Mountain Dew Zero Sugar has the most caffeine of the three at 68mg per 12 oz can, Mountain Dew sits in the middle at 54mg, and Diet Mountain Dew has the least at 54mg. The servings are identical, so the per-can numbers settle it outright: a 14mg spread from top to bottom.
Mountain Dew vs Diet Mountain Dew vs Mountain Dew Zero Sugar: the numbers
| Mountain Dew | Diet Mountain Dew | Mountain Dew Zero Sugar | |
|---|---|---|---|
| Caffeine per serving | 54mg per 12 oz can | 54mg per 12 oz can | 68mg per 12 oz can |
| Caffeine per fl oz | 4.5mg | 4.5mg | 5.7mg |
| Servings to reach 400mg (FDA context) | 7.4 | 7.4 | 5.9 |
Sources: Mountain Dew is 54mg per 12 oz can per Caffeine Informer (source), and the figure is carried in our Mountain Dew guide; Diet Mountain Dew is 54mg per 12 oz can per Caffeine Informer (source), and the figure is carried in our the caffeine database; Mountain Dew Zero Sugar is 68mg per 12 oz can per Caffeine Informer (source), and the figure is carried in our Mountain Dew Zero Sugar guide.
What a 14mg spread actually feels like
All three come in the same 12 oz can, so the gap is the whole difference. 14mg is less than half a cup of brewed coffee, which is the easiest way to size it if you already know your coffee tolerance. Switching from Diet Mountain Dew to Mountain Dew Zero Sugar once a day changes your weekly intake by about 98mg.
The three head-to-head pages
Each pairing has its own page with the full math:
- Mountain Dew vs Diet Mountain Dew, head to head
- Mountain Dew vs Mountain Dew Zero Sugar, head to head
Which one should you pick?
Take Diet Mountain Dew when you want the smallest dose of the three, Mountain Dew when you want a middle number without thinking about it, and Mountain Dew Zero Sugar when you actually want the 68mg and know how you handle it. If you drink more than one caffeinated thing a day, the useful move is adding the day up against the 400mg reference rather than judging each drink alone.
For context, the FDA cites 400mg of caffeine a day as an amount generally not associated with negative effects in healthy adults. Tolerance and health vary, so treat these numbers as information, not advice.
Related reading
- The verified caffeine database
- Every drink compared: the comparisons index
- Compare any two of 120+ drinks
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FAQ
Which has the most caffeine, Mountain Dew, Diet Mountain Dew or Mountain Dew Zero Sugar? Mountain Dew Zero Sugar, at 68mg per 12 oz can. Mountain Dew has 54mg per 12 oz can and Diet Mountain Dew has 54mg per 12 oz can.
Which of the three is strongest per ounce? Mountain Dew Zero Sugar, at about 5.7mg per fluid ounce, ahead of Mountain Dew at 4.5mg and Diet Mountain Dew at 4.5mg.
How many Mountain Dew Zero Sugar servings reach the FDA 400mg reference? About 5.9 of them, at 12 oz can each. The FDA cites 400mg a day as an amount generally not associated with negative effects in healthy adults. This is information, not advice.
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