Frequently Asked Questions about Caffeine in Diet Coke How much caffeine is in Diet Coke? Diet Coke contains approximately 46mg of caffeine per 12 fluid ounces. However, do keep in mind that caffeine content may vary slightly depending on the bottling location and manufacturing process. For more detailed and up-to-date information, you can visit the official Coca-Cola Product Facts website. Is Diet Coke caffeine-free? No, Diet Coke is not caffeine-free. As mentioned earlier, it contains approximately 46mg of caffeine per 12 fluid ounces. If you’re looking for a caffeine-free alternative, consider trying Coca-Cola’s caffeine-free beverages. You can find more information…