# Water Intake Calculator (How Much Water to Drink)

URL: https://speedycalculator.com/calculators/health/water-intake/
Last updated: 2026-10-30

> The water intake calculator estimates how much water you should drink each day from your weight, activity and climate, and compares it with the adequate intake for total water from food and drinks set by the US National Academies and EFSA.

## Inputs

- Sex
- Weight (kg, lb, st, g)
- Exercise per day (min)
- Climate
- Pregnant or breastfeeding

## Results

- Recommended daily fluid
- …in 8-oz cups
- Total water AI from food and drinks (US)

## Formula

```
Baseline ≈ 35 mL per kg of body weight
+ about 350 mL (12 oz) per 30 minutes of exercise
+ 10% in hot weather; + 300 mL in pregnancy; + 700 mL when breastfeeding
AI for total water: men 3.7 L, women 2.7 L (US); 2.5 L and 2.0 L (EFSA)
```

## Explanation

About 20% of your water comes from food, so drinks need to supply the rest. Thirst is a good guide for most healthy people; needs rise with exercise, heat, fever, pregnancy and breastfeeding. Pale yellow urine is a sign you are drinking enough.

### How to use the Water Intake Calculator

- **Sex**
- **Weight**
- **Exercise per day**
- **Climate**
- **Pregnant or breastfeeding**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter your weight, minutes of exercise a day and conditions.

### Inputs explained

FieldWhat to enterSexChoose one: Male, FemaleWeightUnits: kg, lb, st, gExercise per dayIn minClimateChoose one: Temperate, Hot or humidPregnant or breastfeedingChoose one: No, Pregnant, Breastfeeding

### What each result means

- **Recommended daily fluid** = ([Weight]×35 + [Exercise per day]÷30×350)×[Climate]÷1000 + [Pregnant or breastfeeding]÷1000
- **…in 8-oz cups** = [Recommended daily fluid]×1000÷236.6

### Example values

How the main result changes when **Weight** changes and everything else stays at the example values above:

Weight (kg)Recommended daily fluid (L)351.652.52.2702.887.53.410541405.3
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Sex: Male; Weight: 70 kg; Exercise per day: 30 min; Climate: Temperate; Pregnant or breastfeeding: No.

Results — **Recommended daily fluid = 2.8 L**; …in 8-oz cups = 12; Total water AI from food and drinks (US) = 3.7 L.

## Key terms

- **AI**: Adequate intake.

## FAQ

**How much water should I drink a day?**
Many adults need about 2–3 litres of fluid, depending on size, activity and climate.

**Do coffee and tea count?**
Yes – moderate caffeine does not cause net fluid loss.

**Can you drink too much water?**
Yes – very large amounts can cause dangerously low sodium.


## Sources

- [National Academies – Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005)](https://nap.nationalacademies.org/catalog/10925/)
- [EFSA – Scientific opinion on dietary reference values for water (2010)](https://www.efsa.europa.eu/en/efsajournal/pub/1459)