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BMI Calculator

Check your body mass index

Units

Your BMI

24.4

Category

Healthy Weight

Ideal

153 lbs

Range

129 lbs - 174 lbs

ft
in
lbs

Your BMI

24.4

Healthy Weight
1618.525303540
Ideal Weight

153 lbs

Healthy Range

129 lbs - 174 lbs

Great! You're at a healthy weight

Maintain your current lifestyle with balanced diet and regular exercise.

BMI Categories

Underweight
16 - 18.5
Healthy Weight
18.5 - 25
Overweight
25 - 30
Obese Class I
30 - 35
Obese Class II
35 - 40
Obese Class III
40 - 40+

About BMI

BMI is a screening tool, not a diagnostic measure. It doesn't account for muscle mass, bone density, age, or ethnicity. Consult a healthcare provider for personalized advice.

How This Calculator Works

Uses the WHO BMI classification standard with CDC-recommended weight categories. Ranges: underweight (<18.5), normal (18.5-24.9), overweight (25-29.9), obese (30+).

Sources: World Health Organization (WHO), Centers for Disease Control and Prevention (CDC)

Frequently Asked Questions

Q

What is BMI?

Body Mass Index (BMI) is a screening tool that estimates body fat using your height and weight. Formula: BMI = weight (kg) / height (m)². For example, a person weighing 70 kg and 1.75 m tall has a BMI of 22.9 (70 ÷ 1.75² = 22.9), which falls in the healthy range.

  • Formula (metric): weight (kg) ÷ [height (m)]²
  • Formula (imperial): [weight (lbs) ÷ height (inches)²] × 703
  • Used by doctors worldwide as initial health screening
  • Takes 30 seconds to calculate with our tool

BMI was developed in the 1830s by Belgian mathematician Adolphe Quetlet. While not perfect, it's a quick, inexpensive way to screen for weight categories that may lead to health problems. The CDC and WHO use BMI as a standard health assessment tool.

Q

What is a healthy BMI range?

A healthy BMI ranges from 18.5 to 24.9 for adults. BMI under 18.5 indicates underweight, 25-29.9 is overweight, and 30+ is obese. For example, someone 5'9" should weigh between 125-169 lbs to maintain a healthy BMI.

  • Underweight (<18.5): Risk of malnutrition, osteoporosis, weakened immunity
  • Healthy (18.5-24.9): Lowest risk for weight-related disease
  • Overweight (25-29.9): Increased risk of heart disease and diabetes
  • Obese Class I (30-34.9): High risk — lifestyle changes recommended
  • Obese Class II-III (35+): Very high risk — medical consultation advised
BMI RangeCategoryHealth Risk
Below 18.5UnderweightIncreased
18.5 - 24.9Healthy WeightLow
25.0 - 29.9OverweightModerate
30.0 - 34.9Obese (Class I)High
35.0 - 39.9Obese (Class II)Very High
40.0+Obese (Class III)Extremely High

BMI categories are based on extensive research linking weight ranges to health outcomes. Higher BMI increases risk of heart disease, type 2 diabetes, high blood pressure, and certain cancers. According to the National Institutes of Health, maintaining a BMI in the healthy range can significantly reduce these risks.

Q

Is BMI accurate for everyone?

BMI is accurate for most adults but has limitations. It doesn't account for muscle mass, bone density, body composition, or age/sex differences. Athletes with high muscle mass may have "overweight" BMI but low body fat. Elderly people may have "healthy" BMI but insufficient muscle mass.

  • Not accurate for bodybuilders or athletes (high muscle mass)
  • May not reflect body fat in elderly (loss of muscle)
  • Doesn't distinguish between visceral and subcutaneous fat
  • Asian populations may have health risks at lower BMI (23+)
  • Children and teens need age-specific BMI percentiles

For example, a muscular athlete weighing 200 lbs at 5'10" has a BMI of 28.7 (technically "overweight"), but their body fat percentage might be just 10%. Conversely, an elderly person with low muscle mass could have a "healthy" BMI but high body fat. Use BMI as one tool alongside waist circumference, body fat percentage, and overall health markers.

Q

How do I calculate my BMI?

Calculate BMI by dividing weight in kilograms by height in meters squared. Metric example: 70 kg ÷ (1.75 m)² = 70 ÷ 3.06 = 22.9 BMI. Imperial example: (154 lbs ÷ 69 inches²) × 703 = (154 ÷ 4,761) × 703 = 22.7 BMI.

  • Step 1: Measure your weight (without clothes)
  • Step 2: Measure your height (without shoes)
  • Step 3: Use our calculator or apply formula
  • Step 4: Compare result to BMI categories above
  • Green zone (18.5-24.9): No action needed
  • Yellow zone (25-29.9): Consider lifestyle changes
Height120 lbs140 lbs160 lbs180 lbs200 lbs
5'2" (157 cm)21.925.629.332.936.6
5'4" (163 cm)20.624.027.530.934.3
5'7" (170 cm)18.821.925.128.231.3
5'10" (178 cm)17.220.123.025.828.7
6'0" (183 cm)16.319.021.724.427.1
6'2" (188 cm)15.418.020.523.125.7
Q

What BMI is considered overweight?

BMI of 25.0 to 29.9 is classified as overweight. For someone 5'9" tall, overweight means weighing 170-202 lbs. For 5'4", it's 146-174 lbs. Being overweight increases health risks moderately compared to healthy weight range (18.5-24.9).

  • Overweight is BMI 25.0-29.9 — a moderate health risk category
  • Losing 5-10% of body weight can significantly reduce health risks
  • Waist circumference adds context: >40 in (men) or >35 in (women) = higher risk
  • Asian populations may face increased risks at lower BMI thresholds (23+)
HeightHealthy WeightOverweight RangeObese (30+ BMI)
5'2" (157 cm)101-136 lbs137-163 lbs164+ lbs
5'4" (163 cm)108-145 lbs146-174 lbs175+ lbs
5'7" (170 cm)118-159 lbs160-191 lbs192+ lbs
5'9" (175 cm)125-168 lbs169-202 lbs203+ lbs
6'0" (183 cm)140-183 lbs184-220 lbs221+ lbs
6'2" (188 cm)148-193 lbs194-232 lbs233+ lbs

Example Calculations

1Healthy Weight Adult

Inputs

Weight154 lbs (70 kg)
Height5'9" (175 cm)

Result

BMI22.9
CategoryHealthy Weight
Healthy Range125-168 lbs
Ideal Weight (BMI 22)149 lbs (68 kg)

BMI = 70 / (1.75)² = 70 / 3.0625 = 22.9. This falls in the healthy range (18.5-24.9). Healthy weight range for 5'9": 18.5 × 1.75² = 56.7 kg (125 lbs) to 24.9 × 1.75² = 76.2 kg (168 lbs). Ideal weight at BMI 22: 22 × 3.0625 = 67.4 kg (149 lbs).

2Overweight Example

Inputs

Weight190 lbs (86 kg)
Height5'9" (175 cm)

Result

BMI28.1
CategoryOverweight
To Reach Healthy BMILose 22 lbs
Healthy Range125-168 lbs

BMI = 86 / (1.75)² = 86 / 3.0625 = 28.1. This is in the overweight range (25-29.9). To reach BMI 24.9: 24.9 × 3.0625 = 76.3 kg (168 lbs). Weight to lose: 86 - 76.3 = 9.7 kg (22 lbs). Healthy range: 125-168 lbs.

3Metric Calculation

Inputs

Weight65 kg
Height1.70 m

Result

BMI22.5
CategoryHealthy Weight
Calculation65 ÷ (1.70)² = 22.5
Healthy Range53-72 kg

BMI = 65 / (1.70)² = 65 / 2.89 = 22.5. Healthy range for 1.70m: 18.5 × 2.89 = 53.5 kg to 24.9 × 2.89 = 72.0 kg. Ideal weight (BMI 22): 22 × 2.89 = 63.6 kg.

Formulas Used

BMI Formula (Metric)

BMI = weight (kg) / height (m)²

Standard metric formula used worldwide.

Where:

weight= Body weight in kilograms
height= Height in meters

Source: World Health Organization (WHO) BMI Classification

BMI Formula (Imperial)

BMI = [weight (lbs) / height (in)²] × 703

Imperial formula with conversion factor.

Where:

703= Conversion factor for imperial units

Source: Centers for Disease Control and Prevention (CDC)

Understanding BMI

1

BMI Formula: Metric and Imperial Calculations

BMI divides weight in kilograms by height in meters squared — a 70 kg person at 1.75 m tall scores 22.9, landing in the healthy range of 18.5–24.9. The imperial formula multiplies (weight in lbs ÷ height in inches²) by 703, producing the same result. Both formulas yield a single number that the WHO maps to 7 categories ranging from severely underweight (<16.0) to obese class III (40.0+).

The metric formula is straightforward: BMI = kg / m². For a 5’9″ (175 cm), 190 lb (86 kg) person: 86 ÷ 3.0625 = 28.1, placing them in the overweight category. The imperial version is identical mathematically — (190 ÷ 69²) × 703 = 28.1. Use the body fat percentage calculator alongside BMI for a more complete assessment of body composition.

BMI RangeWHO CategoryRisk LevelExample (5’9″)
Below 16.0Severely UnderweightHigh<121 lbs
16.0–16.9Moderately UnderweightModerate121–128 lbs
17.0–18.4Mildly UnderweightLow–Moderate129–139 lbs
18.5–24.9Healthy WeightLow140–188 lbs
25.0–29.9OverweightModerate189–226 lbs
30.0–34.9Obese Class IHigh227–264 lbs
35.0+Obese Class II–IIIVery High265+ lbs
2

Why BMI Fails: 2025 Research on Limitations

A 2025 University of Florida Health study found that BMI alone is a poor predictor of mortality risk — individuals with identical BMIs showed widely different health outcomes depending on body composition. The American Medical Association echoed this in 2023, stating BMI should never serve as the sole diagnostic measure for weight-related health assessment.

Consider a 6-foot sprinter weighing 200 lbs: their BMI of 27.1 classifies them as overweight, yet their body fat may be just 8–10%. Conversely, a sedentary person with BMI 23.5 (technically “healthy”) can carry 30%+ body fat with significant visceral fat deposits. Studies estimate BMI misclassifies body fat status in roughly 50% of women and 25% of men.

The core problem is mathematical: BMI uses total weight, making no distinction between muscle, bone, water, and fat. A kilogram of muscle occupies about 18% less volume than a kilogram of fat, so muscular individuals systematically score higher. The Body Roundness Index calculator offers a waist-based alternative that better captures visceral fat distribution.

The AMA recommends using BMI alongside waist circumference, body fat percentage, and metabolic markers — never as a standalone diagnosis.

3

Complementary Body Metrics: BF%, BRI, and BSA

3 metrics fill the gaps BMI leaves. Body fat percentage (measured via the US Navy method at ±3–4% accuracy or DEXA scan at ±1–2% for $50–$150) directly quantifies fat tissue. Athletic men typically range 6–14%, while athletic women range 14–20%. Unlike BMI, body fat percentage correctly classifies muscular individuals.

The Body Roundness Index (BRI) models the torso as an ellipse using only height and waist circumference. A BRI above 6.9 correlates with 49% higher all-cause mortality risk according to Thomas et al. (2013). BRI specifically targets visceral fat — the metabolically dangerous fat around organs that BMI cannot detect. Calculate yours with the BRI calculator.

Body Surface Area (BSA) matters primarily in clinical settings — averaging 1.7 m² for adults — where it determines drug dosing for chemotherapy and cardiac assessments. While less relevant for daily health tracking, BSA paired with BMI helps clinicians evaluate patients more holistically. The BSA calculator uses the Mosteller formula for quick estimates.

MetricWhat It MeasuresKey Advantage Over BMIAccuracy
Body Fat %Actual fat tissue ratioDistinguishes muscle from fat±3–4% (Navy) / ±1–2% (DEXA)
BRICentral body fat (visceral)Targets dangerous belly fatr = 0.77 vs DEXA visceral
Waist-to-HeightCentral obesitySimple threshold (>0.5 = risk)Validated in 300K+ subjects
BSATotal body surface areaClinical drug dosing±2–3% (Mosteller)
4

When BMI Still Works: Population Screening and Trends

Despite individual limitations, BMI remains the most practical screening tool for populations of 1,000+ people where body composition testing is infeasible. The CDC uses BMI to track national obesity trends — the U.S. adult obesity rate rose from 30.5% in 1999 to 41.9% in 2020, a shift BMI captured accurately at scale.

For personal tracking, BMI works best as a trend indicator rather than an absolute number. A BMI rising from 24.0 to 27.5 over 2 years signals meaningful fat gain for most non-athletes, even if the absolute values lack precision. Combined with waist circumference trends and quarterly BMR calculations to track metabolic changes, BMI contributes useful data points to a broader health picture.

BMI Categories: Where Most Adults Fall0%10%20%30%40%Under-weightHealthy31%Over-weight33%Obese42%1.6%Healthy 18.5–24.9Overweight 25–29.9Obese 30+
5

How to Use This BMI Calculator

Enter your weight and height in either metric (kg/cm) or imperial (lbs/inches) units — the calculator converts automatically. Results include your BMI value, WHO category, healthy weight range for your height, and the distance to the nearest category boundary in pounds or kilograms.

For the most accurate reading, weigh yourself in the morning before eating, wearing minimal clothing. Height should be measured without shoes. Repeat weekly at the same time to track trends rather than fixating on any single reading — daily weight can fluctuate by 2–4 lbs from water retention alone.

  1. 1

    Enter your weight

    Use the unit toggle to switch between lbs and kg. Morning weight before breakfast is most consistent.

  2. 2

    Enter your height

    Switch between feet/inches and centimeters. Measure without shoes against a flat wall.

  3. 3

    Review your BMI and category

    The result shows your BMI, WHO category, healthy weight range, and how far you are from category boundaries.

  4. 4

    Explore complementary metrics

    Use body fat percentage, BRI, or waist-to-height ratio calculators for a fuller health picture beyond BMI alone.

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Waist-to-Height Ratio Calculator

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Last Updated: Mar 26, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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