How do you know if you’re hydrated? Look at your urine. Sounds weird, but we’re serious. The color of your urine is the easiest way to see if you’re hydrated. Hydration needs vary, but a general rule is half an ounce to an ounce of water per pound of body weight. If you weight 200 pounds, that’s 100-200 ounces a day. Check out this urine chart.