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
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Weight | Units: kg, lb, st, g |
| Exercise per day | In min |
| Climate | Choose one: Temperate, Hot or humid |
| Pregnant or breastfeeding | Choose 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) |
|---|---|
| 35 | 1.6 |
| 52.5 | 2.2 |
| 70 | 2.8 |
| 87.5 | 3.4 |
| 105 | 4 |
| 140 | 5.3 |
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.
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)
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.
Frequently asked questions
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.