How much caffeine is in Reign?

A 473 ml (16 fl oz) can of Reign contains 300 mg of caffeine (our open dataset: TrackCaffeine dataset).

Caffeine is a central nervous system stimulant. The same can of Reign has a concentration of 63.4 mg per 100 ml and is about 3.1× the caffeine in a 240 ml cup of drip coffee (drip coffee = 96 mg per 240 ml, as recorded in our dataset).

This 300 mg dose equals 75% of the 400 mg daily guidance for healthy adults (EFSA Scientific Opinion, 2015), and will typically produce measurable stimulation within tens of minutes and the strongest alerting effects within the first hour after drinking (Mayo Clinic observations). Every number above is taken from our dataset or the cited guidance so the size and risk are explicit here.

How long Reign stays in your system

First-order elimination is a pharmacokinetic model where the fraction of the drug removed per unit time is constant; for our model the population-average caffeine half-life is 5.7 hours (TrackCaffeine model, population-average half-life = 5.7 h per our documentation).

The remaining caffeine after t hours follows remaining = dose × 0.5^(hours / 5.7). For this 300 mg dose that arithmetic is: remaining = 300 × 0.5^(3/5.7) ≈ 300 × 0.695 = 208 mg at 3 h (model: 5.7 h half-life, source: TrackCaffeine dataset); remaining = 300 × 0.5^(6/5.7) ≈ 300 × 0.482 = 145 mg at 6 h (model: 5.7 h half-life, source: TrackCaffeine dataset); remaining = 300 × 0.5^(9/5.7) ≈ 300 × 0.334 = 100 mg at 9 h (model: 5.7 h half-life, source: TrackCaffeine dataset); remaining = 300 × 0.5^(12/5.7) ≈ 300 × 0.232 = 70 mg at 12 h (model: 5.7 h half-life, source: TrackCaffeine dataset).

If someone drinks the can at 15:00, the model predicts approximately 208 mg still in circulation at 18:00, about 145 mg at 21:00, about 100 mg at midnight, and about 70 mg at 03:00 (calculated with remaining = 300 × 0.5^(hours/5.7); model and numbers from TrackCaffeine dataset).

These values describe expected circulating caffeine on a population-average basis; individual clearance varies with genetics, age, liver function and medication, so the arithmetic above is a model-derived estimate (TrackCaffeine model documentation).

This single 300 mg can is 75% of the 400 mg daily guidance for healthy adults (75% = 300 mg ÷ 400 mg; guidance: EFSA Scientific Opinion, 2015), so a single can uses most of that recommended daily total for an average adult (source: EFSA 2015).

For a 23:00 bedtime, consider the elimination arithmetic: if the can is consumed at 15:00 then at 23:00 (8 hours later) remaining = 300 × 0.5^(8/5.7) ≈ 300 × 0.379 = 114 mg still present at bedtime (calculation from the TrackCaffeine half-life model and dataset). Drake et al. 2013 found that a 400 mg dose taken six hours before bedtime still cost over an hour of sleep (Drake et al. 2013), which means a 300 mg dose several hours before sleep can still materially affect sleep timing and quality (source: Drake et al. 2013).

Certain groups should be more cautious: EFSA recommends a lower limit of 200 mg/day in pregnancy and adolescents often have lower tolerances (EFSA Scientific Opinion, 2015), so one 300 mg can would exceed the pregnancy guidance and approach or exceed suggested per-day amounts for younger people (source: EFSA 2015).

If you want a quick check tailored to your schedule, try our last-cup calculator (latest cup before bedtime) or run a personalized half-life estimate with the caffeine half-life calculator (half-life calculator); both tools use the same decay model that produced the numbers on this page.

Within the energy-drink category this 473 ml Reign at 300 mg sits at the high end of the products we list: it matches Bang 473 ml = 300 mg and exceeds Monster 473 ml = 160 mg, Rockstar 473 ml = 160 mg, NOS 473 ml = 160 mg, and Monster Ultra 473 ml = 150 mg (all numbers from our dataset). That means Reign and Bang are among the strongest commonly available 473 ml energy cans in our dataset.

Compared with coffee, the can delivers roughly 3.1× the caffeine of a 240 ml drip coffee at 96 mg per 240 ml (TrackCaffeine dataset), so one Reign is equivalent to the caffeine in about three cups of drip coffee (source: TrackCaffeine dataset). Use the side-by-side comparison tool (compare drinks) to see how these values line up against specific coffee servings and other energy drinks in the dataset.

Because the same caffeine mass can come in different volumes, concentration matters for speed of ingestion: Reign contains 63.4 mg per 100 ml (TrackCaffeine dataset), which is a higher concentration than many sodas and some energy alternatives in the dataset.

What changes the number for Reign

The label value 300 mg applies to the standard 473 ml Reign can as recorded in our dataset (TrackCaffeine dataset). Energy-drink caffeine content is determined at manufacture and reported per can; changing can size or switching to a different product variant changes the absolute milligrams on the label (fact: size and formulation determine mg, source: TrackCaffeine dataset).

Not all products with the same brand name or look have the same caffeine. For context, in our dataset other energy drinks of the same volume include Monster Energy 473 ml = 160 mg and Monster Ultra 473 ml = 150 mg, while Bang 473 ml = 300 mg (all values in our dataset), so formulation choices produce large differences in milligrams per can.

Manufacturing, batch variation and measurement method also affect published numbers: lab assays, rounding on nutrition labels, and regional formulations can yield different reported mg even for the "same" product (observed differences are documented in the TrackCaffeine dataset). To see side-by-side numbers for similar products consult the comparison tool (compare drinks), which draws on the same underlying dataset.

• Examples from our data: Red Bull (250 ml) = 80 mg; Monster (473 ml) = 160 mg; Bang (473 ml) = 300 mg (values from TrackCaffeine dataset).

There is no single global law that forces identical mg across markets, so the 300 mg figure should be read as the dataset entry for the commonly sold 473 ml can rather than an absolute universal constant (source: TrackCaffeine dataset).

Where this figure comes from

The 300 mg figure is the value recorded for a 473 ml can in our open dataset (TrackCaffeine dataset), which aggregates label values and published product specifications; we display the dataset entry and flag when manufacturer updates or independent lab results change the number (source: TrackCaffeine dataset).

Published values can disagree because manufacturers publish label amounts with rounding, regional formulations differ, and independent assays use different analytical methods; we will update this page if the manufacturer revises the label or if a peer-reviewed assay reports a different mass for the same can size (policy and data provenance: TrackCaffeine dataset).

Bottom line

Bottom line: one 473 ml (16 fl oz) can of Reign contains 300 mg of caffeine, equal to 63.4 mg per 100 ml and about 3.1× a 240 ml cup of drip coffee at 96 mg (values from the TrackCaffeine dataset).

That 300 mg equals 75% of the 400 mg daily guidance for healthy adults (EFSA Scientific Opinion, 2015). Using the TrackCaffeine half-life model (t1/2 = 5.7 h), remaining = 300 × 0.5^(hours/5.7) gives ~208 mg at 3 h, ~145 mg at 6 h, ~100 mg at 9 h and ~70 mg at 12 h after drinking (calculations and dataset source: TrackCaffeine dataset).