Estimate how much water you should drink each day, personalised to your weight, activity and climate.
General guide: The NHS recommends 6–8 glasses (1.5–2 litres) of fluid a day. Use this tool to adjust for your body and lifestyle. This is general information, not medical advice.
Your Details
Your Recommended Daily Water Intake
Litres
0.00 L
UK Pints
0.0
250 ml Glasses
0
How we calculated it
Total recommended intake
0 ml
Suggested hourly plan (waking hours 7am–10pm)
Tips to stay hydrated
Drink a glass of water as soon as you wake up.
Keep a reusable bottle on your desk and refill it 2–3 times during the working day.
Have a glass of water with every meal and snack.
Set reminders on your phone if you tend to forget — once you feel thirsty you are already mildly dehydrated.
Eat water-rich foods such as cucumber, melon, oranges and soups.
Pale, straw-coloured urine is a good sign you are well hydrated; dark yellow means drink more.
Frequently Asked Questions
The NHS Eatwell Guide recommends 6 to 8 glasses (around 1.5 to 2 litres) of fluid per day for adults in a temperate climate. Your actual need varies with body weight, physical activity, temperature and whether you are pregnant or breastfeeding. This calculator estimates a personalised target by adjusting that baseline for those factors.
Yes. Despite the old myth, moderate caffeine intake is not significantly dehydrating. The NHS counts tea, coffee, lower-fat milk, sugar-free drinks and even fruit juice (up to one 150 ml glass per day) towards your fluid intake. Water, however, is the healthiest and calorie-free option.
Yes — although rare, drinking very large volumes of water in a short space of time can dilute blood sodium and cause hyponatraemia. This is mainly a risk for endurance athletes and people with certain medical conditions. For most people, listening to thirst and spreading intake throughout the day is safe.
Exercise increases fluid loss through sweat. A rough guide is an extra 350–700 ml per hour of moderate exercise, and more in hot conditions. For sessions over an hour, intense exercise, or hot weather, an electrolyte drink can help replace lost sodium as well as fluid.
Yes. The NHS suggests pregnant women aim for around 2 litres of fluid a day, and breastfeeding mothers may need an extra 700–1000 ml per day to support milk production. This calculator adds these allowances when you tick the relevant option.