For athletes
Hydration Calculator for Athletes
Quick answer
Athletes usually need a daily baseline of 35–45 ml per kg of body weight, plus fluid for sweat lost during training. A practical starting point is 0.4–0.8 L per training hour, with electrolytes for long, hot, or salty sessions. Use the calculator below for your daily target, then use a sweat-rate test to personalise workout fluids.
Fine-tuneMeasure in bottles · Your day
Saved profile
Save this setup to resume tomorrow on this browser.
Your daily goal: 118 ounces, 14 glasses.
Your daily goal
Updates instantlyof water a day · about 14 glasses · 7 half-litre bottles
Planning scenarios: 112-139 fl oz. Use it as a flexible target, not a medical limit.
Start
2.5 glasses
7:00 AM
Taper
9:00 PM
for better sleep.
Food fluid
+0.9 L
typical food water
- 3.5
- Litres
- 118
- Ounces
- 14
- Glasses
Why this number
WaterDailyGoal uses 33 ml/kg for a beverage planning estimate. The 30–40 ml/kg scenarios and activity/climate coefficients are site assumptions, not validated personal requirements or NAM/EFSA formulas. Pregnancy, breastfeeding, and GLP-1 medicines do not automatically change this estimate. Population total-water references include food; they are not minimum drinking doses. Follow individual clinical advice.
Full methodologyNext step
Your sip schedule
- 7:00 AM · Start the day2.5 glasses
- 9:48 AM · Top up2.5 glasses
- 12:36 PM · Top up2.5 glasses
- 3:24 PM · Top up2.5 glasses
- 6:12 PM · Top up2 glasses
- 9:00 PM · Wind down2 glasses
Ease off after 9:00 PM for better sleep.
Electrolytes? Consider sweat losses
Electrolytes are not automatic. Long or heavy sweating and vomiting or diarrhea need different approaches; food, losses and medical restrictions matter. Ask a clinician or pharmacist when illness is involved.
A friendly estimate for healthy adults, not medical advice. Your needs rise with heat, exercise, illness, pregnancy, and some medications. Don't drink more than ~1 litre per hour.
Daily goal
118 fl oz
The link and preview image include your weight and settings.
Start with the day, then add the session
Athlete hydration works best in two layers. First, set a normal daily baseline from body weight, activity, and climate. Second, add what you lose in the session. That second number is personal: two runners at the same pace can have very different sweat rates, especially in heat.
Use sweat rate for serious sessions
Weigh yourself before and after a representative workout, track what you drank, and convert the change into litres per hour. That gives you a realistic range for similar workouts, instead of guessing from generic advice. Practice the plan before race day or competition day, when your stomach is under stress.
Electrolytes are situational
Sodium matters when sweat loss is high. Use electrolytes when sessions run past about an hour, when conditions are hot or humid, when your clothes dry with white salt marks, or when plain water leaves you sloshy. For short easy training, normal food usually covers it.
Frequently asked
How much water should athletes drink per day?
Most athletes land around 35–45 ml per kg of body weight per day before sport-specific sweat losses. Add about 0.4–0.8 L per training hour, then refine with a sweat-rate test because sweat loss varies dramatically between athletes.
Should athletes drink electrolytes every day?
Not always. For everyday short sessions, water plus normal meals is usually enough. Electrolytes become useful when workouts are long, hot, humid, very sweaty, or when you finish with salty skin or clothing.
Is clear urine the goal for athletes?
No. Pale yellow is a better everyday target. Completely clear urine all day can mean you are over-drinking, especially if you are also avoiding salt.
Sources
- 1.U.S. National Academies (IOM/NAM), 2005 — Adequate total water intake of about 3.7 L/day for men and 2.7 L/day for women, including water from food and all beverages.Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, Summary: water adequate intakes; drinks and food
- 2.American College of Sports Medicine, Exercise and Fluid Replacement — Athletes should start exercise euhydrated, limit body-mass losses during training, and replace fluid and sodium after heavy sweat losses.
- 3.McDermott et al., NATA Position Statement, 2017 — Sweat rate varies widely by athlete, heat, intensity, clothing, and acclimation, so pre/post body-weight checks are the practical way to individualise fluid plans.National Athletic Trainers’ Association Position Statement: Fluid Replacement for the Physically Active; individualized replacement and overdrinking