Daily Water Intake Calculator: How Much Water a Day in Singapore

How much water should you drink a day?

About 1.6 to 2.2 L of drinks for a woman and 2.0 to 3.0 L for a man, before exercise. That is the drinks share of the official adequate intakes for total water, which also counts the water in food. Enter your details above for your own figure and the top-up for today's exercise.

Total water is from EFSA's dietary reference values and the US National Academies (NASEM) report on water, sweat rates from NASEM's water chapter and the 2% limit from the American College of Sports Medicine position stand on fluid replacement, all checked 7 November 2026. It is an estimate for healthy adults, not medical advice.

What is the recommended daily water intake?

2.0 L of total water a day for women and 2.5 L for men in Europe, or 2.7 L and 3.7 L in the US. Both are adequate intakes, set from what healthy, well-hydrated people take in, not a minimum. Total water means drinks plus the water in food.

NASEM says about 80% of it comes from drinks, and gives drinks of about 2.2 L for women and 3.0 L for men. EFSA does not split its figure, so the drinks column below applies NASEM's 80% to it.

EFSA applies the adult figures from age 14 and keeps them the same for older adults. Older adults need less energy, which on its own would lower a water figure built partly on calories eaten, but EFSA notes that their kidneys concentrate urine less well, so they need more water for each calorie, and EFSA keeps the total the same.

NASEM keeps its figures the same after 50 and after 70. EFSA's figures assume a moderate climate and moderate activity, and it notes that losses in extreme heat and exercise can reach about 8 litres a day. EFSA also built its figures partly from water per calorie eaten, so if your energy needs are far from average, the calorie calculator shows where you sit.

How much water do children and teens need a day?

From about 1.1 to 1.2 L a day at age 1 to adult levels in the mid teens. EFSA sets 1.6 L at 4 to 8 years and treats teenagers from 14 as adults.

The US National Academies set 1.7 L at 4 to 8, of which about 1.2 L comes from drinks, and keep separate teen figures to 18. Like the adult figures, these are total water from drinks and food, for healthy children in a moderate climate.

The calculator above is for adults, because the sweat rates and the 2% guide it uses come from studies of adults. For children, the NHS says the best drinks are water and milk, and that sugary fizzy drinks, squash and juice drinks are best avoided. Singapore's heat stress advisory lists children among those to take greater care in the heat.

How many glasses of water a day does HPB recommend?

6 to 8 glasses a day. HealthHub's article from the Health Promotion Board calls this "the recommended 6 to 8 glasses of water per day". It does not give a glass size.

At 250 ml a glass that is 1.5 to 2.0 L, which sits close to the drinks share of EFSA's 2.0 L for women (1.6 L) and below NASEM's 3.0 L for men. HealthHub adds that breastfeeding mothers should drink more.

Do tea, coffee and milk count towards your water intake?

Yes. EFSA counts "beverages of all kind" in total water, and NASEM names juices and milk alongside drinking water. On caffeine, NASEM's water chapter found the evidence inconsistent: higher doses, above 180 mg a day, have been shown to raise urine output, perhaps only for a while, but it concludes that caffeinated drinks appear to add to daily water about as much as other drinks. The NHS says water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count.

1. 01Kopi and teh count,But added sugar adds calories. HealthHub makes the same point about most drinks other than plain water.
2. 02Milk counts,And the NHS suggests lower-fat milk for adults.
3. 03Food counts tooNASEM puts food at about 20% of total water, which is why the drinks figure here is below the total.
4. 04When you are already dehydrated,For example after being sick, the NHS advises avoiding caffeinated drinks and alcohol and starting with small sips.

How do you know if you are drinking enough?

Pale yellow urine and little thirst are the everyday signs. The NHS suggests drinking enough that your pee is a clear pale yellow. Its dehydration page lists these signs that you are not:

• Feeling thirsty
• Dark yellow, strong-smelling pee, or peeing less often than usual
• Headache, or feeling dizzy or light-headed
• Feeling tired
• A dry mouth, lips and tongue
• Sunken eyes

These are rough guides, not measurements. NASEM found no precise link between urine colour and hydration, and notes that people tend to under-replace fluid in the short term even when they drink freely.

EFSA says a loss of about 1% of body weight in water is normally made up within 24 hours. For exercise, the weigh-in below is the better check. The NHS advises seeing a doctor urgently for unusual tiredness, dizziness on standing that does not go away, or fast breathing or a fast heartbeat.

Which foods have the most water?

Fruit and vegetables, many above 85% water. In NASEM's table of water content, drawn from US Department of Agriculture data, iceberg lettuce is 96% water by weight, cantaloupe 90%, oranges 87% and apples 86%, while white bread is 36% and walnuts 4%.

NASEM says fruit and vegetables contain a high percentage of water. Food supplies about 20% of total water in its surveys, so a plate heavy on fruit and vegetables carries more of it.

Does daily water intake depend on body weight?

Not in the official figures. Neither EFSA nor NASEM sets an adult's daily water by kilograms, and we found no official source for a "ml per kg" rule, so this calculator does not use one.

Your weight matters for exercise instead: it sets the most you should lose in one session. ACSM advises drinking enough to avoid losing more than 2% of body weight, which is 1.3 kg for a 65 kg person.

How much more water do you need when you exercise?

The amount you sweat, which for runners is about 0.7 to 1.1 litres an hour and can pass 2.0 litres in the heat.

NASEM's water chapter reports about 0.7 L an hour for women and 1.0 L for men running in temperate weather, about 1.1 L for women runners in warm weather, and 1.0 to 2.0 L or more for men training or racing in the heat. These are runners' figures, so a weigh-in tells you more for other sessions. Read across for your session length.

Replace most of it over the rest of the day, on top of your usual drinks. ACSM says sweat rates vary so much between people that a plan should be your own, which is why the calculator takes your measured rate if you have one.

How do you work out your sweat rate?

Weigh yourself before and after a session. ACSM estimates sweat rate from the change in body weight, and each kilogram lost is roughly a litre of fluid, as sweat is mostly water. Add back what you drank during the session, then divide by the hours.

1. 01Weigh beforeAfter the toilet, in light clothes. Say 65 kg.
2. 02Train for a set timeAnd note what you drink. Say 60 minutes and 0.5 L.
3. 03Weigh after,Towelled dry, in the same clothes. Say 64.2 kg, a loss of 0.8 kg, or 1.2% of your weight.
4. 04Sweat rateThe loss plus the drink, per hour. 0.8 plus 0.5 is about 1.3 L an hour. Enter it in the calculator.

Repeat it in the conditions you usually train in, as heat changes the answer. If you time your runs over a fixed distance, the running pace calculator keeps the effort comparable from one weigh-in to the next. If you weigh more after a session than before, you drank more than you sweated.

How much water does a 65 kg woman need after 45 minutes in the heat?

About 2.4 to 3.0 L of drinks that day, or 10 to 12 glasses of 250 ml. Here is how the calculator gets there for a 65 kg woman who trains for 45 minutes outdoors in Singapore's heat.

1. 01BaselineTotal water of 2.0 L (EFSA) to 2.7 L (NASEM). Drinks give about 80%, so 1.6 to 2.2 L, or 7 to 9 glasses. Her weight does not change this.
2. 02Sweat1.1 L an hour, NASEM's figure for women runners in warm weather, for 45 minutes is about 0.8 L (4 glasses).
3. 03The 2% line2% of 65 kg is 1.3 kg. Losing 0.825 L before rounding is about 1.3% of her weight, under the line, so she needs no set amount during the session and replaces it afterwards.
4. 04The day1.6 to 2.2 L plus 0.8 L is 2.4 to 3.0 L of drinks.

The same session in an air-conditioned gym, at 0.7 L an hour, adds about 0.5 L instead, for 2.1 to 2.7 L that day. Her own weigh-in beats both figures.

How much water do you need in Singapore's heat?

More than the baseline, by whatever you sweat, and the official heat advice is to drink more fluids once heat stress is moderate or high. Singapore's heat stress advisory from the Meteorological Service and NEA uses the Wet Bulb Globe Temperature (WBGT), which counts air temperature, humidity, wind and sun together. The government's launch release notes that 2013 to 2022 was Singapore's warmest decade on record.

The advisory asks the elderly, children, pregnant women, people who are ill or have chronic conditions, and people just back from cooler climates to take greater care.

Our coaches run sessions at homes, condo gyms and parks, and our plans put outdoor runs early or late: the 2.4km training plan runs before 8am or after 7pm. That is our coaching approach, not an official rule. Check the WBGT reading on the myENV app before an outdoor session.

How can you increase your water intake?

Tie drinks to things you already do, such as meals and training. NASEM says thirst and drinks at meals keep most healthy people hydrated day to day. The habits below are how our coaches help clients drink more, not official rules.

1. 01A glass of water with every meal,So the habit has a cue.
2. 02A bottle you can measure,So you know how many refills make your number.
3. 03Drink before you train,Then sip during and replace the rest after, using your weigh-in.
4. 04Plain water firstHealthHub points out that most other drinks add sugar and calories.

For pregnancy and breastfeeding, EFSA and NASEM both raise the figure, and the calculator adds it. The trimester exercise guide covers training in the heat while pregnant.

Can you drink too much water?

Yes, though it is rare in healthy people. EFSA says drinking more than the kidney can clear, at most about 0.7 to 1.0 litres an hour, can cause hyponatraemia (water intoxication) with swelling of the brain.

NASEM notes that hyponatraemia during exercise is typically linked to more than 6 hours of prolonged stressful exercise, and can come from drinking too much, replacing too little sodium, or both. In a long event, drink to replace what you sweat, not more. A weigh-in that shows a gain means you overdid it.

Who should not rely on this calculator?

1. 01Anyone told to limit fluidsHeart failure care includes fluid and salt restriction, according to Tan Tock Seng Hospital, and people with kidney disease and swelling may be advised to cut fluid, according to the NHS. Follow your doctor's figure, not this one.
2. 02Older adultsNASEM reports that thirst and fluid intake are impaired in the elderly, so waiting to feel thirsty can fall short. Drinking at set times helps.
3. 03Long events and heavy sweatersEFSA says large sweat losses need their electrolytes replaced as well as the water. Use a weigh-in, and get advice for events of many hours.
4. 04Pregnancy and breastfeedingThe calculator adds the official amounts, but your obstetrician's advice comes first.
5. 05Urine colour as a checkThe NHS suggests aiming for clear, pale yellow urine, but NASEM found no precise link between urine colour and hydration. Treat it as a rough sign, not a measurement.