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Caffeine Calculator

Track your daily caffeine intake. Add each cup and see where you stand against the FDA's 400 mg limit.

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FDA daily limit: 400 mg

Half-life: ~5 hours

Caffeine's half-life averages 5 hours but ranges 1.5–10 hours depending on genetics. A 3pm coffee means ~half is still active at 8pm.

Pregnancy: 200 mg max

ACOG recommends no more than 200 mg/day during pregnancy. Caffeine crosses the placenta and its half-life extends up to 3x in the third trimester. Decaf options →

Fast vs slow metabolizers

The CYP1A2 gene determines how fast you process caffeine — clearance varies up to 40-fold between people. If coffee keeps you up at night, you may be a slow metabolizer.

Espresso myth

Espresso has MORE caffeine per ml, but LESS per serving. A single shot (~63 mg) has far less caffeine than an 8 oz drip (~95 mg). The "espresso = more caffeine" perception comes from its extreme concentration, not its total content. Espresso shots explained →

Stomach sensitivity?

Caffeine itself triggers gastric acid production — independent of the coffee's acidity. Paper-filtered methods, cold brew, and lower doses can all help. Low acid coffee guide →

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