BMI 计算器 — 按年龄和性别计算体质指数
本 BMI 计算器根据身高和体重计算您的体质指数，并结合年龄和性别提供个性化解读。查看您的 BMI 分类、健康体重范围，了解您的数值意味着什么。BMI 是筛查工具，并非医疗诊断——请咨询医疗专业人员获取个性化建议。
Body Mass Index Calculator
Enter your height and weight to calculate your BMI and see which category you fall into.
Frequently Asked Questions
健康的 BMI 是多少？
世界卫生组织（WHO）将 18.5 至 24.9 的 BMI 范围定义为「正常体重」。低于 18.5 为体重不足，25.0-29.9 为超重，30.0 及以上为肥胖。但 BMI 是筛查工具，并非医学诊断，请咨询医疗专业人员进行个性化健康评估。
如何计算我的 BMI？
BMI = 体重（kg）/ 身高（m）²。英制单位：BMI = 体重（磅）× 703 / 身高（英寸）²。例如，体重 70 kg、身高 1.75 m 的人：BMI = 70 / (1.75)² = 22.9，属于正常体重范围。
BMI 公式是什么？
公制公式：BMI = kg/m²。英制公式：BMI = (磅 × 703) / 英寸²。两者结果相同。例如：150 磅，身高 5'7"（67 英寸）= (150 × 703) / (67 × 67) = 105,450 / 4,489 = 23.5 BMI。
BMI 多少算超重？
WHO 将 25.0 至 29.9 的 BMI 定义为超重。对于亚裔人群，WHO 建议采用更低的阈值：23.0-27.4 为超重，27.5 及以上为肥胖，因为这些人群在较低 BMI 时健康风险更高。
BMI 多少算肥胖？
BMI 30.0 及以上为肥胖，分为三个等级：I 级（30.0-34.9）、II 级（35.0-39.9）和 III 级即重度肥胖（40.0 及以上）。等级越高，患 2 型糖尿病、心脏病和某些癌症等疾病的风险越大。
BMI 能准确衡量健康状况吗？
BMI 是有用的筛查工具，但存在局限性。它无法区分肌肉与脂肪、骨密度或脂肪分布。运动员可能在体脂率较低的情况下 BMI 偏高。老年人可能在肌肉流失的情况下 BMI 看起来正常。全面评估应将 BMI 与腰围、体脂率和临床检查结合使用。
女性的正常 BMI 是多少？
18.5-24.9 的健康 BMI 范围适用于男女两性。但女性在相同 BMI 下自然携带比男性更多的体脂。女性 BMI 22 约对应 25-28% 的体脂率，而男性相同 BMI 约对应 18-22% 的体脂率。
男性的正常 BMI 是多少？
男性同样适用 18.5-24.9 的范围。但肌肉量较大的男性（运动员、健身爱好者）BMI 可能在超重范围（25-29.9），身体却完全健康。对于肌肉发达的男性，腰围（低于 40 英寸/102 cm）是更好的健康指标。
BMI 会随年龄变化吗？
所有成年人使用相同的 BMI 公式，但身体成分会随年龄变化。老年人往往会失去肌肉量并增加脂肪，因此「正常」BMI 仍可能表明体脂偏高。部分研究者认为，对 65 岁以上成年人而言，略高的 BMI 范围（23-28）可能与更低的死亡率相关。
儿童和青少年的 BMI 有何不同？
对于 2-19 岁人群，BMI 的计算方式相同，但需通过 CDC 按年龄和性别划分的生长曲线以百分位数解读。低于第 5 百分位为体重不足，第 5-85 百分位为健康体重，第 85-95 百分位为超重，第 95 百分位及以上为肥胖。这考虑了生长期间自然的身体成分变化。
什么是 BMI 素数？
BMI 素数是你的 BMI 除以 25（正常体重上限）。BMI 素数 1.0 表示你处于正常体重的上边界。低于 1.0 为体重不足或正常；高于 1.0 为超重。例如，BMI 27.5 的 BMI 素数为 1.10，意味着你超过正常体重上限 10%。
BMI 考虑肌肉量吗？
不，BMI 不区分肌肉、脂肪、骨骼或水分重量，这是其最大局限。一个 200 磅、身高 6 英尺的人 BMI 为 27.1，无论这些重量主要来自肌肉还是脂肪。对于运动员和体力活跃的人，体脂率或 DEXA 扫描是更准确的身体成分测量方法。
How to Calculate Your Body Mass Index (BMI)
What is BMI?
Body Mass Index (BMI) is a widely used screening measure that estimates body fat based on a person's height and weight. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s and remains one of the most common tools used by healthcare professionals to assess whether an individual is at a healthy weight.
BMI provides a simple numeric value that places individuals into categories ranging from underweight to obese. While it does not directly measure body fat percentage, it serves as a useful starting point for health assessments and population-level studies.
How to Use This Calculator
- Select your preferred unit system: Imperial (feet, inches, pounds) or Metric (centimeters, kilograms).
- Enter your height using the appropriate fields.
- Enter your weight.
- Click "Calculate BMI" to see your result, category, and where you fall on the BMI scale.
- Use the copy button to save your results for future reference.
BMI Formula
The BMI formula divides weight by the square of height:
BMI = weight (kg) / height (m)²
For imperial units, the conversion is:
- Weight in kg = weight in lbs × 0.453592
- Height in meters = (feet × 12 + inches) × 0.0254
BMI Categories
The World Health Organization (WHO) defines the following BMI categories for adults:
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II | 35.0 – 39.9 |
| Obese Class III | ≥ 40.0 |
Examples
Example 1: Metric Calculation
A person who is 175 cm tall and weighs 70 kg:
BMI = 70 / (1.75)² = 70 / 3.0625 = 22.9 (Normal weight)
Example 2: Imperial Calculation
A person who is 5'10" (70 inches) and weighs 180 lbs:
Height in meters = 70 × 0.0254 = 1.778 m
Weight in kg = 180 × 0.453592 = 81.6 kg
BMI = 81.6 / (1.778)² = 81.6 / 3.161 = 25.8 (Overweight)
Use Cases
- Health Screening: Quickly assess whether your weight is within a healthy range during routine health checkups.
- Fitness Goals: Track your BMI over time as part of a weight management or fitness program.
- Population Studies: Researchers use BMI to study obesity trends and health outcomes across large groups.
- Insurance Assessments: Some insurers use BMI as one factor when evaluating health risk profiles.
- Clinical Reference: Healthcare providers use BMI alongside other metrics to evaluate overall health.
Tips and Limitations
While BMI is a useful screening tool, it has important limitations to keep in mind:
- BMI does not distinguish between muscle mass and fat mass. Athletes with high muscle mass may have a high BMI despite being lean.
- Age, gender, and ethnicity can influence the relationship between BMI and body fat.
- BMI is not recommended as the sole diagnostic tool for determining health status.
- For a more complete picture, consider combining BMI with waist circumference, body fat percentage, and other health indicators.
- Consult a healthcare professional for personalized health advice based on your individual circumstances.
BMI categories are designed for adults aged 20 and older. For children and teenagers, BMI is interpreted differently using age-specific and sex-specific percentile charts.
BMI Categories Reference Table
| Category | BMI Range | Asian BMI Range | Health Risk |
|---|---|---|---|
| Severe Thinness | < 16.0 | < 16.0 | Severe |
| Moderate Thinness | 16.0 - 16.9 | 16.0 - 16.9 | Moderate |
| Mild Thinness | 17.0 - 18.4 | 17.0 - 18.4 | Low |
| Normal Weight | 18.5 - 24.9 | 18.5 - 22.9 | Minimal |
| Overweight | 25.0 - 29.9 | 23.0 - 27.4 | Increased |
| Obese Class I | 30.0 - 34.9 | 27.5 - 32.4 | High |
| Obese Class II | 35.0 - 39.9 | 32.5 - 37.4 | Very High |
| Obese Class III | ≥ 40.0 | ≥ 37.5 | Extremely High |
Asian BMI thresholds are recommended by WHO for populations of South Asian, Chinese, and Japanese descent due to higher health risks at lower BMI values.
Healthy Weight Range by Height
The following table shows the healthy weight range (BMI 18.5-24.9) for common heights.
| Height | Min Weight (BMI 18.5) | Max Weight (BMI 24.9) |
|---|---|---|
| 5'0" (152 cm) | 95 lbs (43 kg) | 128 lbs (58 kg) |
| 5'2" (157 cm) | 101 lbs (46 kg) | 136 lbs (62 kg) |
| 5'4" (163 cm) | 108 lbs (49 kg) | 145 lbs (66 kg) |
| 5'6" (168 cm) | 115 lbs (52 kg) | 154 lbs (70 kg) |
| 5'8" (173 cm) | 122 lbs (55 kg) | 164 lbs (74 kg) |
| 5'10" (178 cm) | 129 lbs (59 kg) | 174 lbs (79 kg) |
| 6'0" (183 cm) | 136 lbs (62 kg) | 184 lbs (83 kg) |
| 6'2" (188 cm) | 144 lbs (65 kg) | 194 lbs (88 kg) |
| 6'4" (193 cm) | 152 lbs (69 kg) | 204 lbs (93 kg) |
Important Health Disclaimer
This calculator is for informational purposes only.
- BMI is a screening tool, not a medical diagnosis.
- It does not distinguish between muscle mass, bone density, and body fat.
- BMI may not accurately reflect health for athletes, elderly, pregnant women, or certain ethnic groups.
- Consult your healthcare provider for personalized health assessments and medical advice.
Data sources: World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH).
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