Coca-Cola (12 oz Can) Caffeine Half-Life & Bedtime Decay
A standard 12oz can of regular Coke contains 34mg of caffeine. The main sleep-disrupting factor is often the 39g of high fructose corn syrup rather than the caffeine.
Interactive Stack Calculator for Coca-Cola (12 oz Can)
We've preloaded Coca-Cola (12 oz Can) (34mg) 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.
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Last safe 34 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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Coca-Cola (12 oz Can) 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 | 26 mg | 21 mg | 16 mg | 12 mg | 10 mg | 7 mg | 5 mg | ✓ Sleep Safe |
| 12:00 PM (Noon) | 26 mg | 21 mg | 16 mg | 12 mg | 10 mg | 7 mg | 9 mg | ✓ Sleep Safe |
| 02:00 PM | 26 mg | 21 mg | 16 mg | 12 mg | 10 mg | 7 mg | 11 mg | ✓ Sleep Safe |
| 04:00 PM | 26 mg | 21 mg | 16 mg | 12 mg | 10 mg | 7 mg | 14 mg | ✓ Sleep Safe |
Cutoff Recommendation: Safe until 6:00 PM in terms of caffeine decay.
Values are calculated using the standard exponential decay model: mg_remaining = initial_mg * 0.5^(hours / half_life).
How Your Genetics (CYP1A2) Impact Coca-Cola (12 oz Can) 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 34mg vary drastically:
Residual after 8 hours: 9 mg. You clear caffeine rapidly and rarely experience insomnia from lunch beverages.
Residual after 8 hours: 12 mg. Standard biological decay rate representing ~50% of the population.
Residual after 8 hours: 15 mg. CYP1A2*1F carriers. Any caffeine consumed past noon will disrupt sleep architecture.
Frequently asked questions
How much caffeine is in a can of Coke compared to coffee?
A can of Coke (34mg) has about one-third the caffeine of an 8oz home coffee (95mg) and one-ninth of a Starbucks Grande drip (310mg).