Water Intake Calculator for Hot Weather
In temperatures above 35 degrees C, increase your baseline water intake by 1-2 litres. Outdoor workers in 40-degree heat can lose 1-1.5 litres of sweat per hour. A sedentary 70kg person in moderate heat needs about 3-3.5 litres per day versus 2.5 litres in normal weather.
Total per Day
2,950 ml
In Litres
2.95 L
Glasses (250ml)
12 glasses
Hourly Schedule
Spread 2.95L across 16 waking hours = 184ml/hour
About 1 glass every hour
| Component | ml/day |
|---|---|
| Base (35ml × 70kg) | 2450 |
| Activity add-on | +500 |
| Climate add-on | +0 |
| Total | 2950 |
Base recommendation: 35ml per kg of body weight. Additional needs for exercise and heat. Coffee and tea count but alcohol does not. Spread intake throughout the day — avoid drinking large amounts at once.
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Common questions about Water Intake Calculator for Hot Weather
What are early signs of heat-related dehydration?
In heat: dark urine, reduced sweating despite being hot (warning sign of severe dehydration), dizziness on standing, headache, and fatigue coming on faster than expected. Heat exhaustion (heavy sweating, pale skin, fast weak pulse) requires moving to shade and hydrating immediately. Heat stroke (hot dry skin, confusion) is an emergency - call 108.
Should I drink electrolytes in summer?
If sweating heavily for more than 1-2 hours, yes. ORS (Oral Rehydration Salts) or homemade salted lemonade (water, lemon, pinch of salt, pinch of sugar) helps. Plain water in very large amounts without electrolytes can dilute sodium, causing hyponatremia. Coconut water is a good natural electrolyte source.
Do fruits and vegetables count toward water intake?
Yes. Cucumber is 96% water, watermelon 92%, strawberries 91%, and oranges 87%. A diet rich in fruits and vegetables can contribute 20-30% of daily water needs. Studies show people who eat water-rich foods are better hydrated than those relying solely on beverages.