How SnapWaterCalc calculates your water intake (SnapWater Method™ v1.0)

Weight-based baseline (33 ml/kg) adjusted for biological sex, activity level and climate, aligned with EFSA and U.S. National Academies reference intakes.

Formula: daily_ml = weight_kg × 33 × sex_factor × activity_factor + climate_add + heavy_sweater_add.

Adjustments

  • Baseline: 33 ml/kg body weight (NAP 2005).
  • Sex factor: male 1.0×, female 0.9× (EFSA 2010).
  • Activity: sedentary 1.0× → very active 1.5× (ACSM 2007).
  • Climate: +0 to +800 ml/day cool → very hot (Sawka 2005).
  • Heavy sweater: +400 ml/day.

Sources

  • U.S. National Academies of Sciences, Engineering, and Medicine (2005): Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate
  • European Food Safety Authority (EFSA) (2010): Scientific Opinion on Dietary Reference Values for water
  • American College of Sports Medicine (2007): ACSM Position Stand: Exercise and Fluid Replacement
  • World Health Organization (2005): Nutrients in Drinking Water
  • American Journal of Clinical Nutrition (2016): A randomized trial to assess the potential of different beverages to affect hydration status (BHI)
  • Nutrition Reviews (Sawka, Cheuvront, Carter) (2005): Human water needs