Green Tea (8 oz) Caffeine Half-Life & Bedtime Decay
Standard steeped green tea (Sencha, Dragonwell) contains just 35mg of caffeine alongside relaxing theanine amino acids.
Interactive Stack Calculator for Green Tea (8 oz)
We've preloaded Green Tea (8 oz) (35mg) below. Adjust your planned bedtime or add other drinks to see your exact curve.
Caffeine Half-Life & Cutoff Calculator
Caffeine's half-life ranges from about 4 to 7 hours depending on how fast you metabolise it. Add what you've already drunk today to find the last time your next drink still leaves under 50 mg in your system at bedtime.
Caffeine Sensitivity
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Last safe 35 mg drink
Calculated so that under 50 mg of caffeine is still circulating at bedtime, counting today's drinks.
Today's drinks alone leave about 5 mg at bedtime.
Solid: caffeine from today's drinks.
Stop guessing your cutoff.
Here you type your drinks in. ARC does the same math from every drink you log in one tap, moves your last safe coffee the moment you log a cup, shows it as a live countdown, and tells you plainly when no cup fits any more.
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Green Tea (8 oz) Hour-by-Hour Caffeine Decay Table
Pharmacokinetic Decay (5.5h Half-Life)Exact milligrams of caffeine remaining in the bloodstream at 2-hour intervals if consumed at various times of day, based on an average human caffeine half-life of 5.5 hours. Target is less than 50mg active at 11:00 PM bedtime.
| Intake Time | +2 hrs | +4 hrs | +6 hrs | +8 hrs | +10 hrs | +12 hrs | At 11 PM Bed | Status |
|---|---|---|---|---|---|---|---|---|
| 08:00 AM | 27 mg | 21 mg | 16 mg | 13 mg | 10 mg | 8 mg | 5 mg | ✓ Sleep Safe |
| 12:00 PM (Noon) | 27 mg | 21 mg | 16 mg | 13 mg | 10 mg | 8 mg | 9 mg | ✓ Sleep Safe |
| 02:00 PM | 27 mg | 21 mg | 16 mg | 13 mg | 10 mg | 8 mg | 11 mg | ✓ Sleep Safe |
| 04:00 PM | 27 mg | 21 mg | 16 mg | 13 mg | 10 mg | 8 mg | 14 mg | ✓ Sleep Safe |
Cutoff Recommendation: Safe to consume up until 6:00 PM.
Values are calculated using the standard exponential decay model: mg_remaining = initial_mg * 0.5^(hours / half_life).
How Your Genetics (CYP1A2) Impact Green Tea (8 oz) Clearance
Over 95% of caffeine metabolism takes place in your liver via the cytochrome P450 enzyme CYP1A2. Depending on whether you carry the fast or slow metabolizing gene variant, clearance times for 35mg vary drastically:
Residual after 8 hours: 9 mg. You clear caffeine rapidly and rarely experience insomnia from lunch beverages.
Residual after 8 hours: 13 mg. Standard biological decay rate representing ~50% of the population.
Residual after 8 hours: 16 mg. CYP1A2*1F carriers. Any caffeine consumed past noon will disrupt sleep architecture.
Frequently asked questions
Can I drink green tea in the evening?
Yes, for average metabolisers an 8oz green tea at 6:00 PM will leave less than 18mg circulating by 11:00 PM.