Salud y Fitness

Calculadora de IMC

Calcula el Índice de Masa Corporal y el rango de peso saludable

Cómo Usar

Select your preferred unit system: Métrico (kg, cm) or Imperial (lb, ft/in).
Enter your height and weight.
Enter your age and sex for a more accurate healthy weight range.
Su IMC se calcula automáticamente y se muestra con su categoría y rango saludable.

Note: BMI is a screening tool, not a diagnostic tool. Consult a healthcare provider for a complete assessment.

Fórmula

BMI = weight(kg) / height²(m)

Imperial: IMC = 703 × peso(lb) / altura²(in)

Underweight< 18.5

Normal weight18.5 – 24.9

Overweight25 – 29.9

Obese (Class I)30 – 34.9

Obese (Class II)35 – 39.9

Obese (Class III)≥ 40

¿Qué es el IMC y por qué es importante?

Body Mass Index (BMI) is a numerical value derived from your height and weight that serves as a widely adopted screening metric for weight-related health risks. Developed in the early 19th century by Belgian mathematician Adolphe Quetelet and later popularized in clinical medicine, BMI has become the global standard for classifying adults into weight categories—underweight, healthy weight, overweight, and obese. Today, it is endorsed by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) as an affordable, non-invasive first-line assessment tool.

While BMI does not directly measure body fat percentage, research published in journals such as the International Journal of Obesity consistently shows that BMI is moderately correlated with more precise measures like dual-energy X-ray absorptiometry (DEXA) scans. For most adults, a BMI between 18.5 and 24.9 kg/m² is considered the healthy range associated with the lowest risk of weight-related disease.

¿Cómo se calcula el IMC? La ciencia detrás de la fórmula

The BMI formula is elegantly simple: your body weight in kilograms divided by the square of your height in metres. In imperial units, the same result is achieved by multiplying 703 by your weight in pounds divided by height in inches squared. Despite its simplicity, the formula encapsulates a useful relationship between body size and health risk for population-level screening.

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Metric: BMI = weight (kg) ÷ height² (m)
Imperial: BMI = 703 × weight (lb) ÷ height² (in)

Beyond raw BMI, our calculator also computes IMC Prime—the ratio of your BMI to the upper limit of normal (25 kg/m²). A BMI Prime below 1.0 indicates you are within or below the healthy range, while values above 1.0 signal overweight or obesity. The Wikipedia article on BMI Prime provides an in-depth discussion of this metric and its cross-population utility. The calculator additionally shows the Índice Ponderal (kg/m³), which scales more appropriately for very tall or very short individuals.

Explicación de las categorías de IMC: desde bajo peso hasta obesidad severa

The WHO classifies BMI into six distinct categories for adults aged 20 and older. Each bracket carries different health implications and recommended clinical actions:

< 18.5

Bajo peso

Puede indicar desnutrición, desequilibrios hormonales o trastornos alimentarios. Consulte a un proveedor de atención médica.

18.5 – 24.9

Peso saludable

Asociado con el menor riesgo de enfermedades crónicas relacionadas con el peso. Mantener mediante una dieta equilibrada y actividad.

25 – 29.9

Sobrepeso

Riesgo elevado de diabetes tipo 2, hipertensión y enfermedades cardiovasculares. Se recomienda modificar el estilo de vida.

30 – 34.9

Obeso (Clase I)

Alto riesgo. Se recomienda una evaluación médica y un programa estructurado de control de peso.

35 – 39.9

Obeso (Clase II)

Riesgo muy alto. A menudo se la denomina "obesidad grave". Se recomienda encarecidamente la atención especializada.

≥ 40

Obeso (Clase III)

Riesgo extremo de comorbilidades. Anteriormente denominada "obesidad mórbida". La intervención clínica inmediata es crucial.

Children & Teens (ages 2–20): BMI is interpreted differently. The CDC uses age- and sex-specific percentiles rather than fixed cutoffs. Healthy weight falls between the 5th and 85th percentile; a BMI at or above the 95th percentile is classified as obese. See the CDC's Child & Teen BMI calculator for age-adjusted results.

Riesgos para la salud del IMC anormal: lo que dice la investigación

⚠️ Risks of High BMI (Overweight & Obesity)

A BMI above 25 kg/m² has been linked in meta-analyses to a significantly elevated risk of developing serious chronic conditions. The Wikipedia overview of obesity health effects summarises decades of epidemiological evidence:

Type 2 diabetes — up to 7× higher lifetime risk
Coronary artery disease & stroke
Hypertension (high blood pressure)
Obstructive sleep apnea
Non-alcoholic fatty liver disease (NAFLD)
Certain cancers (breast, colon, endometrial, kidney)
Osteoarthritis of the knee and hip
Reduced psychological wellbeing & quality of life

❄️ Riesgos de un IMC bajo (bajo peso)

Being underweight (BMI < 18.5) carries its own set of serious health consequences, often overlooked compared to obesity-related discourse:

Malnutrition and micronutrient deficiencies
Anemia and impaired immune function
Osteoporosis and increased fracture risk
Delayed wound healing
Fertility issues and menstrual irregularities
Muscle wasting (sarcopenia)
Greater surgical complication rates
All-cause mortality risk comparable to Class I obesity

Limitaciones del IMC: lo que este número no puede decirle

BMI is a population-level screening metric, not a personalised diagnostic tool. Understanding its limitations helps you put your result in the right context:

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Athletes & Highly Muscular Individuals — Muscle is denser than fat. A trained athlete may have a BMI in the "overweight" range while carrying very little body fat. Use our Calculadora de Grasa Corporal for a more accurate picture.

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Older Adults — Ageing naturally shifts body composition toward higher fat and lower muscle mass, even at the same BMI. Seniors often need additional assessments such as waist circumference or grip strength tests.

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Ethnic Differences — Research shows that people of South, East, and Southeast Asian descent face elevated metabolic risk at lower BMI thresholds. The WHO suggests using a cutoff of 23 kg/m² for overweight and 27.5 kg/m² for obesity in these populations.

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Sex & Age Differences — Women tend to have higher body fat at the same BMI as men. Children and teens require age- and sex-specific percentile charts, not adult cutoffs.

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Pregnancy — BMI is not meaningful during pregnancy as weight gain is expected and healthy. Pre-pregnancy BMI may be used as a reference point for gestational weight gain recommendations.

For a deeper dive into the science and controversy surrounding BMI, the Wikipedia section on BMI limitations and this New England Journal of Medicine perspective on BMI and obesity offer balanced, evidence-based perspectives.

Cómo alcanzar y mantener un IMC saludable

Whether your goal is to lower an elevated BMI or build mass from an underweight baseline, sustainable lifestyle changes consistently outperform short-term diets. Key evidence-based strategies include:

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Nutrición equilibrada

Focus on whole foods, adequate protein (1.6–2.2 g/kg body weight for muscle retention), and a moderate caloric deficit or surplus. Use our Calculadora de Calorías to find your target intake.

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Actividad física regular

The WHO recommends at least 150–300 minutes of moderate-intensity aerobic activity per week, plus muscle-strengthening exercises on 2+ days. Check our Calculadora de TDEE to plan your energy expenditure.

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Sueño de calidad

Chronic sleep deprivation elevates hunger hormones (ghrelin) and suppresses satiety signals (leptin), making weight management significantly harder. Aim for 7–9 hours per night.

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Manejo del estrés

Sustained high cortisol promotes fat accumulation—particularly visceral abdominal fat—independent of caloric intake. Mindfulness, yoga, and adequate social support all help.

Combining BMI tracking with complementary tools gives a fuller picture of your health trajectory. We recommend also monitoring your Basal Metabolic Rate (BMR), body fat percentage, and ideal weight range to set realistic, personalised goals.

Preguntas frecuentes sobre el IMC

¿Es peligroso un IMC de 25?

A BMI of exactly 25 kg/m² sits at the boundary between "healthy weight" and "overweight" categories. By itself, this value is not dangerous, but it signals the point at which statistical health risk begins to increase. Context matters enormously: waist circumference, blood pressure, blood glucose, and cholesterol levels paint a more complete picture than BMI alone.

¿Qué es un IMC saludable para mujeres frente a hombres?

The WHO applies the same BMI cutoffs (18.5–24.9 for healthy weight) to both sexes. However, at any given BMI, women typically carry 5–10% more body fat than men due to hormonal and reproductive factors. This is physiologically normal and does not inherently imply elevated health risk.

¿Puedo tener un IMC saludable y aun así no ser saludable?

Yes. The concept of "metabolically obese, normal weight" (MONW) describes individuals with a normal BMI who carry excess visceral fat and have metabolic risk factors such as insulin resistance, dyslipidemia, or hypertension. Conversely, some individuals with a BMI just above 25 are metabolically healthy. This underscores the importance of comprehensive health assessments beyond BMI alone.

¿Con qué frecuencia debo comprobar mi IMC?

For most adults, checking BMI every 3–6 months is sufficient to track meaningful trends. Daily fluctuations in body weight (due to hydration, meals, clothing) can mask true changes, so tracking weekly averages is more informative than single readings.

¿Qué es BMI Prime y por qué es útil?

BMI Prime is your BMI divided by 25 (the upper limit of normal). A value of 1.00 means you are exactly at the boundary; values below 1.00 indicate healthy or underweight status, while values above 1.00 indicate overweight or obesity. BMI Prime is particularly useful for communicating deviation from the healthy range in a simple, percentage-based format.

Related Health Calculators

Tracking your BMI alongside other health metrics provides a comprehensive view of your overall wellbeing. Explore our suite of free health tools:

References & Further Reading

World Health Organization. Obesity and Overweight Fact Sheet. WHO, 2024.
Centers for Disease Control and Prevention. About Body Mass Index. CDC, 2024.
Wikipedia contributors. Body Mass Index. Wikipedia, The Free Encyclopedia.
Wikipedia contributors. Obesity — Health Effects and Epidemiology. Wikipedia, The Free Encyclopedia.
Flegal KM, et al. Association of All-Cause Mortality with Overweight and Obesity Using Standard BMI Categories. JAMA, 2013.
Nuttall FQ. Body Mass Index: Obesity, BMI, and Health — A Critical Review. Nutrition Today, 2015.
WHO Expert Consultation. Appropriate body-mass index for Asian populations. The Lancet, 2004.