How Much Water Should You Drink Per Day?

The old advice of eight glasses a day is a simplification. Your actual water needs depend on your body size, activity level and climate. Our calculator works out your personalised recommendation.

How to use the calculator

1. Enter your weight in kg or lb
2. Select your activity level
3. Select your climate (important for South African users)
4. Indicate if pregnant or breastfeeding
5. See your recommendation instantly

How intake is calculated

Baseline: 35ml per kilogram of body weight per day. A 70kg person: 70 x 35ml = 2,450ml = 2.45 litres baseline.

Adjustments:

• Moderate exercise: add 500ml
• Intense exercise: add 1,000ml
• Hot or very hot climate: add 300-500ml
• Pregnancy: add 300ml
• Breastfeeding: add 700ml

Real examples

Office worker in Cape Town, 65kg: Baseline: 2,275ml Moderate summer heat: add 300ml Total: approximately 2.6 litres per day

Gym trainer in Johannesburg, 85kg: Baseline: 2,975ml Intense exercise: add 1,000ml Warm climate: add 300ml Total: approximately 4.3 litres per day

Signs you are not drinking enough

• Dark yellow or amber urine (pale yellow is ideal)
• Infrequent urination (should be every 2-3 hours)
• Afternoon headaches
• Difficulty concentrating or brain fog
• Fatigue not explained by poor sleep
• Dry skin and lips

Tips for drinking more

1. Start with a large glass when you wake up before anything else.
2. Keep water visible. A bottle on your desk is a constant reminder.
3. Drink a glass before every meal.
4. Set hourly reminders until it becomes habitual.
5. Eat water-rich foods: cucumber (96%), watermelon (92%), oranges (86%).

Frequently asked questions

Does tea and coffee count? Yes. Despite popular belief, moderate tea and coffee does contribute to hydration. The diuretic effect of caffeine is weaker than the fluid intake from the drink.

Does my requirement change in summer? Yes significantly. In hot conditions your body loses more water through sweat. A South African summer in Limpopo may require 1-2 extra litres per day.

Does sparkling water count the same? Yes. Sparkling water hydrates identically to still water.

Can I drink too much water? Hyponatremia (water intoxication) is rare and mostly seen in endurance athletes drinking excessively. For most people, drinking to thirst keeps levels healthy.

What is the fastest way to rehydrate? Water with electrolytes (sodium, potassium) rehydrates faster than plain water. Sports drinks, coconut water or a pinch of salt in water all work.