Dunkin' Iced Coffee (Medium) Caffeine Half-Life & Bedtime Decay
Dunkin's Medium Iced Coffee packs an astounding 297mg of caffeine in 24 fl oz—nearly triple a standard cup of coffee and higher than almost all commercial energy drinks.
Interactive Stack Calculator for Dunkin' Iced Coffee (Medium)
We've preloaded Dunkin' Iced Coffee (Medium) (297mg) 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 297 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.
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Dunkin' Iced Coffee (Medium) 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 | 231 mg | 179 mg | 139 mg | 108 mg | 84 mg | 65 mg | 45 mg | ✓ Sleep Safe |
| 12:00 PM (Noon) | 231 mg | 179 mg | 139 mg | 108 mg | 84 mg | 65 mg | 74 mg | ✕ Above 50mg |
| 02:00 PM | 231 mg | 179 mg | 139 mg | 108 mg | 84 mg | 65 mg | 96 mg | ✕ Above 50mg |
| 04:00 PM | 231 mg | 179 mg | 139 mg | 108 mg | 84 mg | 65 mg | 123 mg | ✕ Above 50mg |
Cutoff Recommendation: Never drink Dunkin' Medium Iced Coffee past 12:00 PM noon if you want restorative deep sleep tonight.
Values are calculated using the standard exponential decay model: mg_remaining = initial_mg * 0.5^(hours / half_life).
How Your Genetics (CYP1A2) Impact Dunkin' Iced Coffee (Medium) 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 297mg vary drastically:
Residual after 8 hours: 74 mg. You clear caffeine rapidly and rarely experience insomnia from lunch beverages.
Residual after 8 hours: 108 mg. Standard biological decay rate representing ~50% of the population.
Residual after 8 hours: 134 mg. CYP1A2*1F carriers. Any caffeine consumed past noon will disrupt sleep architecture.
Frequently asked questions
Why is Dunkin' Iced Coffee so high in caffeine?
Dunkin' double-brews their iced coffee hot using twice the amount of coffee grounds so that melting ice does not dilute the flavor, resulting in 297mg of dissolved caffeine per medium cup.
How long does 297mg of Dunkin' caffeine take to clear?
It takes nearly 14 hours for 297mg to decay down to 50mg in an average metaboliser. If consumed at 1:00 PM, you will still have over 80mg circulating at midnight.