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Free BMI Calculator

Calculate your Body Mass Index instantly. Metric & imperial, healthy weight range, live results.

Height (cm)
Try:
Your BMI
22.9
Normal
UnderNormalOverObese
Healthy weight range
56.7 – 76.3 kg
for your height

ⓘBMI is a general screening tool, not a diagnosis. It doesn't account for muscles, bones, or body composition — and is less reliable for people under 20. Consult a doctor for personal advice.

Source: World Health Organization (WHO)

100% free• Runs locally• Metric & imperial

What your BMI means

  1. 1
    Pick your units
    Switch between metric (kg, cm) and imperial (lb, ft/in).
  2. 2
    Enter your weight and height
    BMI updates live as you type — no submit button.
  3. 3
    Read your result
    See your BMI, category, and healthy weight range at a glance.

Frequently asked questions

  • For adults, a BMI between 18.5 and 24.9 is considered a healthy weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obesity. Based on WHO ranges for adults aged 20+.

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Was this tool helpful?

92% · 131 people found this tool helpful

About this Free BMI Calculator

Body Mass Index is the World Health Organization's quick screen for under- or over-weight in adults, calculated from your weight and height. This calculator handles both metric (kilograms, centimetres) and imperial (pounds, inches) and immediately tells you which WHO category your number falls into — underweight, normal, overweight, obesity I, II, or III. It runs offline in your browser and stores nothing, so you can check yourself, a family member, or a fitness client privately.

How to use Free BMI Calculator

  1. 1

    Enter Your Values

    Fill in the input fields — the bmi calculator accepts numbers, dates, or units depending on the mode.

  2. 2

    Choose the Calculation Mode

    Pick the operation or unit you want (add, subtract, percentage, convert) using the toggles above the inputs.

  3. 3

    See the Result Live

    The answer updates instantly as you type; no need to click a "calculate" button.

  4. 4

    Copy for Your Records

    Copy the result to your clipboard or take a screenshot for reports, invoices, or homework.

Why Use Free BMI Calculator

Doing this calculation by hand every time is a waste of your attention. BMI Calculator keeps the math boring and correct so you can focus on the decision it feeds into. The formulas are transparent, the inputs are forgiving, and every result is deterministic — the same inputs always produce the same answer, which matters when you need to defend a number to a client or a manager. Toolzer's design philosophy is simple: privacy-first (no tracking, no accounts), performance-first (the page is interactive in under a second on a 3G connection), and honesty-first (no fake ratings, no dark patterns, no upsells). BMI Calculator follows the same rules as every other utility on the site. You can bookmark this page, share the URL with a colleague, or pin it to your browser's toolbar — the experience will be identical every visit, and it will keep working even if you're on airplane Wi-Fi. Real people use this tool for real work — freelancers cleaning up client deliverables, sysadmins triaging tickets, students finishing assignments — and it is tuned for those workflows, not for demo videos.

Tips & Best Practices

  • 1Double-check the units and time zones — a wrong unit is the single most common source of a wrong answer.
  • 2For legal or financial decisions, always confirm the result against your accountant, lawyer, or the primary source.
  • 3Round only at the final step; intermediate rounding compounds into a surprisingly large error.
  • 4Save the input values along with the result if you might need to audit the calculation later.
  • 5Try the edge cases (zero, negative, very large) to build intuition for how the formula behaves.

Common Use Cases

  • 1Debugging an API response, config file, or token during day-to-day development without leaving the browser.
  • 2Sharing a formatted, human-readable version of raw data with a teammate in code review or chat.
  • 3Prototyping and testing edge cases while writing unit tests or documentation.
  • 4Cleaning up data pasted from logs, spreadsheets, or third-party dashboards before importing it elsewhere.
  • 5Learning a new format, encoding, or algorithm by experimenting with real inputs and seeing the output instantly.

Frequently asked questions

Is BMI accurate for athletes?

Not always. BMI does not distinguish muscle from fat, so very muscular people may score 'overweight' while having low body fat. Use it as a screening tool, not a diagnosis.

What is a healthy BMI range?

WHO defines 18.5–24.9 as the normal range for most adults. Below 18.5 is underweight, 25–29.9 overweight, 30+ obese.

Does it work for children?

Adult BMI thresholds do not apply to children — paediatric BMI uses age and sex percentiles. Consult a paediatrician.

Do I need to create an account to use Toolzer?

No. Every utility on Toolzer is free, anonymous, and works in any modern browser without registration.

Is Toolzer safe to use with sensitive inputs?

Yes. Whenever the tool can produce an answer entirely in the browser, the data never leaves your device.

Does Toolzer work on mobile?

Yes. The interface is fully responsive and works on iOS Safari, Android Chrome, and every modern mobile browser.

Can I link to or bookmark a result?

Yes. Every Toolzer page has a clean permanent URL you can bookmark or share.

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