Red Bull
How much caffeine is in Red Bull Sugarfree?
Data checked against the source on 2026-10-03 by Oleksii Y.
One 8.4 fl oz can of Red Bull Sugarfree has 80 mg of caffeine, according to Red Bull (US).
How Red Bull Sugarfree compares
- Strength: 32 mg per 100 ml.
- One 8.4 fl oz can has as much caffeine as about three quarters of a cup of brewed coffee, which has 94.8 mg per 8 fl oz cup.
How much will be left at bedtime?
1 × 8.4 fl oz can of Red Bull Sugarfree
Left at 11:00 PM (8 h later), average metabolism
≈ 26 mg
Range 13–40 mg (fast to slow metabolism)
To be at 50 mg or less by bedtime, have 80 mg by 6:52 PM (average) or 4:50 PM (slow metabolism).
What sleep studies found near this dose
- Gardiner et al. 2025 (randomized trial): In 23 healthy young men, 100 mg taken 12, 8 or 4 hours before bed had no significant effect on measured or self-rated sleep.
- Gardiner et al. 2023 (meta-analysis): To avoid losing sleep time, the authors suggest a coffee (107 mg per 250 ml) at least 8.8 hours before bed.
Estimate from a simple model: half-life of 3, 5 or 8 hours, 50 mg bedtime target. How we calculate
Caffeine by size
| Serving | Caffeine |
|---|---|
| 8.4 fl oz can | 80 mg |
| 12 fl oz can | 114 mg |
| 16 fl oz can | 151 mg |
| 20 fl oz can | 198 mg |
How long does Red Bull Sugarfree stay in your system?
Our model halves caffeine every 5 hours for average metabolism, and every 3 or 8 hours for fast or slow metabolism. From one 8.4 fl oz can of Red Bull Sugarfree (80 mg), about 40 mg is still in your body 5 hours later and about 20 mg after 10 hours. If you clear caffeine slowly (an 8-hour half-life), about 34 mg is left after 10 hours.
Estimated caffeine left at 11:00 PM from one 8.4 fl oz can (80 mg), using a half-life of 5 hours for average metabolism and 3 to 8 hours for the range. How we calculate
| Had at | Left at bedtime (average) | Range |
|---|---|---|
| 8:00 AM (15 h before bed) | ≈ 10 mg | 3–22 mg |
| 12:00 PM (11 h before bed) | ≈ 17 mg | 6–31 mg |
| 3:00 PM (8 h before bed) | ≈ 26 mg | 13–40 mg |
| 6:00 PM (5 h before bed) | ≈ 40 mg | 25–52 mg |
How many fit in a day?
Reference amounts are for caffeine from all sources combined. Counted at the upper end of the stated amount, one serving at a time:
- Up to 400 mg a day for most healthy adults (FDA, EFSA): about 5 servings.
- Up to 200 mg at one time for healthy adults (EFSA): about 2 servings in one go.
- Up to 200 mg a day in pregnancy (EFSA, NHS): about 2 servings.
These are reference amounts for groups of people, not a personal limit. Some people feel jittery or sleep worse on much less. See the cutoff calculator for timing.
Good to know
Red Bull states that Red Bull Zero and Red Bull Sugarfree contain the same functional ingredients.
Red Bull Sugarfree vs other Red Bull drinks
- Red Bull Energy Drink: Red Bull Sugarfree has the same amount of caffeine as Red Bull Energy Drink per 8.4 fl oz can: 80 mg vs 80 mg.
Common questions
How much caffeine is in Red Bull Sugarfree?
Red Bull (US) gives 80 mg of caffeine per 8.4 fl oz can. Other sizes are in the table on this page.
How many Red Bull Sugarfree servings can I have in a day?
The FDA and EFSA cite up to 400 mg of caffeine a day, from all sources combined, for most healthy adults. At 80 mg per 8.4 fl oz can, that is about 5 servings if Red Bull Sugarfree is your only source. In pregnancy the reference is 200 mg a day.
How late can I drink Red Bull Sugarfree?
With an 11:00 PM bedtime, our model suggests having one serving by about 6:52 PM for average metabolism, or 4:50 PM if you clear caffeine slowly. This is an estimate, not a rule.
Does Red Bull Sugarfree have more caffeine than Red Bull Energy Drink?
Red Bull Sugarfree has the same amount of caffeine as Red Bull Energy Drink per 8.4 fl oz can: 80 mg vs 80 mg.
How long does Red Bull Sugarfree stay in your system?
Of the 80 mg in one 8.4 fl oz can, roughly 40 mg remains after 5 hours and 20 mg after 10 hours with our average 5-hour half-life. From fast to slow metabolism, 10 hours later it is between 8 and 34 mg.
Where the number comes from
- How much caffeine is in a can of Red Bull Sugarfree? Red Bull (US). Answer text, one sentence per can size (8.4, 12, 16 and 20 fl oz). Accessed 2026-10-02. Source ↗
Recipes and labels change. If a number here no longer matches the label, the label wins.
General information, not medical advice
If you feel unwell after caffeine — for example chest pain, a fast or irregular heartbeat that does not settle, fainting, confusion or trouble breathing — get urgent medical help. If you are pregnant or breastfeeding, under 18, take medication, or have a heart, liver or anxiety condition, high blood pressure or a sleep disorder, ask a doctor or pharmacist what amount is right for you.
Sources
- U.S. Food and Drug Administration (2024). Spilling the Beans: How Much Caffeine is Too Much? FDA Consumer Updates. fda.gov ↗
- European Food Safety Authority. Caffeine | EFSA. EFSA topic page (summary of the 2015 Scientific Opinion on the safety of caffeine). efsa.europa.eu ↗
- NHS. Foods to avoid in pregnancy. NHS. nhs.uk ↗
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