PepsiCo
How much caffeine is in Diet Mountain Dew?
Data checked against the source on 2026-10-03 by Oleksii Y.
One 12 fl oz can (360 ml) of Diet Mountain Dew has 54 mg of caffeine, according to PepsiCo Product Facts.
How Diet Mountain Dew compares
- Strength: 15 mg per 100 ml.
- One 12 fl oz can (360 ml) has as much caffeine as about half a cup of brewed coffee, which has 94.8 mg per 8 fl oz cup.
- Of the 22 other sodas in our soda chart, 0 have more caffeine per serving and 21 have less.
How much will be left at bedtime?
1 × 12 fl oz can (360 ml) of Diet Mountain Dew
Left at 11:00 PM (8 h later), average metabolism
≈ 18 mg
Range 9–27 mg (fast to slow metabolism)
To be at 50 mg or less by bedtime, have 54 mg by 9:42 PM (average) or 9:22 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
How long does Diet Mountain Dew 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 12 fl oz can (360 ml) of Diet Mountain Dew (54 mg), about 27 mg is still in your body 5 hours later and about 14 mg after 10 hours. If you clear caffeine slowly (an 8-hour half-life), about 23 mg is left after 10 hours.
Estimated caffeine left at 11:00 PM from one 12 fl oz can (360 ml) (54 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) | ≈ 7 mg | 2–15 mg |
| 12:00 PM (11 h before bed) | ≈ 12 mg | 4–21 mg |
| 3:00 PM (8 h before bed) | ≈ 18 mg | 9–27 mg |
| 6:00 PM (5 h before bed) | ≈ 27 mg | 17–35 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 7 servings.
- Up to 200 mg at one time for healthy adults (EFSA): about 3 servings in one go.
- Up to 200 mg a day in pregnancy (EFSA, NHS): about 3 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
Diet Mountain Dew lists the same 54 mg per 12 fl oz as regular Mountain Dew.
Diet Mountain Dew vs other Mountain Dew drinks
- Mountain Dew: Diet Mountain Dew has the same amount of caffeine as Mountain Dew per 12 fl oz can (360 ml): 54 mg vs 54 mg.
- Mtn Dew Kickstart Orange Citrus: Diet Mountain Dew has less caffeine than Mtn Dew Kickstart Orange Citrus per 12 fl oz can (360 ml): 54 mg vs 69 mg.
Common questions
How much caffeine is in Diet Mountain Dew?
PepsiCo Product Facts gives 54 mg of caffeine per 12 fl oz can (360 ml).
How many Diet Mountain Dew 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 54 mg per 12 fl oz can (360 ml), that is about 7 servings if Diet Mountain Dew is your only source. In pregnancy the reference is 200 mg a day.
How late can I drink Diet Mountain Dew?
With an 11:00 PM bedtime, our model suggests having one serving by about 9:42 PM for average metabolism, or 9:22 PM if you clear caffeine slowly. This is an estimate, not a rule.
Does Diet Mountain Dew have more caffeine than Mountain Dew?
Diet Mountain Dew has the same amount of caffeine as Mountain Dew per 12 fl oz can (360 ml): 54 mg vs 54 mg.
How long does Diet Mountain Dew stay in your system?
Of the 54 mg in one 12 fl oz can (360 ml), roughly 27 mg remains after 5 hours and 14 mg after 10 hours with our average 5-hour half-life. From fast to slow metabolism, 10 hours later it is between 5 and 23 mg.
Where the number comes from
- Diet Mountain Dew - 12 fl oz (ready to drink). PepsiCo Product Facts. Nutrition facts: "Serving Size 12 fl oz (360 mL)", "Caffeine 54mg" Accessed 2026-10-02. Source ↗
- Mountain Dew - 12 fl oz. PepsiCo Product Facts. GTIN 00012000000850, nutrition facts: "Caffeine 54mg" 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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