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Water Intake Calculator

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Calculate your recommended daily water intake based on weight and activity level

kg
ml
A steel tumbler holds about 250 ml; a common bottle is 1,000 ml.
Water to drink each day
3litres
In millilitres
2,950ml
Glasses of 250 ml
12
Per waking hour
180ml
over about 16 hours
Tea, milk, buttermilk, dal and fruit count towards this too. Pale yellow urine is a good sign you're drinking enough.
If you have kidney or heart disease, or your doctor has limited your fluids, follow their advice instead.
Partml
Base: 70 kg × 35 ml2,450
Activity500
Hot weather0
Total2,950

Runs entirely in your browser. Nothing you type or upload is sent to us or stored.

For general information only, not medical advice. Talk to a doctor or a qualified professional about your health. Terms of use

How to Use

  1. Enter your Body weight in kg, or drag the slider.
  2. Pick your Activity level and your Climate. Exercise and hot, humid weather each add about 500 ml or more.
  3. Set the Glass or bottle size you drink from (a steel tumbler is about 250 ml) to see how many to drink.
  4. The result shows litres a day, the number of glasses or bottles, and roughly how much to drink each waking hour. The table below shows how the total is made up.

Why drinking enough water matters

Water makes up about 60% of the human body. Your body uses it for almost everything: digesting food, moving blood around, keeping your temperature steady, cushioning joints and getting rid of waste. Even mild dehydration, a loss of 1–2% of body water, can affect your physical performance, concentration and mood. This water intake calculator gives you a daily target based on your weight, activity and climate.

General guidelines

PersonRecommended daily intake
Sedentary adult (temperate)~2.0 – 2.5 litres
Active adult (moderate exercise)~2.5 – 3.5 litres
Hot climate / outdoor worker3.5 – 5.0 litres
Pregnant woman+0.3 litres above baseline
Breastfeeding woman+0.7 litres above baseline

Everyday tips

  • Have a full glass of water first thing in the morning, before your tea or coffee.
  • Keep a 1-litre bottle on your desk and try to finish it twice a day.
  • If you tend to forget, set a phone reminder every 2 hours.
  • Eat foods with a lot of water in them: cucumber (96% water), watermelon (92%), tomatoes (95%).
  • For every 30 minutes of exercise, drink at least 200–300 ml to replace what you sweat out.

The urine colour test

This is the easiest check. Your urine should be pale yellow, like straw. Dark yellow or amber means you should drink more. Urine that stays completely clear for long stretches may mean you're drinking too much. Neither extreme is good.

Frequently Asked Questions

About 35 ml per kg of body weight, so roughly 2.45 litres if you weigh 70 kg. The well-known advice is 8 glasses (2 litres) a day, but real needs vary. Exercise, heat, breastfeeding and illness all raise them. The calculator adjusts for your weight, activity level and climate.

Yes. All drinks count, including tea, coffee, milk and juice. The old idea that coffee dehydrates you has largely been disproved, and a cup of coffee still leaves you better hydrated than before. Sugary drinks and alcohol aren't great choices, though. Plain water is still the best.

Dark yellow urine, thirst, a dry mouth and tiredness are the early signs. Moderate dehydration brings headaches, poor concentration and dizziness. Severe dehydration causes a fast heartbeat, confusion and sunken eyes. A quick check: your urine should be pale yellow, like lemonade. Dark amber urine almost always means you need more water.

Yes. Overhydration (hyponatraemia) can happen if you drink far more than your kidneys can handle, which is more than about 1 litre an hour for a long stretch. It's rare in healthy adults but can be dangerous during endurance sports. For most people thirst is a good guide: drink when you're thirsty, and don't force down large amounts.