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Caffeine Half‑Life Tracker - Online Blood Level Visualizer

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Metabolism Settings
5.0h
Fast (2h)TypicalSlow (8h)
Healthy adults: 4–5h. Smokers: ~3h. Pregnant: 10–15h.
Add Caffeine Intake
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hrs
Bedtime Check
Set bedtime to estimate residual caffeine.
Blood Caffeine Level Visualization
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Total: —
Half-life at: —
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At Bedtime: —
Frequently Asked Questions About Caffeine Metabolism
What is caffeine half-life?

Caffeine half-life is the time it takes for your body to eliminate half of the caffeine in your bloodstream. For most healthy adults, this ranges from 4 to 5 hours. This means if you consume 200mg of caffeine, about 100mg remains after one half-life, 50mg after two half-lives, and so on.

How long does caffeine stay in your system?

Caffeine is typically fully cleared from your body within 5 half-lives (around 20–25 hours for most people), when less than 3% of the original dose remains. However, traces can be detectable for up to 48 hours depending on individual metabolism, liver function, and genetic factors.

What factors affect caffeine half-life?

Several factors influence how quickly you metabolize caffeine: genetics (CYP1A2 enzyme variants), pregnancy (half-life can extend to 10–15 hours), smoking (speeds up metabolism to ~3 hours), liver health, age, and medications like oral contraceptives which can double the half-life.

How much caffeine is safe before bedtime?

Sleep experts recommend keeping bedtime caffeine levels below 50mg for quality sleep. Since caffeine blocks adenosine receptors, even moderate amounts can disrupt deep sleep stages. It's generally advised to avoid caffeine 6–8 hours before sleep. Use this tracker to estimate your bedtime caffeine residual.

What are typical caffeine amounts in drinks?

Common caffeine contents: Drip coffee (8oz): ~95mg, Espresso (1 shot): ~63mg, Black tea (8oz): ~47mg, Green tea (8oz): ~28mg, Cola (12oz): ~34mg, Energy drink (8oz): ~80mg, Dark chocolate (1oz): ~12mg. The FDA recommends no more than 400mg per day for healthy adults.

How accurate is this tracker?

This tracker uses standard first-order pharmacokinetics with an exponential decay model: C(t) = C₀ × e^(-ln(2)×t/halfLife). While individual metabolism varies, this model provides a reliable estimate. For personalized medical advice, consult your healthcare provider. The tool accounts for multiple intakes by summing their individual decay curves.

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