Caffeine Cut-Off Calculator
Your personal last-coffee time from bedtime and metabolism speed — half-life math applied to sleep.
The target is ≤50 mg circulating at lights-out — roughly half a cup's worth, below most people's sleep-disruption threshold. Genetics (CYP1A2) spread half-lives from 2 to 10 hours, which is why your colleague's post-dinner espresso is fine and yours isn't. Drazen's controlled trial found caffeine even 6 h pre-bed cut measured sleep by an hour while subjects didn't notice.
Formula
For general information only — not medical advice, a diagnosis or a treatment plan. Consult a qualified healthcare professional before making health, diet, medication or exercise decisions.
Your personal last-coffee time from bedtime and metabolism speed — half-life math applied to sleep. The Caffeine Cut-Off Calculator is a free, private caffeine cutoff tool — every result computes instantly in your browser with no sign-up and no data upload.
About Caffeine Cut-Off Calculator
The target is ≤50 mg circulating at lights-out — roughly half a cup's worth, below most people's sleep-disruption threshold. It applies cut-off = bedtime − t½ × log₂(dose ÷ 50 mg residual target). Use the Caffeine Cut-Off Calculator to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Caffeine Cut-Off Calculator
- 1Enter your details in the Caffeine Cut-Off Calculator input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Caffeine Cut-Off Calculator?
- ✓Instant caffeine cutoff result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Drake C et al., J Clin Sleep Med 2013 — caffeine effects 0, 3, 6 h before bed)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Caffeine Cut-Off Calculator work?+
The target is ≤50 mg circulating at lights-out — roughly half a cup's worth, below most people's sleep-disruption threshold. The calculation uses the formula: cut-off = bedtime − t½ × log₂(dose ÷ 50 mg residual target). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Caffeine Cut-Off Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources: Drake C et al., J Clin Sleep Med 2013 — caffeine effects 0, 3, 6 h before bed. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Caffeine Cut-Off Calculator free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is for general information only and is not medical advice. Always consult a qualified healthcare professional before making health decisions.
What can I use the Caffeine Cut-Off Calculator for?+
It's commonly used for caffeine cutoff, last coffee time, caffeine before bed. Your personal last-coffee time from bedtime and metabolism speed — half-life math applied to sleep.
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