How Much Water Should I Drink?

Daily fluid needs vary from person to person. Body weight, physical activity and weather conditions can all affect how much fluid a person may need during the day.

How Does the Water Intake Calculator Work?

This calculator uses body weight as the starting point and adjusts the estimate for activity level and hot weather conditions. The Advanced version also allows exercise duration and an entered exercise fluid replacement rate to be considered separately.

The result is an estimated daily fluid intake shown in litres, millilitres and US fluid ounces.

Does Body Weight Affect Water Intake?

Body size can affect fluid requirements, which is why body weight is used as one of the inputs in this calculator. The result is an estimate rather than a fixed requirement for every person.

Does Exercise Increase Water Needs?

Physical activity can increase fluid loss, particularly when exercise causes sweating. The Advanced calculator allows exercise duration and a user-entered fluid replacement rate to be included as a separate exercise fluid estimate.

Does Hot Weather Increase Water Needs?

Hot conditions can increase fluid loss through sweating. The calculator uses four temperature ranges: cold below 15°C, normal from 15–29.9°C, hot from 30–34.9°C, and very hot at 35°C or above.

When current weather is enabled, the calculator uses the current apparent temperature to apply the relevant weather adjustment.

Water Intake Calculator FAQs

How much water should I drink each day?

There is no single daily amount that applies to everyone. Fluid needs can vary with body size, activity, temperature, diet and other individual factors. This calculator provides a general estimate.

Is this a daily water requirement calculator?

No. It provides an estimated daily fluid intake rather than a medically prescribed water requirement.

Can the calculator use current weather?

Yes. You can enable the current weather option and allow location access to obtain current weather conditions and adjust the estimate for heat.

What is the difference between the Simple and Advanced calculators?

The Simple calculator uses body weight, activity level and climate or current weather. The Advanced calculator adds sex, exercise duration and an exercise fluid replacement rate for a more detailed estimate.

Does the calculation include water from food?

No. The calculator estimates fluid intake and does not separately calculate water obtained from food.

Is this calculator a medical recommendation?

No. The result is a general estimate. Individual fluid needs can vary because of health conditions, medications, diet, exercise and other factors.