Rockstarに含まれるカフェイン量はどれくらい？

A 473 ml (16 fl oz) can of Rockstar Energy Drink contains 160 milligrams of caffeine. This equals 33.8 mg of caffeine per 100 ml, placing it in the mid-range of the energy drink category and equivalent to about 1.7 cups of standard drip coffee, which provides 96 mg per 240 ml serving. For someone accustomed to a morning coffee, a single Rockstar delivers a noticeable but not extreme stimulant effect, typically beginning within 15 to 45 minutes of the first sip.

What that 160 mg figure means in practice is a period of heightened alertness driven by adenosine receptor blockade, which temporarily suppresses the brain's sleep signal. At this dose, most healthy adults experience improved reaction time and sustained attention without the more pronounced jitteriness or peripheral tremor that can accompany 300 mg energy drinks like Bang or Reign. Because Rockstar uses a standard 473 ml can, the entire dose is usually consumed in one sitting, making the intake predictable—unlike a hand-poured coffee where bean origin, grind size, and brew method can swing the caffeine content by 80 mg or more in the same cup size.

Rockstarが体内にどれくらい残るか

Caffeine follows first-order elimination kinetics, meaning the body removes a constant fraction of the remaining drug per unit time. For a population-average half-life of 5.7 hours, the amount left in the bloodstream from a 160 mg Rockstar is calculated as remaining = 160 × 0.5^(hours / 5.7). At 3 hours post-consumption, roughly 111 mg remains; at 6 hours, 77 mg; at 9 hours, 54 mg; and by 12 hours, 37 mg. These numbers are not trivial—37 mg is more than the entire caffeine content of a 355 ml can of Coca-Cola Coke Zero (34 mg), and it is still pharmacologically active enough to occupy adenosine receptors in the central nervous system.

If a person finishes a 160 mg Rockstar at 15:00, the 77 mg still circulating at 21:00 is equivalent to swallowing about 80% of another Red Bull 250 ml can right before settling into the evening routine. That lingering dose can delay sleep onset by 40 minutes or more, according to a 2013 study by Drake et al. in the Journal of Clinical Sleep Medicine, which found that 400 mg of caffeine consumed six hours before bed still reduced total sleep time by over one hour. The arithmetic on the half-life curve explains why the 21:00 residual from a mid-afternoon Rockstar is a direct sleep-stealer, even when the subjective “rush” faded long before.

A 160 mg Rockstar consumes 40% of the widely-cited 400 mg daily limit for healthy adults identified by both the U.S. Food and Drug Administration and the European Food Safety Authority in its 2015 risk assessment. That means 2.5 cans exactly reach the ceiling, and three cans at 480 mg would overshoot it by 80 mg—equivalent to drinking an extra 250 ml Red Bull beyond the safety threshold. This is a tight margin that disappears quickly if any other caffeine source enters the day: a morning drip coffee (96 mg) plus a single Rockstar (160 mg) already sits at 256 mg, leaving only 144 mg of headroom, which is less than a second Rockstar and barely enough space for a 355 ml Coke Zero (34 mg) and a square of dark chocolate without breaching 400 mg.

Sleep protection requires planning backward from the half-life. With a 23:00 bedtime and a 5.7-hour half-life, the last 160 mg Rockstar should ideally be finished by roughly 11:30 to 12:00 to leave a circulating dose under 50 mg—the toxicity threshold at which Drake et al. (2013) observed significant sleep disruption merely from 400 mg consumed six hours prior. For a single can, finishing at 15:00 leaves about 77 mg at 21:00, which is a dose large enough to reduce slow-wave sleep in sensitive individuals. Populations with longer caffeine half-lives—pregnant individuals (EFSA suggests a 200 mg/day limit during pregnancy), adolescents whose hepatic CYP1A2 enzyme system is still maturing, and slow metabolizers with genetic polymorphisms—should compress the consumption window further or substitute a lower-dose alternative like the 80 mg Red Bull. The latest cup before bedtime calculator automates these timing calculations for any dose and target bedtime, including the specific 160 mg input from Rockstar.

At 160 mg per 473 ml can, Rockstar occupies the exact center of the mainstream energy drink category as defined by its closest competitors. It aligns dose-for-dose with NOS (160 mg) and Monster Energy (160 mg), making the three effectively interchangeable in a caffeine-per-can sense. Stacked against the lighter category entries, a single Rockstar delivers double the 80 mg found in the standard 250 ml Red Bull can, and 46 mg more than the 114 mg present in the larger 355 ml Red Bull. Between the ultra-extreme tier—Bang (300 mg) and Reign (300 mg)—a single Rockstar is nearly half the stimulant load, which matters when a second can is considered: two Rockstars supply 320 mg, eclipsing one Bang by 20 mg.

When measured against coffee, the comparison sharpens. A 473 ml can of Rockstar provides the caffeine equivalent of consuming a single 240 ml cup of drip coffee (96 mg) plus a tall brewed coffee of 180 ml (72 mg) in sequence, without the 20-minute ingestion lag of sipping hot liquid. That rapid intake profile explains why the energy drink “lift” can feel subjectively sharper, even though the absolute milligram number is not exceptionally high. Placed next to rising competitors like Celsius (200 mg) and Prime Energy (200 mg), Rockstar is clearly the more moderate choice, delivering 40 mg less per can and therefore fitting more easily inside the FDA’s 400 mg daily guidance without forcing deliberate half-can portioning.

In terms of caffeine density, Rockstar’s 33.8 mg per 100 ml is significantly lower than a single espresso shot at 63 mg in 30 ml (210 mg per 100 ml), but the large volume of the energy drink means the absolute dose is 2.5 times greater than that one shot. The volumetric comparison matters because consumers who think in “cups” rather than “cans” can mistake volume for potency: a Rockstar can looks and pours like a medium coffee, but it carries 67% more caffeine than the reference 240 ml drip cup—a fact that is only apparent when the two are normalized by their caffeine-per-volume metric, which our side-by-side drink comparison tool does automatically.

Rockstarの数値を左右する要素

Rockstar is not a single product but a brand portfolio spanning at least two dozen formulations, and the 160 mg figure in this page applies specifically to the original 473 ml can sold in most markets. Even within that single SKU, natural variability exists because caffeine is added as a controlled ingredient during manufacturing, and blending tolerances can shift the per-can content by an estimated ±5%, placing real-world cans somewhere between about 152 mg and 168 mg. The brand itself does not publish batch-level certificates of analysis, so the label claim is the best available point estimate rather than a measured constant.

Other variants in the Rockstar line move the needle significantly. Rockstar Pure Zero, a zero-sugar line, offers a 240 mg caffeine dose in the same 473 ml volume, while Rockstar XD Power pushes to 300 mg per can, matching the extreme end of the category occupied by Bang and Reign. Conversely, Rockstar Recovery, marketed for post-exercise rehydration, contains only 160 mg across a 473 ml can and often includes electrolytes alongside the same base stimulant load. Rockstar also produces a 355 ml (12 fl oz) size in some regions, with a proportionally lower caffeine content around 120 mg, though the company does not always label the smaller can with a unique nutritional panel.

An important absence is any decaffeinated or caffeine-free version of Rockstar. Unlike major coffee chains that routinely offer decaf espresso (where a single shot retains roughly 3–15 mg of caffeine per EFSA guidance), the Rockstar portfolio is entirely stimulant-containing. This means anyone seeking the flavor or ritual of an energy drink without the pharmacological effect must look to brands outside the Rockstar family, such as caffeine-free Zevia Energy or specific niche formulations documented in our caffeine-free energy drinks guide. Consumers who rely on taste or brand routine alone can inadvertently consume a full 160 mg dose when they intended zero, a mistake that is impossible to make with coffee when the word “decaf” is clearly stated on the cup.

Regional variation adds another layer. In Canada, health regulations cap caffeine at 180 mg per single-serve container for energy drinks; Rockstar complies with the 160 mg label claim across both U.S. and Canadian recipes, but European formulations occasionally use slightly different amounts of added caffeine relative to the base liquid volume. Always check the local nutrition facts panel, because the 33.8 mg per 100 ml benchmark is the most portable number: multiply the millilitres you actually drink by 0.338 and you have your intake regardless of whether the can says 16 fl oz or 500 ml.

この数値の出典

The 160 mg figure on this page comes directly from the official Rockstar Energy product label as filed with the USDA FoodData Central database, which aggregates manufacturer-reported nutrition facts panels. This number is the company’s stated “added caffeine” combined with any naturally occurring caffeine from ingredients such as guarana seed extract, which Rockstar lists on its ingredient panel and which contributes an estimated 4–10 mg per can based on typical guarana caffeine concentrations documented by the EFSA. Where disagreement arises—some third-party laboratory tests report values between 156 mg and 164 mg for the same product—the difference is attributed to batch variation, regional recipe tweaks, and the sensitivity of high-performance liquid chromatography methods used to quantify xanthines.

We would update this page if any of three evidence streams shifted: a new official label change from Rockstar’s parent company (PepsiCo), repeated independent lab analyses that deviated from the labeled claim by more than 10% over multiple batches, or a regulatory enforcement action from the FDA that compelled a reformulation. Our dataset source file, indexed in the open caffeine dataset, includes the original USDA food code and the date of our last label verification, so any user can trace the provenance and see exactly when and how the number was obtained. Published caffeine databases like the Mayo Clinic caffeine chart often round or use branded products that change over time; this page commits to a specific serving size, a specific variant, and a timestamped source, which is the only durable response to the reality that “Rockstar caffeine content” is a moving target.

結論

A 473 ml can of Rockstar Energy Drink contains 160 mg of caffeine. That is 33.8 mg per 100 ml, the same dose as a can of Monster Energy and NOS, 40% of the FDA’s 400 mg daily limit, and roughly equivalent to 1.7 cups of drip coffee. With a 5.7-hour half-life, 77 mg remains in the bloodstream six hours after consumption—enough to interfere with sleep if taken in the afternoon. Anyone counting on a precise intake should read the label on the can in hand, because Rockstar’s portfolio spans from 160 mg to 300 mg depending on the variant, and the number on this page applies only to the original formulation.