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How Much Water Should I Drink?

Staying hydrated is crucial to powering your workouts and maintaining a healthy weight. Use this calculator to find out how many cups of water you should drink each day.

Water Intake Calculator

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Water is essential for survival. It keeps your organs functioning properly, particularly your kidneys. Drinking enough water also aids digestion, and it can even increase your calorie burn.[1]

When you don't drink enough water, your athletic potential is also reduced. Even slight dehydration can cause a major decrease in performance.[2] If your body isn't getting the fluids it needs, you won't be able to push hard in the gym and get after those gains.

If you sweat a lot because of exercise intensity or heat, you may want to consider taking supplemental electrolytes to replace the minerals you lose through perspiration. Electrolyte tablets that dissolve in water do the job well, plus they add flavor so it's more appealing to drink up.


The National Academy of Sciences recommends drinking about 11 cups of water per day for women and 16 cups a day for men.[3] But this number can vary based on lifestyle, body size, and other factors. If you're active, you'll need to increase your daily water intake. Variables such as living in a hot climate or wearing a heavy sweater can also increase your hydration needs.

Keep in mind that you don't have to just drink plain water to stay hydrated. Fluids from other drinks, like protein shakes, BCAA drinks, coffee, and smoothies also count toward your water intake requirement. You also get water from foods, especially fruits, vegetables, and dishes like soup.


Drinking extra water can boost calorie burn, helping you to lose weight. However, the effect is modest. You'd have to drink 8 extra cups of water per day to increase your calorie burn by 100 calories, with cold water giving the best boost.[1] Keeping your kidneys happy so you don't retain excessive water weight is the most noticeable weight-loss benefit of staying hydrated.

Another important weight-loss benefit of water is that staying hydrated can help you feel full. Oftentimes, you'll think you're hungry when you're really just dehydrated. Try drinking some water before reaching for a snack, then see if you're still hungry. Downing a couple glasses of water before meals can also cause you to eat less.[4]

Since staying hydrated can help you work out longer and harder, you'll get more out of your gym sessions and maximize your calorie burn. But you need to drink water throughout the day, not just at the gym! Taking in adequate fluids throughout the day will ensure you're already hydrated when you begin your workout. This is especially important if you work out first thing in the morning, before you've had a chance to chug a bunch of water.


Drinking too much water can result in hyponatremia, a condition in which you don't have enough sodium in your blood. Hyponatremia can be serious and even fatal, but it's rare—you'd have to down gallons of water at a time.[5] That's a lot, so don't worry about it. Focus instead on getting enough fluids, which is a much more common challenge.


  1. Boschmann, M., Steiniger, J., Hille, U., Tank, J., Adams, F., Sharma, A. M., ... & Jordan, J. (2003). Water-induced thermogenesis. The Journal of Clinical Endocrinology & Metabolism, 88(12), 6015-6019.
  2. Sawka, M. N., & Montain, S. J. (2000). Fluid and electrolyte supplementation for exercise heat stress. The American Journal of Clinical Nutrition, 72(2), 564s-572s.
  3. Campbell, S. (2004). Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate. Clinical Nutrition Insight, 30(6), 1-hyhen.
  4. Parretti, H. M., Aveyard, P., Blannin, A., Clifford, S. J., Coleman, S. J., Roalfe, A., & Daley, A. J. (2015). Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT. Obesity, 23(9), 1785-1791.
  5. Gardner, J. W. (2002). Death by water intoxication. Military Medicine, 167(5), 432.