How much caffeine is in Celsius?

A standard 12 oz can of Celsius has 200 mg of caffeine, and so does Celsius Vibe (Celsius). Celsius Essentials has 270 mg per can, more than two 12 oz Red Bulls at 114 mg each (Red Bull).

A regular Celsius has about as much caffeine as a 20 oz Red Bull. Below, I compare it with other drinks and estimate how much could be left at bedtime.

Celsius vs. Red Bull, Monster, Alani, and coffee

Mg per fl oz is the caffeine divided by the can size. Celsius doesn't list the Essentials can size on that page, so there's no per-ounce figure for it.

What the table shows:

• Per ounce, Celsius and Alani Nu are about 1.7 times as strong as Monster or Red Bull.
• A 12 oz Celsius has about the same caffeine as a 20 oz Red Bull (198 mg) in a can 60% of the size.
• Celsius says to have no more than two 12 oz cans a day, and no more than one Essentials (Celsius). Two cans is 400 mg, the amount the FDA cites as not generally associated with negative effects for most adults.

Estimated caffeine left at bedtime, by when you finish the can

These estimates use the same model as the Onset caffeine calculator: caffeine drops by half every 5 hours, and anything under 5 mg counts as cleared. For one drink:

mg left = mg in the drink x 0.5 ^ (hours since you finished it / 5)

Each row is one can finished at that time, with nothing else that day. Values are rounded to the nearest mg.

Bedtime 10 pm

Bedtime 11 pm

A few things stand out:

• A Celsius finished at noon still leaves an estimated 50 mg at 10 pm. That is about half of an 8 oz coffee.
• A Celsius finished at 4 pm leaves an estimated 87 mg at 10 pm, close to a full 95 mg coffee.
• An 8.4 oz Red Bull finished at 6 pm (46 mg at 10 pm) leaves less than a Celsius finished at noon (50 mg). The size of the can matters as much as the clock.

How long until a can is cleared

Onset counts caffeine as cleared once it is under 5 mg. With a 5-hour half-life, that takes 5 x log2(mg / 5) hours.

So in this model, a 2 pm Celsius is still being counted at 2 pm the next day. If you have one every afternoon, the cans overlap.

If your half-life isn't 5 hours

Five hours is an adult average. The FDA-approved label for caffeine citrate gives an adult half-life of about 5 hours, and the FDA says how much is "too much" varies with body weight, medications, medical conditions, and individual sensitivity.

To show how much the rate changes the answer, here is one 200 mg Celsius finished at 2 pm with a faster and a slower example half-life. The 4 and 7 hour values are examples for comparison, not measured rates for any group.

At 7 hours, the 2 pm can leaves more at midnight (74 mg) than the 5-hour model gives at 10 pm (66 mg).

What studies found about doses this size

No study I found tested Celsius itself. These tested caffeine doses near or above one can.

Gardiner et al. 2023. This meta-analysis pooled 24 studies. Its model put the cutoff at 8.8 hours before bed for a 107 mg coffee and 13.2 hours for a 217.5 mg serve of pre-workout, to avoid a reduction in total sleep time (Sleep Med Rev 2023). A 200 mg Celsius is closer to the pre-workout dose than to the coffee.

A 2025 randomized crossover trial in SLEEP. Twenty-three men took 100 mg or 400 mg at 12, 8, or 4 hours before bed. 100 mg had no significant effect at any of those times. 400 mg, the same as two Celsius cans, delayed sleep onset and changed sleep stages when taken within 12 hours of bed (SLEEP, zsae230). The trial did not test 200 mg.

Drake et al. 2013. Twelve adults took 400 mg at bedtime, 3 hours before, or 6 hours before. Even at 6 hours, measured sleep was more than 1 hour shorter than on placebo (J Clin Sleep Med, PMC3805807). The authors suggested keeping moderate to large doses, including energy drinks, before 5 pm.

The studies don't make the bedtime numbers a safe-or-unsafe line. The tables just show how dose and timing combine in the model. For more on timing, see how many hours before bed to stop caffeine. For how half-life works, see how long caffeine stays in your system.

If you are pregnant, breastfeeding, or take medication, ask your doctor what applies to you.

Check your own day

If you had coffee in the morning and a Celsius after lunch, the two add up. The caffeine calculator shows your day hour by hour. It doesn't list Celsius yet, so pick a 200 mg entry such as Pre-workout or Energy shot to stand in for one can.

To log it every day on your phone, Onset is free on the App Store and uses the same model.

This post is for general information and is not medical advice. Estimates use a 5-hour half-life, and your own response varies.

Sources

• Celsius, Essential Facts (Celsius and Celsius Vibe 200 mg per can, Essentials 270 mg per can; daily serving guidance; checked 2026-10-19)
• Red Bull, How much caffeine is in a can of Red Bull Energy Drink? (8.4 fl oz 80 mg, 12 fl oz 114 mg, 16 fl oz 151 mg, 20 fl oz 198 mg; checked 2026-10-19)
• Monster Energy, Original Green (160 mg caffeine, based on 16 fl oz; checked 2026-10-19)
• Alani Nu, Blue Slush Energy Drink (200 mg caffeine per 12 fl oz serving; checked 2026-10-19)
• FDA, Spilling the Beans: How Much Caffeine is Too Much? (400 mg a day for most adults; 'too much' varies; content current as of 08/28/2024)
• FDA-approved CAFCIT label (2020), adult caffeine half-life about 5 hours
• Gardiner et al. 2023, Sleep Medicine Reviews 69:101764 (meta-analysis; 8.8 h for 107 mg coffee, 13.2 h for 217.5 mg pre-workout) (open-access copy)
• Gardiner et al. 2025, Dose and timing effects of caffeine on subsequent sleep, SLEEP 48(4) zsae230 (PubMed abstract)
• Drake et al. 2013, J Clin Sleep Med 9(11):1195-1200
• Onset caffeine model (5-hour half-life, under 5 mg counts as cleared; coffee 95 mg is an Onset estimate)

Keep reading

See how many hours before bed to stop caffeine, or learn how caffeine half-life works.