Celsius Heat Caffeine Half-Life & Bedtime Decay
Celsius Heat is a high-stimulant performance energy drink with 300mg of caffeine and 2,000mg of L-citrulline. At 300mg, it takes nearly 15 hours to clear from the bloodstream.
Interactive Stack Calculator for Celsius Heat
We've preloaded Celsius Heat (300mg) 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
Not sure? If an afternoon coffee keeps you up at night, pick Slow.
Pick your next drink
Last safe 300 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 45 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.
Download on theApp StoreEmbed this calculator on your site
Are you a blogger or health coach? Copy the code below to add this tool to your website and help your readers protect their sleep.
<iframe src="https://arcapp.sbs/tools/caffeine-calculator" width="100%" height="600px" frameborder="0"></iframe> <p>Caffeine calculator by <a href="https://arcapp.sbs/tools/caffeine-calculator">ARC</a></p>
Celsius Heat 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 | 233 mg | 181 mg | 141 mg | 109 mg | 85 mg | 66 mg | 45 mg | ✓ Sleep Safe |
| 12:00 PM (Noon) | 233 mg | 181 mg | 141 mg | 109 mg | 85 mg | 66 mg | 75 mg | ✕ Above 50mg |
| 02:00 PM | 233 mg | 181 mg | 141 mg | 109 mg | 85 mg | 66 mg | 96 mg | ✕ Above 50mg |
| 04:00 PM | 233 mg | 181 mg | 141 mg | 109 mg | 85 mg | 66 mg | 124 mg | ✕ Above 50mg |
Cutoff Recommendation: Strict cutoff before 11:00 AM. Any Celsius Heat consumed after noon will ruin sleep architecture.
Values are calculated using the standard exponential decay model: mg_remaining = initial_mg * 0.5^(hours / half_life).
How Your Genetics (CYP1A2) Impact Celsius Heat 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 300mg vary drastically:
Residual after 8 hours: 75 mg. You clear caffeine rapidly and rarely experience insomnia from lunch beverages.
Residual after 8 hours: 109 mg. Standard biological decay rate representing ~50% of the population.
Residual after 8 hours: 136 mg. CYP1A2*1F carriers. Any caffeine consumed past noon will disrupt sleep architecture.
Frequently asked questions
How long does Celsius Heat stay in your system?
At 300mg, you still have 150mg circulating after 5.5 hours, 75mg after 11 hours, and 37mg after 16.5 hours. It takes over 14 hours to reach the 50mg sleep threshold.