A number on the scale doesn't tell the full story. Someone who is 5'3" and 132 lbs is in a completely different situation than someone who is 5'11" and 132 lbs.
BMI (Body Mass Index) gives you a single number that puts your weight in context with your height, so you can quickly see where you stand.
Key Takeaway
BMI = Weight (kg) ÷ Height (m)²
18.5 to 24.9 is the normal range
What Is BMI?
BMI stands for Body Mass Index. It uses your height and weight to estimate whether you're underweight, normal, overweight, or obese. It's the most widely used screening tool by healthcare providers worldwide.
📏 What You Need
Just two things: your height and your weight.
🔢 What You Get
A single number that tells you whether you're underweight, normal, overweight, or obese.
How to Calculate BMI
The formula is simple:
BMI = Weight (kg) ÷ (Height (m) × Height (m))
Example: Height 5'7" (170 cm), Weight 150 lbs (68 kg)
BMI = 68 ÷ (1.70 × 1.70) = 68 ÷ 2.89 = 23.5
💡 If using imperial units: BMI = (Weight in lbs × 703) ÷ (Height in inches)²
BMI Categories (WHO Standard)
| BMI Range | Category | Health Risk |
|---|---|---|
| Under 18.5 | Underweight | Nutritional deficiency risk |
| 18.5 – 24.9 | Normal | Low |
| 25.0 – 29.9 | Overweight | Increased |
| 30.0 – 34.9 | Obesity Class I | High |
| 35.0 – 39.9 | Obesity Class II | Very high |
| 40.0 and above | Obesity Class III | Extremely high |
⚠️ Asian BMI Cutoffs Are Different
In many Asian countries, 23 and above is considered overweight (not 25). This is because Asian populations tend to have higher body fat percentages and visceral fat risks at lower BMIs.
BMI Chart by Height and Weight
| Height \ Weight | 110 lbs | 121 lbs | 132 lbs | 143 lbs | 154 lbs | 165 lbs | 176 lbs | 187 lbs |
|---|---|---|---|---|---|---|---|---|
| 5'1" (155cm) | 20.8 | 22.9 | 25.0 | 27.1 | 29.1 | 31.2 | 33.3 | 35.4 |
| 5'3" (160cm) | 19.5 | 21.5 | 23.4 | 25.4 | 27.3 | 29.3 | 31.3 | 33.2 |
| 5'5" (165cm) | 18.4 | 20.2 | 22.0 | 23.9 | 25.7 | 27.5 | 29.4 | 31.2 |
| 5'7" (170cm) | 17.3 | 19.0 | 20.8 | 22.5 | 24.2 | 26.0 | 27.7 | 29.4 |
| 5'9" (175cm) | 16.3 | 18.0 | 19.6 | 21.2 | 22.9 | 24.5 | 26.1 | 27.8 |
| 5'11" (180cm) | 15.4 | 17.0 | 18.5 | 20.1 | 21.6 | 23.1 | 24.7 | 26.2 |
| 6'1" (185cm) | 14.6 | 16.1 | 17.5 | 19.0 | 20.5 | 21.9 | 23.4 | 24.8 |
Limitations of BMI
BMI is convenient, but it doesn't tell the whole story.
💪
Muscular People
Muscle weighs more than fat. Athletes and bodybuilders may have a high BMI but low body fat.
👴
Older Adults
With age, muscle mass decreases and body fat increases. A normal BMI may still mean high body fat percentage.
🧒
Children & Teens
BMI meaning varies by age and sex in growing children. Pediatric growth charts should be used instead.
🤰
Pregnant Women
Weight gain during pregnancy is natural. Use pre-pregnancy BMI to assess appropriate weight gain.
Other Metrics to Consider
If BMI alone isn't enough, check these additional indicators:
| Metric | How to Measure | Risk Threshold |
|---|---|---|
| Waist Circumference | Measure at navel level | Men: >40 in (102 cm), Women: >35 in (88 cm) |
| Body Fat % | Body composition analyzer | Men: >25%, Women: >30% |
| Waist-to-Hip Ratio (WHR) | Waist ÷ Hip circumference | Men: >0.9, Women: >0.85 |
💡 Simplest Extra Check
Grab a tape measure and check your waist circumference. Even if your BMI is normal, a large waist may indicate excess visceral fat.
Tips by BMI Range
Underweight (Below 18.5)
- Focus on balanced nutrition, not just eating more
- Increase protein intake and add strength training
- If persistently underweight, consult a doctor
Normal (18.5–24.9)
- Maintain your current healthy habits
- Get regular checkups to monitor body fat and waist circumference
Overweight (25–29.9)
- Lifestyle changes work best before obesity sets in
- Start with 30 minutes of walking per day
- Reducing refined carbs (bread, pasta, sugar) can make a noticeable difference
Obese (30 and above)
- Combine diet management with aerobic exercise
- Aim for 1–2 lbs per week — crash diets backfire
- If BMI is 35+, consider consulting a healthcare professional
Calculate Your BMI Now
Enter your height and weight to get your BMI and health assessment instantly. It's free and no sign-up required.