Calculator

Water Intake Calculator

How much water should you drink per day? Get a personalised recommendation based on your weight, activity level, and climate.

💧 About You
More steps = more sweat = more water needed
litres per day
Fluid ounces
8 oz glasses
500 ml bottles
Base (without activity)

How much water do you really need?

The popular "8 glasses a day" rule is a rough guide, but your true needs depend on your body size, how active you are, and the environment. This calculator uses a research-backed formula adjusted for these factors.

Base formula: Weight (kg) × 0.033 litres. This is then scaled up for activity level, step count, and heat — all of which increase fluid loss through sweat.

Signs of dehydration to watch for

  • Dark yellow urine (aim for pale straw colour)
  • Feeling thirsty — thirst is already a sign you're behind
  • Headaches or difficulty concentrating
  • Reduced walking performance and endurance

Hydration by activity level

ActivityExtra water needed
10,000 steps (moderate)+300–500 ml
1 hour brisk walking+500–700 ml
Hot weather (+10°C above normal)+500–1,000 ml
High altitude (>2,500m)+500 ml

How Much Water Do Active Walkers Really Need?

Your actual hydration needs depend on body size, activity level, and environment. Active walkers need meaningfully more water than sedentary people due to sweat loss and elevated body temperature during exercise.

Daily Water Needs by Activity Level

Activity Level60 kg70 kg80 kg90 kg
Sedentary2.0 L2.3 L2.6 L3.0 L
Light (5k steps)2.2 L2.5 L2.9 L3.3 L
Moderate (10k steps)2.5 L2.9 L3.3 L3.8 L
Active (15k+ steps)2.8 L3.3 L3.7 L4.2 L

Drink 400–600 ml 1–2 hours before a long walk. During walks over 45 minutes, sip 150–250 ml every 15–20 minutes. After your walk, for each 0.5 kg of body weight lost during exercise, drink 500 ml to restore fluid balance.