Caffeine Cutoff Time Calculator

Estimate the latest time you can have caffeine so your bedtime caffeine level stays below a target. Educational estimate — not medical advice.

Half-life model Sensitivity tiers Bedtime target

Based on research showing caffeine can affect sleep even 6 hours before bed

If you’re unsure, pick “High sensitivity” (slower clearance) and use a lower bedtime target.

Target bedtime

Your usual lights-out time.

Planned last dose (mg)

Typical coffee: ~80–120mg (varies).

Sensitivity (half-life)

Average half-life is often cited around ~5–6 hours, but it varies.

Target caffeine at bedtime (mg)

Lower target = earlier cutoff (more conservative).

Absorption buffer (minutes)

Conservative buffer for “kick-in” time.

Tip: if you consistently have trouble falling asleep, try an earlier cutoff (or a higher sensitivity tier) and compare over a week.

FAQ

Why does the calculator ask for a “target mg” at bedtime?

Different people tolerate different residual caffeine. A bedtime target gives you a clear “how conservative do I want to be?” control.

Is this medical advice?

No. This tool provides an educational estimate. If you have medical concerns or take medications, talk to a clinician.