Monster
How much caffeine is in Monster Zero Ultra?
Data checked against the source on 2026-10-03 by Oleksii Y.
One 16 fl oz can of Monster Zero Ultra has 150 mg of caffeine, according to Monster Energy.
How Monster Zero Ultra compares
- Strength: 32 mg per 100 ml.
- One 16 fl oz can has as much caffeine as about 1.5 cups of brewed coffee, which has 94.8 mg per 8 fl oz cup.
How much will be left at bedtime?
1 × 16 fl oz can of Monster Zero Ultra
Left at 11:00 PM (8 h later), average metabolism
≈ 49 mg
Range 24–75 mg (fast to slow metabolism)
To be at 50 mg or less by bedtime, have 150 mg by 2:20 PM (average) or 9:34 AM (slow metabolism).
What sleep studies found near this dose
- 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.
- Gardiner et al. 2023 (meta-analysis): For a pre-workout serving (217.5 mg), the authors suggest at least 13.2 hours before bed.
Estimate from a simple model: half-life of 3, 5 or 8 hours, 50 mg bedtime target. How we calculate
How long does Monster Zero Ultra 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 16 fl oz can of Monster Zero Ultra (150 mg), about 75 mg is still in your body 5 hours later and about 38 mg after 10 hours. If you clear caffeine slowly (an 8-hour half-life), about 63 mg is left after 10 hours.
Estimated caffeine left at 11:00 PM from one 16 fl oz can (150 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) | ≈ 19 mg | 5–41 mg |
| 12:00 PM (11 h before bed) | ≈ 33 mg | 12–58 mg |
| 3:00 PM (8 h before bed) | ≈ 49 mg | 24–75 mg |
| 6:00 PM (5 h before bed) | ≈ 75 mg | 47–97 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 2 servings.
- Up to 200 mg at one time for healthy adults (EFSA): about 1 serving in one go.
- Up to 200 mg a day in pregnancy (EFSA, NHS): about 1 serving.
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
Monster's Ultra Black page also lists 150 mg of caffeine per 16 fl oz.
Monster Zero Ultra vs other Monster drinks
- Monster Energy (Original Green): Monster Zero Ultra has less caffeine than Monster Energy (Original Green) per 16 fl oz can: 150 mg vs 160 mg.
- Monster Energy Zero Sugar: Monster Zero Ultra has less caffeine than Monster Energy Zero Sugar per 16 fl oz can: 150 mg vs 160 mg.
- Java Monster Mean Bean: Monster Zero Ultra has less caffeine than Java Monster Mean Bean per 100 ml (32 vs 45 mg). Monster Zero Ultra: 150 mg per 16 fl oz can; Java Monster Mean Bean: 200 mg per 15 fl oz can.
Common questions
How much caffeine is in Monster Zero Ultra?
Monster Energy gives 150 mg of caffeine per 16 fl oz can.
How many Monster Zero Ultra 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 150 mg per 16 fl oz can, that is about 2 servings if Monster Zero Ultra is your only source. In pregnancy the reference is 200 mg a day.
How late can I drink Monster Zero Ultra?
With an 11:00 PM bedtime, our model suggests having one serving by about 2:20 PM for average metabolism, or 9:34 AM if you clear caffeine slowly. This is an estimate, not a rule.
Does Monster Zero Ultra have more caffeine than Monster Energy (Original Green)?
Monster Zero Ultra has less caffeine than Monster Energy (Original Green) per 16 fl oz can: 150 mg vs 160 mg.
How long does Monster Zero Ultra stay in your system?
Of the 150 mg in one 16 fl oz can, roughly 75 mg remains after 5 hours and 38 mg after 10 hours with our average 5-hour half-life. From fast to slow metabolism, 10 hours later it is between 15 and 63 mg.
Where the number comes from
- Zero Ultra. Monster Energy. Product page: "150MG … Caffeine content based on 16 fl oz" Accessed 2026-10-02. Source ↗
- Monster Ultra Black. Monster Energy. Product page: "150MG … Caffeine content based on 16 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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