French Press Coffee (12 oz) Caffeine Half-Life & Bedtime Decay
French press uses a coarse grind with a 4-minute full immersion steep in hot water. Because the stainless steel mesh allows fine coffee oils and suspended micro-grounds through, a 12oz cup delivers roughly 180mg of caffeine.
Interactive Stack Calculator for French Press Coffee (12 oz)
We've preloaded French Press Coffee (12 oz) (180mg) 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 180 mg drink
For this drink size, the safe window closed earlier today. A smaller drink, or decaf, may still fit.
Today's drinks alone leave about 27 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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French Press Coffee (12 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 | 140 mg | 109 mg | 85 mg | 66 mg | 51 mg | 40 mg | 27 mg | ✓ Sleep Safe |
| 12:00 PM (Noon) | 140 mg | 109 mg | 85 mg | 66 mg | 51 mg | 40 mg | 45 mg | ✓ Sleep Safe |
| 02:00 PM | 140 mg | 109 mg | 85 mg | 66 mg | 51 mg | 40 mg | 58 mg | ✕ Above 50mg |
| 04:00 PM | 140 mg | 109 mg | 85 mg | 66 mg | 51 mg | 40 mg | 74 mg | ✕ Above 50mg |
Cutoff Recommendation: Enjoy your last French press coffee before 1:45 PM for an 11:00 PM bedtime.
Values are calculated using the standard exponential decay model: mg_remaining = initial_mg * 0.5^(hours / half_life).
How Your Genetics (CYP1A2) Impact French Press Coffee (12 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 180mg vary drastically:
Residual after 8 hours: 45 mg. You clear caffeine rapidly and rarely experience insomnia from lunch beverages.
Residual after 8 hours: 66 mg. Standard biological decay rate representing ~50% of the population.
Residual after 8 hours: 82 mg. CYP1A2*1F carriers. Any caffeine consumed past noon will disrupt sleep architecture.
Frequently asked questions
Why is French press coffee so strong?
Full water-ground contact time over 4 to 5 minutes extracts a higher percentage of total dissolved solids and caffeine compared to fast paper-filtered pour-over methods.