Workout Hydration: How Much Water Do You Really Need?

Hydration supports blood flow, temperature control, and muscle function. Even a 2% loss in body weight from fluid loss can lower performance¹ and make exercise feel harder. Staying well-hydrated helps you train harder, last longer, and recover better.

Water isn’t just something you gulp after a workout. It’s part of a hydration strategy that begins before you step into the gym or onto the trail and continues afterward.

How Much to Drink During Your Workout

No one-size-fits-all number exists. Fluid needs during exercise vary with sweat rate, workout intensity, temperature, humidity, clothing, and fitness level. The goal is to replace what you lose and avoid more than about 2% body weight loss from sweat.

General guidelines for most workouts (up to 60 minutes):

• Aim for 4 – 8 ounces (120 – 240 ml) of fluid every 15 – 20 minutes of activity
• Water is typically enough for sessions shorter than about 60 minutes.

Longer or intense workouts (over 60 minutes):

• Consider electrolytes plus water. Adding sodium and a small amount of carbohydrate can help maintain fluid balance, especially in heat.
• A simple sports drink, electrolyte tablets, or low-sugar sports beverage can help replace what’s lost in sweat.

Avoid over-hydrating. Taking in too much fluid can dilute blood sodium and cause exercise-associated hyponatremia, a serious condition seen in long endurance events.

Practical Hydration Strategy

Before Exercise

Start your workout well-hydrated:

• Drink 16 – 20 ounces (500 – 600 ml) about 2 – 3 hours before activity.
• Closer to start time, 7- 10 ounces (200 – 300 ml) about 10 – 20 minutes before helps top up fluid levels.

During Exercise

• Every 15 – 20 minutes, sip 4 – 8 ounces (120 – 240 ml).
• For workouts longer than an hour, rotate water with an electrolyte drink.
• If you sweat heavily or exercise in heat, adjust upward within that range.

After Exercise

Recovery hydration matters:

• A rough target is to replace all fluid lost during exercise. Weighing before and after exercise can help estimate losses. For each pound lost, aim to drink about 1.25 to 1.5 liter of fluid for every 1 kg of body weight lost.²
• Including a small snack or balanced meal with fluids helps with recovery.

How to Know You’re Hydrated

Thirst isn’t the best indicator. By the time you feel thirsty, you may already be mildly dehydrated.³

Better signs of good hydration:

• Pale yellow urine
• Regular bathroom trips during the day
• Easy endurance and focus during training

Warning signs of dehydration:

• Dark urine
• Fatigue or dizziness
• Muscle cramps
• Lower performance than normal 

1. American College of Sports Medicine et al. “American College of Sports Medicine position stand. Exercise and fluid replacement.” Medicine and science in sports and exercise vol. 39,2 (2007): 377-90. https://doi.org/10.1249/mss.0b013e31802ca597
2. Thomas, D Travis et al. “Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance.” Journal of the Academy of Nutrition and Dietetics vol. 116,3 (2016): 501-528. https://doi.org/10.1016/j.jand.2015.12.006
3. Popkin, Barry M et al. “Water, hydration, and health.” Nutrition reviews vol. 68,8 (2010): 439-58. https://doi.org/10.1111/j.1753-4887.2010.00304.x