Dehydration Level Based on Sweat Rate Calculator

The gold standard is the pre-post exercise weigh method: Weigh yourself naked before exercise (in kg), exercise normally without drinking, towel dry, weigh naked again immediately after. Sweat rate (L/hr) = (pre-weight - post-weight) ÷ exercise hours. Do this 3-5 times in different conditions for an average. Correction: If you drink during exercise, subtract the volume consumed. For example: 75kg pre, 73.5kg post after 1.5hr run with 500mL water = (75 - 73.5 - 0.5) ÷ 1.5 = 1.0 ÷ 1.5 = 0.67 L/hr. This is your baseline sweat rate.

The urine color chart correlates with urine specific gravity and hydration status. Scale: 1 (pale straw, hydrated) to 8 (dark brown, severely dehydrated). Levels: 1-2: well hydrated, 3-4: minimally dehydrated, 5-6: significantly dehydrated, 7-8: severely dehydrated. Reliability: moderate — influenced by vitamins (B-complex turns urine bright yellow), beetroot (pink), medications, and certain foods. Morning urine is naturally darker. For athletes: first morning urine should be level 1-3. Before exercise: aim for 1-2. Supplement with thirst and weight tracking for best accuracy.

Performance decline starts at just 1% body water loss: 1-2% loss = impaired thermoregulation, increased perceived effort, 5-10% reduced endurance. 2-3% loss = decreased strength (-5%), power (-8%), cognitive decline (reaction time slows 10-15%). 3-4% loss = significant strength drop (-10%), cramping risk increases, VO2 max decreases 5-10%. 5%+ loss = heat exhaustion risk, severe performance collapse, medical event risk. Practical rule: lose >2% body weight during exercise = you underhydrated. If you weigh 75kg pre and 73kg post (2.7% loss), you lost ~2L more than you consumed.

Drink to replace 80-100% of fluid lost, but never exceed 1L/hour. General guidelines: Cool conditions (<20°C): 400-800mL/hour. Warm conditions (20-30°C): 600-1,000mL/hour. Hot conditions (>30°C): 800-1,200mL/hour. Practical strategy: Drink 150-250mL every 15-20 minutes (not all at once). Add electrolytes for sessions over 60 minutes. Pre-hydrate: 500mL 2 hours before + 250mL 15 minutes before. Post-exercise: drink 1.25-1.5L for every kg lost. Don't force drink if not thirsty — listen to your body for sessions under 60 minutes.