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Water Intake Calculator

Hydration is essential for body function. How much water you need depends on your weight, activity level, climate and health. This calculator computes your daily water intake based on scientific research.

kg

結果

2,310 ml

Daily water (ml)

Daily water (liters)
2.31 L
Cups per day (8oz)
9.6 kopjes
How this was calculated
  1. 1Calculate base water intake70 kg × 33 ml/kg = 2,310 ml
  2. 2Adjust for activity level2,310 ml × 1 = 2,310 ml

公式

Daily water = Body weight (kg) × 33 ml/kg × Activity multiplier. The 33 ml/kg rule is the basic recommendation from the "Adequate Intake" standard.

Base water intake is approximately 33 ml per kg of body weight. This is increased based on your activity level (sedentary = no increase, very active = 2× increase). People who exercise more or live in warmer climates need more water.

ステップ解説

  1. 1Enter your body weight in kilograms.
  2. 2Select your activity level (sedentary to very active).
  3. 3The calculator computes your daily water intake in milliliters and liters.
  4. 4Spread your water intake over the day — drink regularly in small amounts.

計算例

Adult 70 kg, sedentary

70 × 33 × 1.0 = 2,310 ml = 2.3 L ≈ 9 cups per day

Athlete 80 kg, very active

80 × 33 × 2.0 = 5,280 ml = 5.3 L ≈ 22 cups per day

Child 40 kg, lightly active

40 × 33 × 1.2 = 1,584 ml = 1.6 L ≈ 7 cups per day

Reference table

Activity multipliers and guidelines
Activity levelMultiplierDescription
Sedentary1.0No regular exercise
Lightly active1.21-3 days per week light exercise
Moderately active1.53-5 days per week moderate exercise
Very active2.06-7 days per week intense exercise

Adjust the multiplier to your lifestyle and climate — hot weather increases water needs.

よくある間違い

  • Counting all liquids equally — caffeine, alcohol and salt affect water loss and need.
  • Ignoring water from food — fruits and vegetables contain 70-95% water.
  • Not adjusting for climate — hot/humid weather increases water needs; dry weather increases evaporation.

活用シーン

  • Health and fitness tracking — ensure proper hydration for optimal performance.
  • Daily planning — spread your water intake over the day for consistent levels.
  • Health and wellness programs — guiding clients on proper hydration.

よくある質問

Is 8 glasses a day always enough?

No, the "8x8" rule (8 glasses of 8oz per day) is an approximation. Your actual need depends on weight, activity and climate. This calculator provides a more personalized estimate.

How much water is too much?

Water intoxication (hyponatremia) is rare but can occur with extremely high intake (>3 liters per hour). For most people, more water is not a problem — your kidneys regulate what's needed. Drinking to thirst is usually a good guide.

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