BMI 计算器

输入身高和体重，快速评估你的身体质量指数

你的 BMI 指数
--
--
--

BMI 参考标准（中国）

分类 BMI 范围 健康风险
体重过低 < 18.5 营养不良风险
正常体重 18.5 - 23.9 健康范围
超重 24.0 - 27.9 慢性病风险增加
肥胖 ≥ 28.0 慢性病高风险

BMI 是什么？

BMI（Body Mass Index，身体质量指数）是国际上常用的衡量人体胖瘦程度以及是否健康的一个标准。它通过身高和体重的比例关系，给出一个简单的数值，帮助人们快速了解自己的体重状况。

BMI 的计算公式非常简单：

BMI = 体重(kg) ÷ 身高(m)²

例如，一个人身高 175cm，体重 70kg，那么他的 BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9，属于正常范围。

BMI 正常范围是多少？

需要注意的是，不同地区采用的 BMI 标准有所不同：

  • 世界卫生组织（WHO）标准：正常范围为 18.5 - 24.9
  • 中国标准：正常范围为 18.5 - 23.9（亚洲人骨架较小，标准更严格）
  • 日本标准：正常范围为 18.5 - 22.9

本计算器采用中国卫生行业标准（WS/T 428-2013），更适合中国人体质。

BMI 的局限性

虽然 BMI 是一个方便快捷的评估工具，但它也有明显的局限性：

  1. 不区分肌肉和脂肪：运动员肌肉量大，BMI 可能显示"超重"，但实际上体脂率很低。
  2. 不反映脂肪分布：腹部脂肪（内脏脂肪）比皮下脂肪危害更大，但 BMI 无法区分。
  3. 不适用于特殊人群：孕妇、儿童、老年人需要采用不同的评估标准。
  4. 种族差异：同样的 BMI，亚洲人患糖尿病的风险高于欧洲人。

因此，BMI 应作为初步筛查工具，而非诊断标准。如有健康疑虑，建议咨询专业医生。

如何维持健康 BMI？

如果你的 BMI 不在正常范围内，可以通过以下方式调整：

  • 饮食控制：减少精制碳水摄入，增加蔬菜和优质蛋白质比例。
  • 规律运动：每周至少 150 分钟中等强度有氧运动（如快走、游泳）。
  • 充足睡眠：每天 7-8 小时睡眠有助于调节新陈代谢。
  • 减少久坐：每小时起身活动 5 分钟，避免长时间静坐。

常见问题

BMI 和体脂率有什么区别？

BMI 只考虑身高和体重，而体脂率直接测量体内脂肪占比。体脂率更能反映真实的肥胖程度，但需要专业设备测量。

儿童的 BMI 怎么算？

儿童需要使用年龄和性别对应的 BMI 百分位数，而非成人标准。建议使用专门的儿童 BMI 计算器。

BMI 正常但肚子大怎么办？

这可能是"隐性肥胖"或内脏脂肪过多。建议测量腰围（男性 ≥90cm、女性 ≥85cm 为腹型肥胖），并增加核心训练。

为什么早上和晚上体重差很多？

一天内体重波动 1-2kg 是正常的，受饮食、水分、排泄等因素影响。建议固定时间（如早晨空腹）测量。

BMI Calculator

Enter your height and weight to quickly assess your Body Mass Index

Your BMI
--
--
--

BMI Reference (WHO Standard)

Category BMI Range Health Risk
Underweight < 18.5 Malnutrition risk
Normal 18.5 - 24.9 Healthy range
Overweight 25.0 - 29.9 Increased disease risk
Obese ≥ 30.0 High disease risk

What is BMI?

BMI (Body Mass Index) is an internationally used standard to measure body fatness and assess health status. It provides a simple numerical value based on the ratio of height to weight, helping people quickly understand their weight condition.

The BMI formula is straightforward:

BMI = weight(kg) ÷ height(m)²

For example, a person who is 175cm tall and weighs 70kg has a BMI of 70 ÷ (1.75 × 1.75) ≈ 22.9, which falls within the normal range.

What is a Healthy BMI?

It's important to note that BMI standards vary by region:

  • WHO Standard: Normal range is 18.5 - 24.9
  • Asian Standard (China): Normal range is 18.5 - 23.9 (stricter due to smaller frame size)
  • Japan Standard: Normal range is 18.5 - 22.9

This calculator uses the WHO international standard. For Asian users, please refer to the Chinese version which applies local standards.

Limitations of BMI

While BMI is a convenient screening tool, it has significant limitations:

  1. Does not distinguish muscle from fat: Athletes may have a high BMI due to muscle mass while having low body fat.
  2. Does not reflect fat distribution: Abdominal fat (visceral fat) is more dangerous than subcutaneous fat, but BMI cannot differentiate.
  3. Not suitable for special populations: Pregnant women, children, and elderly require different assessment criteria.
  4. Ethnic differences: At the same BMI, Asians have higher diabetes risk compared to Europeans.

Therefore, BMI should be used as a preliminary screening tool, not a diagnostic standard. Consult a healthcare professional for personalized advice.

How to Maintain a Healthy BMI?

If your BMI falls outside the normal range, consider these adjustments:

  • Diet control: Reduce refined carbohydrates, increase vegetables and quality protein.
  • Regular exercise: At least 150 minutes of moderate-intensity aerobic activity per week (e.g., brisk walking, swimming).
  • Adequate sleep: 7-8 hours daily helps regulate metabolism.
  • Reduce sedentary time: Stand up and move for 5 minutes every hour.

Frequently Asked Questions

What's the difference between BMI and body fat percentage?

BMI only considers height and weight, while body fat percentage directly measures fat proportion. Body fat percentage better reflects true obesity but requires professional equipment.

How is BMI calculated for children?

Children require age and gender-specific BMI percentiles rather than adult standards. Use a dedicated children's BMI calculator for accurate assessment.

My BMI is normal but I have a big belly. What should I do?

This may indicate "hidden obesity" or excess visceral fat. Measure your waist circumference (≥90cm for men, ≥85cm for women indicates abdominal obesity) and increase core exercises.

Why does my weight fluctuate throughout the day?

Daily weight fluctuations of 1-2kg are normal due to food intake, hydration, and elimination. Weigh yourself at consistent times (e.g., morning on an empty stomach) for accuracy.