What is a healthy BMI?

A BMI between 18.5 and 24.9 is considered normal weight. Below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is classified as obese. However, BMI does not account for muscle mass, bone density, or body composition.

BMI is a useful screening tool but has limitations. It may overestimate body fat in athletes with high muscle mass and underestimate it in older adults who have lost muscle. It does not distinguish between fat and lean tissue.

What is a good BMI for my age?

For adults, the standard BMI categories apply regardless of age (18.5-24.9 is normal). However, older adults (65+) may have healthier outcomes at a slightly higher BMI (23-27). For children and teens, BMI is interpreted using age- and sex-specific growth charts.

Can I have a healthy BMI but still have too much body fat?

Yes. This is sometimes called "normal weight obesity" or "skinny fat." A person with low muscle mass and high body fat can fall in the normal BMI range while still carrying unhealthy levels of visceral fat. Body fat percentage tests give a more accurate picture.

Free BMI Calculator

Calculate your Body Mass Index (BMI) to assess if your weight is healthy for your height.

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Weight

lbs

Height (feet)

Height (inches)

BMI

24.4

BMI vs Weight

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How BMI Works

BMI divides your weight by your height squared. That's it. The number it produces places you into one of four categories: underweight (below 18.5), normal (18.5 to 24.9), overweight (25 to 29.9), or obese (30+). Doctors use it as a quick screening tool because it takes two seconds and needs no equipment.

The Formula

BMI = weight (kg) / height (m)^2

Or in imperial units: BMI = weight (lbs) * 703 / height (inches)^2

When to Use This

BMI is a rough population-level indicator. It works well for identifying weight-related health risk in sedentary adults who don't have unusual muscle mass. If your doctor mentions BMI at a checkup, this is the formula they're using.

What BMI Doesn't Tell You

BMI can't distinguish muscle from fat. A 5'10" person weighing 200 lbs gets a BMI of 28.7 (overweight) whether they're a competitive athlete or sedentary. It also doesn't account for where you carry weight. Belly fat around internal organs carries more health risk than fat on your hips or thighs, and BMI ignores that entirely.

For a more complete picture, consider waist-to-hip ratio, body fat percentage, or a DEXA scan.

How to Read Your Result

BMI RangeCategory Below 18.5Underweight 18.5 to 24.9Normal weight 25.0 to 29.9Overweight 30.0+Obese

These ranges were set by the WHO and apply to adults over 20. They don't apply to children, pregnant women, or highly muscular individuals.

Common Mistakes

Mixing up units. Using pounds with the metric formula (or kg with imperial) gives a meaningless number.

Applying BMI categories to children. Pediatric BMI uses age-specific percentile charts, not the adult cutoffs.

Treating BMI as a diagnosis. A high BMI isn't a disease. It's a screening number that might prompt further evaluation.

Example Calculation

A person weighing 170 lbs at 5 feet 10 inches.

01Height in inches = 5 x 12 + 10 = 70 inches
02BMI = (170 x 703) / (70 x 70)
03= 119,510 / 4,900
04= 24.4 (Normal weight)

Example Calculations

What is the BMI for a 6-foot male weighing 180 lbs?

BMI = 24.4 (Normal weight)

1.Height: 6'0" = 72 inches
2.Weight: 180 lbs
3.BMI = 703 × weight / height² = 703 × 180 / 72²
4.BMI = 126,540 / 5,184 = 24.4
5.Category: Normal weight (18.5–24.9)

What is the BMI for a 5'5" female weighing 140 lbs?

BMI = 23.3 (Normal weight)

1.Height: 5'5" = 65 inches
2.Weight: 140 lbs
3.BMI = 703 × 140 / 65² = 98,420 / 4,225
4.BMI = 23.3
5.Category: Normal weight (18.5–24.9)

What is the BMI for someone who is 5'10" and 200 lbs?

BMI = 28.7 (Overweight)

1.Height: 5'10" = 70 inches
2.Weight: 200 lbs
3.BMI = 703 × 200 / 70² = 140,600 / 4,900
4.BMI = 28.7
5.Category: Overweight (25.0–29.9)

What is a healthy weight for 5'8"?

125–163 lbs

1.Height: 5'8" = 68 inches
2.Healthy BMI range: 18.5–24.9
3.Minimum weight: 18.5 × 68² / 703 = 121.7 ≈ 122 lbs
4.Maximum weight: 24.9 × 68² / 703 = 163.8 ≈ 164 lbs
5.Healthy weight range: approximately 122–164 lbs

What BMI is considered obese?

BMI of 30 or higher

1.Underweight: BMI below 18.5
2.Normal weight: BMI 18.5–24.9
3.Overweight: BMI 25.0–29.9
4.Obese: BMI 30.0 or higher
5.Severely obese: BMI 40.0 or higher

Frequently Asked Questions

Learn More

Understanding BMI: What It Means and How to Calculate It

Learn what BMI is, how to calculate it, what the ranges mean, and the limitations of body mass index as a health metric. Comprehensive guide with formulas and context.