How much water should I drink before exercise?

As a general guideline, drink 14 oz. – 20 oz. of water 2 - 4 hours before exercise.

To be more specific:

Drink approximately 0.08 oz. – 0.11 oz. of water per pound of body weight.

Example:

Jack weighs 200 lbs
Jack will need to drink 16 oz. - 22 oz. of water 2 - 4 hours before exercise.

Here’s the math:

200 lbs x 0.08 oz. = 16 oz.
200 lbs x 0.11 oz. = 22 oz.

Drink water 2 - 4 hours before exercise so your body has time to absorb it. The American College of Sports Medicine recommends drinking water at least 4 hours before exercise and drinking more 2 hours before exercise if you have not urinated or if your urine is dark.