_id

683a15ecc782e11e38d1b08d

id

29

title

BMI Calculator (Body Mass Index and BSA)

full_title

BMI Calculator (Body Mass Index and BSA)

short_title

BMI & BSA

med_description

Calculates body mass index and body surface area.

short_description

Categorizes obesity, assists some med dosing.

slug

body-mass-index-bmi-body-surface-area-bsa

description

Enter the patient’s height and weight in the BMI Calculator to calculate the Body Mass Index based on the estimated body fat.

keywords

BMI, bmi calculator, bmi calculator for women, BSA, Height and Weight, Physical activity, Weight range, Lose weight, Muscle mass, Body surface area, body mass index, body mass calc, body mass score, body index, surface area of body, bsa calc, bsa score, bmi calc, bmi score, body mass, body mass obese, body mass obesity, body mass calculator, body mass index calc, body mass underweight, body mass normal, body mass nl, body mass nml, rule out obesity, height weight, height weight calc, height weight obese, height weight score, height weight index, height weight calc, height weight underweight, height weight ratio normal, height weight nl, height weight nml, height weight ratio, body surface normal, body surface area, surface area obesity, body surface area weight, body surface height, body surface area calc, body SA, body SA calc, height weight surface, height weight surface area, surface area weight, SA weight, surface area height, sa height

complaint

[ "Weight Loss/Gain" ]

formula

Body mass index, kg/m2= weight, kg / (height, m)2 Body surface area (the Mosteller formula), m2= [ Height, cm x Weight, kg  / 3600 ]1/2

evidence

measurements

[ { "name": "Weight", "unit": "wt", "error_min": "0.5", "error_max": "620", "warn_min": "0.5", "warn_max": "500", "conversion": "0.453592", "normal_max_si": "150", "normal_max_us": "330", "normal_min_si": "1", "normal_min_us": "2", "units_si": "kg", "units_us": "lbs" }, { "name": "Height", "unit": "ht", "error_min": "0", "error_max": "90", "warn_min": "5", "warn_max": "80", "conversion": "2.54", "normal_max_si": "213", "normal_max_us": "84", "normal_min_si": "152", "normal_min_us": "60", "units_si": "cm", "units_us": "in" }, { "name": "Body Mass Index", "unit": "BMI", "error_min": "0", "error_max": "50", "warn_min": "10", "warn_max": "30", "conversion": "1", "normal_max_si": "25", "normal_max_us": "25", "normal_min_si": "20", "normal_min_us": "20", "units_si": "kg/m²", "units_us": "kg/m²" } ]

information

*Since the typical classification may underestimate the risk of cardiovascular disease associated with obesity in Asian populations, organizations like the WHO and NIH recommend lower BMI thresholds for these individuals. In this context, "overweight" is defined as a BMI of 23–24.9 kg/m² and "obesity" as a BMI of ≥25 kg/m².

refrences

{ "Clinical Practice Guidelines": [ { "href": "https://pubmed.ncbi.nlm.nih.gov/39824205/", "text": "Rubino F, Cummings DE, Eckel RH, et al. Definition and diagnostic criteria of clinical obesity. Lancet Diabetes Endocrinol. 2025;13(3):221-262." } ], "Manufacturer Website": [ { "href": "", "text": "" } ], "Original/Primary Reference": [ { "href": "https://www.ncbi.nlm.nih.gov/pubmed/16768059", "text": "Gadzik J. 'How much should I weigh?' Quetelet's equation, upper weight limits, and BMI prime.Connecticut Medicine. (2006). 70 (2): 81–8. PMID 16768059." } ], "Other References": [ { "href": "https://www.who.int/health-topics/obesity#tab=tab_1", "text": "BMI Classification. Global Database on Body Mass Index. World Health Organization. 2006. Retrieved July 27, 2012." }, { "href": "https://policysearch.ama-assn.org/policyfinder/detail/bmi?uri=%2FAMADoc%2FHOD.xml-H-440.800.xml", "text": "Support Removal of BMI as a Standard Measure in Medicine and Recognizing Culturally-Diverse and Varied Presentations of Eating Disorders H-440.800. Retrieved March 17, 2025. " }, { "href": "https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html", "text": "Adult BMI Categories, Centers for Disease Control and Prevention. Retrieved March 16, 2025." } ], "Outcomes": [ { "href": "", "text": "" } ], "Validation": [ { "href": "", "text": "" } ], "Validations": [] }

pearls

• Always use the most recent height and weight measurements to ensure accuracy.
• Remember that both BMI and BSA are part of a larger clinical context and should be used in conjunction with other assessments and patient history.

BMI:

• Does not distinguish between fat and muscle mass. 
• Tends to overestimate body fat in individuals with very high muscle mass who are otherwise healthy, and can underestimate it in older adults due to age-related muscle loss.
• The typical classification may underestimate the risk of cardiovascular disease associated with obesity in Asian populations. Organizations like the Wold Health Organization (WHO) and National Institutes of Health (NIH) recommend lower BMI thresholds for these individuals. Please see Evidence for more details.
• BMI is based primarily on data collection from non-Hispanic white populations, making its generalizability prone to inaccuracy.
• Some organizations, such as the AMA, have recognized the importance of using a variety of measures to determine an appropriate risk assessment and advise clinicians to eliminate the use of BMI as a sole indicator of risk.
• BMI should be utilized in conjunction with measurements of visceral fat, body adiposity index, waist circumference, and other metabolic/genetic factors when diagnosing obesity (Rubino et al., 2025).

BSA:

• Multiple formulas for BSA are available. This tool utilizes the Mosteller formula.
• May be less precise for neonates and infants, as well as for individuals at extreme values of height and weight.

usecase

• BMI: This calculation is routinely used during clinical evaluations to estimate the appropriateness of an individual's weight relative to their height, serving as a preliminary step in identifying patients who are underweight or overweight.
• BSA: This formula estimates an individual's total external surface area, aiding in calculating dosages for medications, such as chemotherapy, and measuring cardiac index.

reasons

BMI provides a quick estimate of adiposity, while the BSA calculation helps estimate an individual's total external surface area, which is difficult to measure directly.

next_advice

• For patients identified as underweight or overweight, consider further nutritional or physical assessments and referrals as appropriate.
• Individuals diagnosed with overweight or obesity should be counseled on diet and exercise.
• In cases involving drug dosing, especially chemotherapy, regular monitoring and dose adjustments based on changes in BSA are necessary to optimize therapeutic outcomes.

next_actions

A diagnosis of obesity can be made with a BMI of ≥30 kg/m² alone; no further confirmatory testing or measurement is required (Rubino et al., 2025).

next_management

Management should not depend solely on BMI or BSA measurements, but on these values in conjunction with other body measurements and the overall clinical picture.

diseases

[ "Cancer", "Diabetes Mellitus", "Obesity", "Renal Failure" ]

input_schema

[ { "conditionality": "", "default": null, "fhir_rules": null, "inct": null, "label_en": "<p>Weight</p>", "name": "weight", "optional": false, "tips_en": "", "type": "textbox", "unit": "wt" }, { "conditionality": "", "default": null, "fhir_rules": null, "inct": null, "label_en": "<p>Height</p>", "name": "height", "optional": false, "tips_en": "", "type": "textbox", "unit": "ht" }, { "conditionality": "", "default": null, "fhir_rules": null, "inct": null, "label_en": "<p>Target BMI</p>", "name": "target", "optional": true, "tips_en": "Optional, to determine weight required to achieve target BMI", "type": "textbox", "unit": "BMI" } ]

instructions

Use in conjunction with other measurements such as waist-hip ratio, waist circumference, visceral fat measurement, and body adiposity index.

published

2022-04-21T20:29:11.323Z

purpose

[ "Formula" ]

search_terms

[ "weight", "obesity", "overweight", "body mass index", "surface area", "bmi", "bsa", "BMI & BSA", "body surface area", "bmi and bsa" ]

seo

{ "keywords_en": "BMI, bmi calculator, bmi calculator for women, BSA, Height and Weight, Physical activity, Weight range, Lose weight, Muscle mass, Body surface area, body mass index, body mass calc, body mass score, body index, surface area of body, bsa calc, bsa score, bmi calc, bmi score, body mass, body mass obese, body mass obesity, body mass calculator, body mass index calc, body mass underweight, body mass normal, body mass nl, body mass nml, rule out obesity, height weight, height weight calc, height weight obese, height weight score, height weight index, height weight calc, height weight underweight, height weight ratio normal, height weight nl, height weight nml, height weight ratio, body surface normal, body surface area, surface area obesity, body surface area weight, body surface height, body surface area calc, body SA, body SA calc, height weight surface, height weight surface area, surface area weight, SA weight, surface area height, sa height", "meta_description_en": "Enter the patient’s height and weight in the BMI Calculator to calculate the Body Mass Index based on the estimated body fat." }

specialty

[ "Critical Care", "Emergency Medicine", "Endocrinology", "Family Practice", "Geriatrics", "Hematology and Oncology", "Hospitalist Medicine", "Internal Medicine", "OB-Gyn", "Pediatrics", "Pharmacy", "Primary Care", "Radiation Oncology", "Rehabilitation Medicine" ]

departments

[ "Endocrine and Metabolic", "Musculoskeletal" ]

tags

[]

version_number

1

versions

[]

related

[ { "calcId": 10575, "short_title_en": "BRI", "slug": "body-roundness-index-bri" }, { "calcId": 10568, "short_title_en": "Rule of Nines", "slug": "rule-nines" }, { "calcId": 10560, "short_title_en": "FFM", "slug": "fat-free-mass-ffm" } ]

ismed

false

section

[ "whenToUseViewed", "pearlsPitfallsViewed", "whyUseViewed", "nextStepsViewed", "evidenceViewed" ]

cleaned_departments

[ "endocrine", "orthopedics" ]

cleaned_use

[ "BMI:This calculation is routinely used during clinical evaluations to estimate the appropriateness of an individual's weight relative to their height, serving as a preliminary step in identifying patients who are underweight or overweight.", "BSA:This formula estimates an individual's total external surface area, aiding in calculating dosages for medications, such as chemotherapy, and measuring cardiac index." ]

pub

true