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Health & fitness·Nutrition

Water Intake Calculator

Calculate how much water you should drink per day based on your weight, activity level, and climate. See results in liters, oz, and number of glasses.

Added May 26, 2026

Quick examples

Input

Result

Enter a value for body weight to see your result.

How it works

Calculate your personalised daily water intake recommendation based on body weight, activity level, and climate. Results are shown in liters, ml, fluid ounces, and number of glasses or bottles.

Step by step

  1. 01Enter your body weight and select kg or lbs.
  2. 02Choose your activity level — from sedentary to intense daily training.
  3. 03Select your climate (hot climates and outdoor work significantly increase needs).
  4. 04The calculator uses the 30–35 ml/kg base formula and adds activity and climate adjustments to give your personalised target.

Examples

70 kg moderately active adult in temperate climate

A 70 kg person doing moderate exercise needs about 2.8 L (roughly 12 glasses) per day — more than the generic '8 glasses' advice, which assumes sedentary adults.

Inputs

Body weight:
70
Unit:
kg
Activity level:
moderate
Climate:
temperate

Result

Daily water target (liters):
2.8 L
8 fl oz glasses:
~12 glasses
Note: These are estimates for total fluid intake including all beverages and water from food (which contributes roughly 20%). For pure water targets, subtract ~0.4–0.6 L. Illness, pregnancy, breastfeeding, or high-altitude environments require additional water. Consult a healthcare provider for medical guidance. Urine color is a practical guide: pale yellow (lemonade color) indicates good hydration; dark yellow or amber means drink more.

Related guides

  • How Much Water Should You Drink Per Day?

    Evidence-based daily water intake targets based on body weight, activity level, and climate. Covers the 8-glasses myth, hydration signs, and what counts toward.

Frequently asked questions

How much water should I drink per day?

General guidance: 30–35 ml per kg of body weight per day as a baseline, adjusted for activity and climate. A 70 kg moderately active adult needs roughly 2.5–3.0 L total fluids per day. The old '8 glasses (2 L)' rule is a rough minimum for sedentary adults.

Does coffee and tea count toward daily water intake?

Yes. Despite mild diuretic effects, caffeinated drinks still contribute net fluid to your daily intake. Studies show that moderate coffee and tea consumption (up to 4–5 cups/day) does not cause dehydration in regular drinkers.

How do I know if I'm drinking enough water?

The simplest check is urine color. Pale yellow (like diluted lemonade) indicates good hydration. Dark yellow or amber means you need more water. Clear urine can mean you're overhydrating, which is also something to avoid.

Does weight affect how much water you need?

Yes. Larger bodies have more cells and a higher metabolic rate, requiring more fluid. The per-kg formula (30–35 ml/kg) accounts for this. An 100 kg person needs significantly more water than a 60 kg person even at the same activity level.