Calculate your daily water intake needs based on weight, activity level, and climate for proper hydration.
Baseline daily water intake at ~0.5 oz per pound of body weight (~30 mL/kg), excluding additional needs from exercise, heat, or illness. Use the calculator above for personalized numbers:
| Body weight | oz / day | Cups (8 oz) | Liters | Notes |
|---|---|---|---|---|
| 100 lb (45 kg) | 50 oz | 6.25 | 1.5 L | Sedentary baseline |
| 130 lb (59 kg) | 65 oz | 8.1 | 1.9 L | Sedentary baseline |
| 150 lb (68 kg) | 75 oz | 9.4 | 2.2 L | Sedentary baseline |
| 175 lb (79 kg) | 88 oz | 11.0 | 2.6 L | Sedentary baseline |
| 200 lb (91 kg) | 100 oz | 12.5 | 3.0 L | Sedentary baseline |
| 250 lb (113 kg) | 125 oz | 15.6 | 3.7 L | Sedentary baseline |
Baseline ~0.5-1 oz per lb of body weight. Add 12 oz (350 mL) per 30 min of exercise, more in hot weather or at altitude. Reference: IOM Dietary Reference Intakes (2004) — 3.7 L/day men, 2.7 L/day women total water from all sources.
Start with 33ml per kg of body weight — a standard medical recommendation.
Exercise increases water loss through sweat. Active people need 15-50% more.
Hot climates, pregnancy, and illness all increase water requirements.
Cross-checked against authoritative formulas (IRS, NIST, ACSM) and updated for 2025/2026 tax years and rates.
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Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.