Calculator · Performance Lab
Water Intake Calculator
Recommended daily fluid intake based on body weight and training load — as an honest guideline.
Ergebnis
- Base requirement (~35 ml/kg)
- 2,800ml
- Training add-on (~500 ml/h)
- 0ml
- Recommended daily intake
- 2.8liters
Guideline — adjust by climate, sweat rate and urine color.
Explained
What this calculator does for you
Hydration is one of the most underrated performance levers. Even 2 % dehydration measurably costs strength and focus. For athletes: drink before thirst arrives.
The calculator delivers a guideline based on your body weight (~35 ml/kg) plus a realistic add-on for training losses (~500 ml per hour of intense work).
Truth lives in your body: urine color (pale yellow = good), sweat rate, climate, altitude and salt loss change requirements noticeably.
Science
Scientific background
Common guidelines for adults sit between 30–40 ml/kg per day — depending on activity, climate and diet. We use 35 ml/kg as a sensible midpoint.
Per hour of intense training, most people lose 0.5–1.0 L of sweat. ~500 ml/h is a conservative estimate.
During very long efforts, heat or heavy sweating, electrolytes (especially sodium) matter — plain water can otherwise become diluting.
Examples
Practical examples
80 kg, no training
Base ~2,800 ml/day — rounded ~2.8 liters.
80 kg, 90 minutes of lifting
Base 2,800 ml + 750 ml training add-on = ~3.55 liters.
Avoid these
Common mistakes
- 01Only drinking when thirsty — thirst is a late signal.
- 02Ignoring training losses. A hard session can cost 1+ L.
- 03Extreme overhydration. More isn't better — spread it instead of flooding.
- 04In heat or sweat: water-only without sodium can dilute electrolytes.
Recommendations
Further recommendations
- 01Drink across the day, not in 2–3 big sessions.
- 02Keep a bottle visible at your desk — seen is sipped.
- 03For long or hot training: water + a pinch of salt or a simple electrolyte.
- 04With kidney or heart conditions, pregnancy or medication: clear it with a doctor.
FAQ
Frequently asked questions
- Are 2 liters/day enough?
- For a 60 kg sedentary person — barely. For 90 kg with training: not enough. Scale with body weight and activity.
- Do tea and coffee count?
- Yes. The old 'coffee dehydrates' claim doesn't hold for normal amounts. Water stays the clean base.
- What about electrolytes?
- Useful when sweating heavily (>1 h, heat). A pinch of salt in a large bottle often does the job — no expensive sports mixes needed.
- Can you drink too much?
- Yes. Very high amounts in a short period can dangerously dilute sodium (hyponatremia). Drink moderately and spread it out.
- How do I know I'm hydrated?
- Pale-yellow urine, no persistent thirst, stable energy. Very dark = too little. Completely clear = often too much.
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Knowledge Hub
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