The amount of caffeine in the human body has a half-life of 6 hours. An 8 ounce cup of coffee contains approximately 95 mg of caffeine. If you drink the cup of coffee, how long will it take your body to reduce the amount of caffeine to 10 mg.?

You can check the answer of the people under the question at Quora “half life of caffeine in coffee“

95 mg reduces by half every 6 hours. The desired reduction is from 95 to 10.

A factor of 95/10 = 9.5 has a logarithm of .9777, divide by the logarithm of 2 = .30103

and you get 3.2479 halflives x 6 hours = 19.5 hours

You divide by 2 every 6 hours . So 47.5 mg after 6 hours , 23.75 mg after 12 hours , 11.87 mg after 18 hours .

so about 20 hrs, but the half lifff egg is more about 4 hrs. I believe