Body Mass Index Calculator Online

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How to use this tool

Enter your amounts and rates for body mass index calculator, review the breakdown, then change one input at a time to compare scenarios.

Worked example

Example: 170 cm and 70 kg gives a BMI of 24.2 (Normal weight).

When to use this

• You need a quick body mass index calculator estimate.
• You are comparing offers or scenarios side by side.
• You prefer browser tools that do not require an account.

Common examples

• 70 kg and 175 cm → BMI about 22.9 (normal adult screening range).
• 180 lb and 5 ft 10 in → BMI about 25.8 (borderline overweight category for adults).
• 65 kg and 160 cm → BMI about 25.4—useful when switching from imperial height inputs.
• 62 kg, 168 cm → BMI about 22.0 for metric wellness screening context.
• 200 lb, 5 ft 4 in → BMI about 34.3—compare with metric entry for same person.

What people search for

• bmi calculator
• body mass index calculator
• bmi calculator kg cm
• bmi calculator lbs feet
• calculate bmi online

Common mistakes

• Mixing annual and monthly rates or terms.
• Forgetting taxes, insurance, or fees that change the real total.
• Treating estimates as guaranteed quotes from lenders or employers.

Related long-tail tasks

• body mass index calculator

How it works

BMI is calculated as weight in kilograms divided by height in meters squared. US units are converted to metric before calculation. Classifications follow commonly used adult BMI ranges and are for general education only.

Limitations

BMI is a population-level screening metric, not a diagnosis. Athletes, children, and pregnant users need specialized measures.

Privacy and file handling

Your data stays on your device and is not uploaded.

Accuracy & methodology

This section documents how the calculator works, what it leaves out, and when results were last reviewed. Figures are educational estimates—not professional advice—and are not labeled "current" unless tied to automatically updated reference data.

Formula source or methodology

BMI = weight (kg) ÷ height (m)². US units convert lb → kg and ft/in → meters before calculation. Classification uses WHO-style adult cut points: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obesity.

Jurisdiction

International (WHO adult categories)

Unit system

Metric (kg, cm) or US (lb, ft/in)

Rounding method

BMI rounds to one decimal place.

Assumptions

• Adult height and weight snapshot
• Standard BMI formula; not pediatric BMI-for-age

Known omissions

• Not medical advice. Does not diagnose, treat, or replace clinical assessment.
• Athletic/muscular builds, pregnancy, and ethnicity-specific ranges
• Children and teens (use child growth tool instead)
• Waist circumference or body composition

Test cases (automated)

• 70 kg, 175 cm → BMI ≈ 22.9 (normal)
• Invalid height or weight returns an error

Version & last verified

Logic version 1.0. Content and formulas last verified 2026-07-06.

Important notice

This tool provides a general estimate for educational purposes and is not medical advice. Consult a qualified healthcare professional for personal guidance.

FAQ

Frequently asked questions

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