How much caffeine is in Diet Coke (12oz can)?
中文：健怡可口可乐
Caffeine content
46 mg
per 12 fl oz (355 ml)
About this drink
Diet Coke counterintuitively has more caffeine than regular Coke — 46 mg vs 34 mg. The sweeteners differ and the formulation gives a slight caffeine boost. Still mild compared to coffee.
Ingredients: Carbonated water, caramel color, aspartame, phosphoric acid, citric acid, caffeine
When will it clear your system?
46 mg is mild but cumulative if you drink multiple cans. Three Diet Cokes ≈ 140 mg ≈ a Tall Starbucks Latte.
Based on caffeine's 5-hour half-life, a Diet Coke (12oz can) consumed at 2:00 PM drops below the sleep-safe threshold (~20 mg) by approximately 20:00 the same evening.
Where this fits in a daily limit
That's about 23% of the 200 mg pregnancy guideline and 12% of the 400 mg general adult daily limit — comfortably moderate.
See our pregnancy caffeine guide or half-life sleep math for the deep dive.
How it compares
| Drink | Caffeine |
|---|---|
Diet Coke (12oz can) Coca-Cola | 46 mg |
| Coca-Cola (12oz can) Coca-Cola | 34 mg |
| Pepsi (12oz can) Pepsi | 38 mg |
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How much caffeine is in a Diet Coke (12oz can)?
A 12 fl oz (355 ml) Diet Coke (12oz can) contains approximately 46 mg of caffeine. Actual values may range from 46 to 46 mg depending on preparation and source variation.
Is Diet Coke (12oz can) safe during pregnancy?
The current ACOG and NHS guideline is under 200 mg of caffeine per day during pregnancy. A Diet Coke (12oz can) fits comfortably within that limit. Always consult your obstetrician for personalized advice.
When should I stop drinking Diet Coke (12oz can) for sleep?
Caffeine has a 5-hour half-life. To have under 20 mg circulating at bedtime (the typical sleep-safe threshold), stop drinking Diet Coke (12oz can) about 7 hours before sleep. 46 mg is mild but cumulative if you drink multiple cans. Three Diet Cokes ≈ 140 mg ≈ a Tall Starbucks Latte.
Diet Coke (12oz can) vs Coca-Cola (12oz can) — which has more caffeine?
Diet Coke (12oz can) contains 46 mg per serving; Coca-Cola (12oz can) contains 34 mg per 12 fl oz (355 ml). Diet Coke (12oz can) is the stronger of the two.
Does Diet Coke (12oz can) keep you awake?
46 mg is mild caffeine. Most people can drink Diet Coke (12oz can) in the afternoon without notable sleep impact.
Caffeine values shown are typical for the listed serving size. Actual content varies by preparation, brewing method, batch, and brand reformulation. Not medical advice — consult a healthcare provider for personalized guidance.