't increase heart disease risk. Some studies suggest it may be protective. Those with arrhythmias should consult their doctor.

Yes! Caffeine improves endurance, strength, and focus. 3-6mg per kg bodyweight taken 30-60 minutes before exercise is effective. It's one of the few legal performance enhancers.