# Water intake calculator

> Daily water intake in litres, glasses and fl oz from body weight, exercise and climate, compared with EFSA and US adequate intakes.

交互版本：https://www.calcopenly.com/zh/health/water-intake-calculator
主题：健康与健身计算器

The estimate adds three parts: a baseline of 35 mL per kg of body weight (30 mL/kg is often used for adults over 65), 0.6 L for each hour of exercise, which is the midpoint of the American College of Sports Medicine's 0.4–0.8 L per hour, and 0.5 or 1.0 L for a warm or hot climate. The total is shown in litres, 250 mL glasses and US fluid ounces.

People use it to set a daily drinking goal. A 70 kg adult who exercises for 30 minutes in a temperate climate gets 2.45 + 0.3 = 2.75 L, about 11 glasses. The European Food Safety Authority's adequate intake is 2.5 L for men and 2.0 L for women, and the US National Academies' is 3.7 L and 2.7 L; both count water from food as well as drinks.

These are population figures for healthy adults. Sweat rates vary widely, and heart failure, kidney disease and some medicines call for a fluid limit set by a clinician.

## 输入

- **Weight**
- **Exercise per day**
- **Climate** (选项：Temperate, Warm, Hot (around 32 °C))
- **Sex (for the reference intakes)**: Only changes the EFSA and US comparison bars, not the estimate. (选项：Male, Female)
- **Baseline per kilogram**: 30–35 mL/kg/day is the usual clinical estimate; 30 is typical for adults over about 65.

## 结果

- Daily fluid (L/day) — 主要结果
- Glasses of 250 mL
- 美制液量盎司 (fl oz/day)
- From body weight (L)
- For exercise (L)
- For climate (L)

## 公式

$$
V = \frac{w \times k}{1000} + 0.6 \times \frac{t_{\text{exercise}}}{60} + V_{\text{climate}}\quad(\text{L/day})
$$

## 计算示例

### 70 kg, 30 min exercise, temperate

- Weight: 70 kg
- Exercise per day: 30 min
- Climate: Temperate
- Sex (for the reference intakes): Male
- **Daily fluid: 2.75 L/day**
- **Glasses of 250 mL: 11**
- **From body weight: 2.45 L**
- **For exercise: 0.30 L**
- 核验来源：Python 3.8 decimal: 70 × 35 / 1000 + 0.6 × 30/60 = 2.75 L; 2.75 / 0.25 = 11 glasses

### 180 lb, 60 min, hot climate

- Weight: 180 lb
- Exercise per day: 60 min
- Climate: Hot (around 32 °C)
- Sex (for the reference intakes): Male
- **Daily fluid: 4.46 L/day**
- **美制液量盎司: 151 fl oz/day**
- 核验来源：Python 3.8 decimal: 180 × 0.45359237 × 35 / 1000 + 0.6 + 1.0 = 4.457632 L = 150.73 US fl oz

### Edge: no exercise, 30 mL/kg, 60 kg

- Weight: 60 kg
- Exercise per day: 0 min
- Climate: Temperate
- Sex (for the reference intakes): Male
- Baseline per kilogram: 30 mL/kg
- **Daily fluid: 1.80 L/day**
- **For exercise: 0.00 L**
- **For climate: 0.00 L**
- **Glasses of 250 mL: 8**
- 核验来源：Python 3.8 decimal: 60 × 30 / 1000 = 1.8 L; 1.8 / 0.25 = 7.2, rounded up to 8

### 55 kg, 90 min, warm climate

- Weight: 55 kg
- Exercise per day: 90 min
- Climate: Warm
- Sex (for the reference intakes): Male
- **Daily fluid: 3.32 L/day**
- 核验来源：Python 3.8 decimal: 55 × 35 / 1000 + 0.6 × 1.5 + 0.5 = 3.325 L

## 常见问题

### How much water should you drink a day?

Reference values count total water from drinks and food. EFSA sets adequate intakes of 2.5 L a day for men and 2.0 L for women; the US National Academies set 3.7 L and 2.7 L, of which about 3.0 L and 2.2 L typically come from drinks. These are population averages for healthy adults in temperate conditions, and needs rise with heat, exercise, pregnancy and breastfeeding.

### Is the 8 glasses of water a day rule true?

It is a rule of thumb, not a guideline. Eight 8 oz glasses make 1.9 L, and a 2002 review by Heinz Valtin in the American Journal of Physiology found no scientific evidence behind the rule. The figure falls between EFSA's adequate intakes of total water for women (2.0 L) and men (2.5 L), which already include the 20–30 % that usually comes from food.

### How much water should you drink during exercise?

The American College of Sports Medicine's 2007 position stand gives about 0.4 to 0.8 L per hour as a starting point, adjusted to sweat rate, with the aim of keeping body weight loss under 2 %. Weighing before and after a session shows the loss: each kilogram lost is about 1 litre of sweat. Drinking well beyond sweat losses risks exercise-associated hyponatraemia.

### Do coffee and tea count toward water intake?

Yes. The US National Academies' 2005 reference intakes for water concluded that caffeinated drinks contribute to total water intake much as non-caffeinated drinks do, because moderate caffeine does not cause a net loss of body water over the day. Food counts too: it supplies about 20 % of total water intake in the US diet.

### “Water intake calculator”有多准确？

准确性取决于输入值和方法的假设。十进制运算使用50位有效数字，但估算、数值方法和源数据的精度可能较低；显示时的舍入并不能消除这些限制。 已按独立来源核验的计算示例：4。 例如，“70 kg, 30 min exercise, temperate”根据Python 3.8 decimal: 70 × 35 / 1000 + 0.6 × 30/60 = 2.75 L; 2.75 / 0.25 = 11 glasses进行核验。

### 这种方法出自哪里？

Masot O. et al. Fluid intake recommendation considering the physiological adaptations of adults over 65 years: a critical review. Nutrients 2020;12(11):3383 (30 mL/kg/day standard); American College of Sports Medicine. Exercise and fluid replacement (position stand). Med Sci Sports Exerc 2007;39(2):377–390; Howard G, Bartram J. Domestic water quantity, service level and health. WHO/SDE/WSH/03.02 (2003), Table 1 (IPCS 1994 reference intakes); EFSA Panel on Dietetic Products. Scientific opinion on dietary reference values for water. EFSA Journal 2010;8(3):1459; Institute of Medicine. Dietary Reference Intakes for water, potassium, sodium, chloride, and sulfate. National Academies Press, 2005 (AI 3.7 L men, 2.7 L women).

## 来源

- [Masot O. et al. Fluid intake recommendation considering the physiological adaptations of adults over 65 years: a critical review. Nutrients 2020;12(11):3383 (30 mL/kg/day standard)](https://pmc.ncbi.nlm.nih.gov/articles/PMC7694182/)
- [American College of Sports Medicine. Exercise and fluid replacement (position stand). Med Sci Sports Exerc 2007;39(2):377–390](https://pubmed.ncbi.nlm.nih.gov/17277604/)
- [Howard G, Bartram J. Domestic water quantity, service level and health. WHO/SDE/WSH/03.02 (2003), Table 1 (IPCS 1994 reference intakes)](https://iris.who.int/handle/10665/67884)
- [EFSA Panel on Dietetic Products. Scientific opinion on dietary reference values for water. EFSA Journal 2010;8(3):1459](https://doi.org/10.2903/j.efsa.2010.1459)
- [Institute of Medicine. Dietary Reference Intakes for water, potassium, sodium, chloride, and sulfate. National Academies Press, 2005 (AI 3.7 L men, 2.7 L women)](https://doi.org/10.17226/10925)

_仅供参考，不构成医疗建议。这些公式描述的是人群，并非您的个人情况；根据结果采取行动前，请咨询医务人员。_