Nutrition
Water Intake Calculator
Dehydration cuts energy, focus, and performance before you even feel thirsty. Get your daily fluid target in litres and glasses.
Daily water need is roughly 30–35 millilitres per kilogram of body weight — about 2.1 litres for a 70 kg adult — before exercise or heat. Needs rise with activity, pregnancy, breastfeeding, and hot climates. Pair the target with whole foods and adjust based on your own progress and energy levels.
Base: 30–35 ml per kg.
Add 500–1,000 ml per workout hour.
Hot climates add 500 ml+.
Calculate Your Water Intake
Your Daily Fluids
What Is Water Intake?
Water regulates temperature, lubricates joints, and transports nutrients. Even 2% dehydration measurably impairs concentration and endurance.
The 30–35 ml/kg rule covers baseline needs; exercise, heat, pregnancy, and breastfeeding all raise the requirement. About 20% of fluids typically come from food.
How It Is Calculated
Fluids (L) = weight (kg) × 30–40 ml/kg ÷ 1000 + climate adjustment
Example: Example: 70 kg, moderate activity, temperate → ≈ 2.3 L/day
Situational adjustments
| Situation | Extra fluids |
|---|---|
| Exercise (per hour) | +500–1,000 ml |
| Hot/humid climate | +500 ml+ |
| Pregnancy | +300 ml |
| Breastfeeding | +700–1,000 ml |
| Illness with fever | +500 ml |
Limitations
- Kidney or heart conditions may require fluid restriction, follow clinical advice.
- Coffee and tea count toward fluids; alcohol works against hydration.
- Thirst is a late signal, drink on a schedule in heat and during sport.
Sources & Review
References used for this calculator’s formulas and thresholds:
Water Intake FAQ
How much water should I drink daily?
About 30–35 ml per kg, roughly 2.1–2.5 L for a 70 kg adult, more with exercise or heat.
Can I drink too much water?
Yes, drinking litres rapidly can dilute blood sodium (hyponatremia). Spread intake through the day; athletes in long events should use electrolytes.
Does tea or coffee count?
Yes, moderate amounts count toward fluids. Alcohol is dehydrating and doesn't.
How do I know if I'm hydrated?
Pale-yellow urine and rare thirst are the practical signs. Dark urine in the afternoon means drink up.
A note before you begin: this tool offers educational estimates only. It cannot replace advice from your doctor or another qualified professional.