Decaf is 97% caffeine free or 3% caffeine. Regular coffee is only 6% caffeine so, if you think drinking decaf means you’re getting no caffeine you’re quite wrong.
What Is Decaf Coffee?
Decaf coffee is not completely caffeine-free.
While USDA regulations stipulate that decaf should not exceed 0.10 percent caffeine on a dry basis in the package, comparison between brewed regular and decaf coffee shows that decaf appears to have at least 97% of caffeine removed.
To put this into perspective, an average 12-ounce (354-ml) cup of coffee containing 180 mg of caffeine would have about 5.4 mg of caffeine in a decaffeinated state.
https://www.healthline.com/nutrition/caffeine-in-decaf#what-it-is
The difference is not half. It really is 97% less caffeine, and with that, went a little flavor.