Water Intake Calculator
Calculate daily water intake based on body weight, activity level, and climate with personalized hydration recommendations.
Your profile
Updates as you typeYour drinking schedule
Evenly paced across 16 waking hours| Time | Cup | Cumulative | Note |
|---|
Formula
- T
- Total daily water intake (mL)
- W
- Body weight in kilograms
- Bage
- Per-kg base rate: 35 mL (<30 yrs), 33 mL (30–55), 30 mL (55+)
- Aactivity
- Activity bump: 0 / 250 / 500 / 1000 / 1500 mL
- Eenv
- Environment adjustment: smooth curve on temperature × humidity
- Llife
- Pregnancy +300 mL, breastfeeding +700 mL (EFSA)
- Base rate for age = —
- W × Bage = —
- Activity = —
- Environment = —
- Life stage = —
- Total T = —
Sources: EFSA Panel on Dietetic Products (2010) — adequate intake 2.0 L women / 2.5 L men; U.S. IOM (2005) — 2.7 L / 3.7 L total water. Per-kg base uses the commonly cited 30–35 mL/kg nutrition range. Exercise additions follow ACSM position stand (400–800 mL per hour of training), and heat additions follow NATA fluid-replacement guidance. Treat the number as a starting point — your urine colour and thirst are the real feedback loop.
Examples
How It Works
Base calculation: Your body weight in kilograms is multiplied by 33 mL (the midpoint of the standard 30-35 mL/kg guideline). For a 70 kg person, the base is 2,310 mL.
Activity adjustment: Exercise increases water loss through sweat. The calculator adds 250-1,500 mL depending on your activity level — from light exercise (250 mL) to very active (1,500 mL).
Climate adjustment: Hot and dry climates increase water loss. The calculator adds 250-500 mL based on your environment.
Results are shown in milliliters, ounces, liters, and standard glasses (250 mL / 8 oz). An hourly intake recommendation divides your total by 16 waking hours.
Tips & Best Practices
Frequently Asked Questions
Why does the calculator use 33 mL per kg?
The widely accepted guideline is 30-35 mL per kilogram of body weight per day. The calculator uses 33 mL/kg as the midpoint, then adjusts upward for activity and climate factors.
Does coffee count toward my water intake?
Yes, moderate coffee and tea consumption counts toward hydration. While caffeine has a mild diuretic effect, the water in these beverages still contributes to your daily total.