BMI Calculator

Calculate your Body Mass Index (BMI), health category, and healthy weight range. Supports metric and US imperial units.

Calculator Inputs

Switch between Imperial and Metric units.
Used for adult body composition percentiles.
yrs
Age in years.
ft
Feet.
in
Inches.
lbs
Current body weight.

Calculated Results

Your Body Mass Index (BMI)
22.5 (Normal Weight)
Healthy BMI Range 18.5 – 24.9
Healthy Weight Range 128 – 173 lbs
BMI Prime 0.90
Values calculate live as you adjust inputs.

About BMI Calculator

What is the BMI Calculator?

The BMI Calculator is an enterprise-grade calculation tool designed to compute exact mathematical, financial, or scientific parameters based on peer-reviewed formulas.

How to Use This Calculator

  1. Enter your primary input variables in the input fields above.
  2. Select your desired measurement units or options.
  3. Click Calculate to instantly view live outputs, step-by-step mathematical breakdowns, and formulas.

Mathematical Formula & Derivation

Our calculation engine implements verified equations approved by academic literature, WHO guidelines, IRS tax codes, or BIPM metric standards.

Frequently Asked Questions

Q: Is this calculator free to use?
A: Yes! OmniCalc Ultra provides 100% free, private, client-side calculations with zero tracking.

Scientific & Academic References

  • International System of Units (SI) Standards
  • NIST Engineering & Mathematical Reference Handbooks

What is BMI Calculator?

Body Mass Index (BMI) is a standardized screening metric established by the World Health Organization (WHO) that evaluates body mass relative to height squared.

How to Use This Calculator

  1. Select your preferred measurement units (US or Metric).
  2. Input your biological sex, age, height, and weight.
  3. View your calculated BMI score and clinical weight status classification.

The Mathematical Formula & Variables

BMI = 703 * Weight(lbs) / [Height(in)]^2, or Weight(kg) / [Height(m)]^2

Variables Definition

Symbol / Variable Name Description
BMI Body Mass Index Clinical weight-to-height ratio (kg/m²).
703 Conversion Factor Converts lbs/in² into international metric kg/m².

Step-by-Step Worked Example

Scenario: Adult standing 5 feet 10 inches (70 inches) weighing 157 pounds.

  1. Square the height in inches: 70 * 70 = 4,900.
  2. Multiply weight by conversion constant: 157 * 703 = 110,371.
  3. Divide weight product by height squared: 110,371 / 4,900 = 22.52.
  4. Classification: 22.5 falls in the Normal Healthy Weight category (18.5 – 24.9).

Result: BMI = 22.5 (Normal Healthy Weight)

Frequently Asked Questions

What is considered a normal BMI?

According to the World Health Organization and CDC, a BMI between 18.5 and 24.9 is considered normal or healthy weight for adults.

Does BMI account for muscle mass?

BMI measures excess weight rather than excess fat. Highly muscular individuals and athletes may register in the overweight category despite having low body fat.

Are BMI calculations different for women and men?

For adults aged 20 and older, standard BMI cutoffs are identical for men and women, although women typically carry more essential body fat at the same BMI.