Calculadora de IMC
Estimación educativa con calculadora de imc. Solo cribado: no es consejo médico.
Your BMI
Key points
- BMI = weight (kg) ÷ height (m)² — the Quetelet index.
- Adult results can be placed on WHO-style category bands.
- BMI does not measure body fat or muscle and is not a diagnosis.
- Athletes, older adults, pregnancy and some populations need clinical interpretation.
What BMI measures
Body mass index (BMI) is a height-and-weight screening number. DoseFirst calculates it with the Quetelet index: weight in kilograms divided by height in metres squared. It is a population tool, not a diagnosis of body fat, fitness or disease.
Adults (age 20 and over) are grouped with World Health Organization BMI ranges, including thinness grades below 18.5. Children and teens (ages 2 to 19) are grouped with CDC BMI-for-age percentiles for sex. Those two systems are not interchangeable.
BMI Calculator for Women and Men
This adult BMI calculator uses the same Quetelet formula for women and men. WHO adult classes (including the healthy BMI range of 18.5 to under 25) are also the same for both sexes.
BMI for women and BMI for men can still look different in real life: at an equivalent BMI, women often have more body fat than men and muscular men may sit in a higher BMI class without extra fat. Sex is required here because child and teen results use CDC BMI-for-age charts that differ by sex.
BMI table for adults
WHO recommended body-weight classes for adults age 20 or older. The same cutoffs are used for men and women.
| Classification | BMI range — kg/m² |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 – < 17 |
| Mild Thinness | 17 – < 18.5 |
| Normal | 18.5 – < 25 |
| Overweight | 25 – < 30 |
| Obese Class I | 30 – < 35 |
| Obese Class II | 35 – < 40 |
| Obese Class III | ≥ 40 |
BMI Chart
This BMI chart is an adult height–weight nomogram. Shaded bands are the four major WHO groups; numbered curves are BMI values you can read against height and weight.
- Underweight < 18.5
- Normal 18.5–24.9
- Overweight 25–29.9
- Obesity ≥ 30
Healthy BMI Range
For most adults, the healthy BMI range is 18.5 to under 25 kg/m². DoseFirst uses that band for healthy weight-for-height estimates and for BMI Prime (BMI ÷ 25). The same adult range applies to women and men.
A healthy BMI is a screening range, not a personal target. Athletes, older adults, pregnancy and some ethnic groups may need a different reading. Children and teens should not be scored with this adult healthy BMI band.
BMI table for children and teens, age 2–20
CDC BMI-for-age categories. DoseFirst applies these for ages 2–19. Age 20 and over uses the adult WHO table.
| Category | Percentile range |
|---|---|
| Underweight | < 5th |
| Healthy weight | 5th – < 85th |
| Overweight | 85th – < 95th |
| Obesity | ≥ 95th |
BMI chart for children and teens, age 2–20
CDC extended BMI-for-age growth charts (ages 2–20). Download the printable PDFs. Educational reference; not a substitute for clinic software.
Risks associated with being overweight
In population studies, BMI in the overweight or obesity ranges is associated with a higher chance of several conditions. This list follows commonly cited CDC educational points. It is not a personal diagnosis.
- High blood pressure
- Higher LDL cholesterol, lower HDL cholesterol and high triglycerides
- Type 2 diabetes
- Coronary heart disease
- Stroke
- Gallbladder disease
- Osteoarthritis
- Sleep apnea and breathing problems
- Some cancers (including endometrial, breast, colon, kidney, gallbladder and liver)
- Lower quality of life, including body pain and difficulty with some physical functions
- Mental health conditions such as depression and anxiety
- An increased risk of death compared with a healthy BMI, in population studies
Many people aim to keep adult BMI below 25 kg/m², but individual targets belong with a clinician who knows the rest of the health picture.
Risks associated with being underweight
Low BMI also has associated risks in population data:
- Malnutrition, vitamin deficiencies and anemia
- Osteoporosis and a higher chance of broken bones
- Reduced immune function
- Growth and development issues in children and teenagers
- Hormonal disruption of the menstrual cycle and a higher chance of early miscarriage
- Possible complications around surgery
- An increased risk of death compared with a healthy BMI, in population studies
A low BMI can sometimes signal an underlying condition, including an eating disorder. Speak with a clinician if you or someone you care for is underweight, especially when the reason is not obvious.
Limitations of BMI
BMI estimates excess body weight, not excess body fat. Body type, muscle, bone, fat distribution, age, sex, ethnicity and activity all affect how a number should be read. Use it with other measures, not alone.
In adults
- Older adults tend to have more body fat than younger adults with the same BMI.
- Women tend to have more body fat than men for an equivalent BMI.
- Muscular people and highly trained athletes may have a higher BMI from large muscle mass.
In children and adolescents
The same limits apply and height plus sexual maturation can change BMI and body fat. In children with obesity, BMI tracks excess fat better than it does in children who are only slightly above a healthy percentile, where extra weight may be fat or fat-free mass. BMI still describes body fat reasonably for most of the population when combined with other clinical information.
How to Calculate BMI
Example person: 5′10″ (70 in, 1.778 m) and 160 lb (72.57 kg). Both expressions give BMI ≈ 23.0.
| System | Formula |
|---|---|
| US customary | BMI = 703 × mass (lb) ÷ [height (in)]² = 703 × 160 ÷ 70² = 22.96 ≈ 23.0 |
| Metric (SI) | BMI = mass (kg) ÷ [height (m)]² = 72.57 ÷ 1.778² = 22.96 ≈ 23.0 |
DoseFirst converts imperial entries to kilograms and metres, then uses the SI formula, so switching units does not change the underlying math.
BMI Prime
BMI Prime is BMI divided by 25, the upper adult normal BMI used here. The formula is BMI Prime = BMI ÷ 25. Because both numbers use the same units, Prime has no unit. A value of 1.00 sits at that boundary.
Rough reading for adults: below 0.74 is underweight, 0.74 to 1 is normal, above 1 is overweight, and above 1.2 is obese. Prime is a scaled adult index and does not replace child BMI-for-age percentiles.
| Classification | BMI | BMI Prime |
|---|---|---|
| Severe Thinness | < 16 | < 0.64 |
| Moderate Thinness | 16 – < 17 | 0.64 – < 0.68 |
| Mild Thinness | 17 – < 18.5 | 0.68 – < 0.74 |
| Normal | 18.5 – < 25 | 0.74 – < 1.00 |
| Overweight | 25 – < 30 | 1.00 – < 1.20 |
| Obese Class I | 30 – < 35 | 1.20 – < 1.40 |
| Obese Class II | 35 – < 40 | 1.40 – < 1.60 |
| Obese Class III | ≥ 40 | ≥ 1.60 |
Ponderal Index
The Ponderal (Rohrer) index uses the cube of height instead of the square. DoseFirst reports the SI form: mass (kg) ÷ [height (m)]³. The same 5′10″, 160 lb example:
| System | Formula |
|---|---|
| US customary | PI = height (in) ÷ ∛mass (lb) = 70 ÷ ∛160 ≈ 12.9 |
| Metric (SI) | PI = mass (kg) ÷ [height (m)]³ = 72.57 ÷ 1.778³ ≈ 12.9 kg/m³ |
PI can be more stable than BMI at very short or very tall heights. It is still not a diagnosis.
Health disclaimer
This calculator is educational. It is not medical advice, a diagnosis or a substitute for care from a qualified clinician. Speak with a health professional before making decisions about weight, growth, or treatment.
FAQ
Common questions about the BMI Calculator
Answers
Questions this page answers
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