How Much Water Do Youth Athletes Need?

Helping young athletes stay hydrated is one of the simplest ways to support their health, safety, and performance.

Water plays a key role in everything from focus and mood to muscle function and body temperature. When kids are active, their bodies rely on sweating to cool down, and that means they need to replace lost fluids regularly, especially in heat and/or altitude.

Here, registered dietitian and TrueSport Expert, Stephanie Miezin, MS, RD, CSSD, explains how to best determine your athlete’s daily fluid needs depending on their environment, activity, and fluid preferences.

Start with Daily Needs

Every young athlete needs a certain amount of fluids each day, even before you factor in sports or exercise. General daily guidelines include:

• Ages 4–8: About 56 ounces (7 cups)
• Ages 9–13: About 72–80 ounces (9–10 cups)
• Ages 14–18: About 72–112 ounces (9–14 cups)

Water should make up most of this intake, but other drinks like milk, sports drinks, juice, smoothies, and soups also contribute to hydration. The goal is steady hydration throughout the day—not just downing fluids right before practice or a competition.

Add Fluids for Activity

Exercise increases fluid needs, especially during long practices, games, or hot weather. Athletes need to replace what they lose through sweat.

Sweat rates vary widely, but general estimates are good to know:

Younger athletes may lose about 11–25 ounces per hour
Teen athletes may lose significantly more, sometimes up to 90 ounces per hour in intense or hot conditions

Because every athlete is different, encourage kids to start with small, regular sips during activity and adjust based on how they feel and how much they sweat.

For older athletes, sweat loss can be estimated by weighing before and after exercise, but for younger athletes, this should be done carefully—if at all—to avoid creating an unhealthy focus on body weight.

For more information on calculating sweat rates, visit the hydration section of the Nutrition Guide.

Avoid Over- or Under-Hydrating

The goal is to replace fluids lost—not exceed them. Drinking too little can lead to dehydration, while drinking too much may cause discomfort like a feeling of heaviness or ‘sloshing’ in the gut.

Hydration matters most during:

Long or intense activities (like tournaments or endurance events)
Hot or humid environments
High altitude conditions