Water Intake Calculator

Weight

Activity level (1=low, 2=moderate, 3=high)

🇩🇰 All calculations are based on Danish rules, rates, and currency (DKK). This calculator is translated for convenience but applies exclusively to Denmark.

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The general daily fluid need for an adult is approximately 1.5-2 litres. A rule of thumb is to drink 1/3 decilitre of water per kilogram of body weight (e.g. 75 kg = 25 dl / 2.5 litres). The need increases with physical activity, heat, or illness, where extra fluid is necessary.

Basic need: 1.5-2 litres daily for healthy adults. Weight-based: Body weight (kg) x 0.033 = litres of water per day (e.g. 70 kg x 0.033 ≈ 2.3 litres). Activity/Heat: During exercise or in warm environments, intake should increase, often up to 2-4 litres daily. Age: Older adults should pay special attention to drinking enough, as the sensation of thirst diminishes.

All fluids count: Water, coffee, tea, and juice all count toward the total. Drink when thirsty: The body usually sends signals when it needs fluid. Too much water: It is rare, but you can drink too much, so follow your body's needs.

Note: These are general guidelines. Personal needs may vary based on health conditions.

Water Intake Calculator

Staying properly hydrated is essential for nearly every bodily function, including temperature regulation, joint lubrication, nutrient transport, and cognitive performance. This calculator estimates your daily water needs based on your body weight and how physically active you are throughout the day.

How Much Water Do You Need?

A common guideline is approximately 30 ml of water per kilogram of body weight per day for low activity, 35 ml for moderate activity, and 40 ml for high activity levels. These figures include water from all sources — drinks and food. In Denmark's temperate climate, you may need less than in hot climates, but indoor heating during winter can increase your needs.

Signs of Dehydration

Thirst is not always a reliable indicator of hydration status, especially as you age. Other signs of mild dehydration include dark yellow urine, headaches, fatigue, and difficulty concentrating. Aim to drink water consistently throughout the day rather than consuming large amounts at once. Carry a reusable water bottle to make it easier to stay on track.

Frequently Asked Questions

How much fluid does a 70 kg person need?

For a 70 kg person, it corresponds to approximately 1700 ml of urine per day. Metabolic fluid (combustion water) is produced through the metabolism of energy-providing nutrients, also known as oxidation water.

How much should you urinate relative to fluid intake?

A normal urination consists of 250-400 ml of urine. The total urine volume per day should not exceed 2 litres. If you drink more than 1.5-2 litres of fluid, you may need to use the bathroom more often. One urination during the night is considered normal.

Can you drink too much water?

Yes, although it is rare, you can drink too much water. The condition is called hyponatraemia and occurs when blood sodium becomes too diluted. It typically only happens with extremely high water intake over a short period. For most people, it is more important to drink enough than to worry about drinking too much. Follow your body's signals and drink when thirsty.

Water Intake Calculator

Water Intake Calculator

How Much Water Do You Need?

Signs of Dehydration

Frequently Asked Questions

Sources