Skip to main content

BMI Calculator

Calculate your Body Mass Index in metric or imperial units. See healthy weight range and category.

Your BMI
22.9
Normal Weight
Your BMI
22.9
Normal Weight
BMI prime
0.91
Ponderal index
13.1
Healthy weight range (kg)
56.7 – 76.3

  • 100% private

    All math runs in your browser. Nothing leaves your device.

  • Formula-verified

    Each calculator is unit-tested against authoritative sources.

  • Instant results

    Static-rendered pages. Sub-second loads on any device.

  • Works offline

    Visit once and it keeps working without an internet connection.

How to use the BMI Calculator

  1. 1

    Enter your inputs

    Fill in the required fields at the top of the bmi calculator. Each input shows a default placeholder so you can see the expected format and units before you type.

  2. 2

    Adjust assumptions and options

    Use the toggles, sliders and dropdowns to tailor the calculation to your situation — currency, country, time period, advanced options and any optional fields all change the result in real time.

  3. 3

    Review the result

    The result card updates instantly as you type. Read the headline number, then check the breakdown, chart and any per-period schedule to understand how the inputs combined to produce the answer.

  4. 4

    Compare scenarios

    Change one input at a time to see how sensitive the result is to that variable. This is how you build intuition: small changes that move the answer a lot are the levers that matter.

  5. 5

    Share or save your result

    Copy the shareable link to send the exact scenario to someone else, or use your browser to print or save the page. The URL preserves every input so the recipient sees the same answer you do.

Frequently Asked Questions

  • Body Mass Index is a screening measure: weight (kg) ÷ height² (m²). It estimates whether someone is underweight, healthy weight, overweight or obese based on population averages.

  • WHO classifies 18.5–24.9 as healthy weight, 25.0–29.9 as overweight, 30.0+ as obese. Different ethnic groups (e.g., South Asian) may have lower healthy thresholds.

  • No — BMI overestimates body fat in muscular individuals and underestimates it in older adults with low muscle mass. It's a population screening tool, not an individual diagnostic.

  • Children and teens use age- and sex-specific percentiles (CDC growth charts), not adult BMI categories. Our calculator covers adults — refer to a pediatrician for child assessment.

  • BMI Prime = BMI ÷ 25. It expresses BMI as a ratio to the upper end of the normal range. A BMI Prime of 1.0 = BMI 25, 1.2 = BMI 30, etc.

  • PI = weight (kg) ÷ height³ (m³). It's sometimes more accurate for very tall or short people because BMI under- or over-estimates them.

  • Severe Thinness <16, Moderate Thinness 16-16.9, Mild Thinness 17-18.4, Normal 18.5-24.9, Pre-obesity 25-29.9, Obese I 30-34.9, Obese II 35-39.9, Obese III 40+.

  • Sustainable weight loss: 0.5-1 kg/week via a 500-1,000 kcal/day deficit, combining diet quality and resistance + cardiovascular exercise. Consult a healthcare professional for personalised advice.

  • Waist circumference is a better measure of abdominal fat and metabolic risk. Combine BMI + waist measurement for a fuller picture: men >102 cm or women >88 cm carry elevated risk regardless of BMI.

  • Yes — only the formula changes. Imperial: BMI = (weight lbs × 703) ÷ (height inches)². The result and categories are identical.

Related Calculators

Calorie Calculator (TDEE)

Calculate your daily calorie needs for weight loss, maintenance or muscle gain using Mifflin-St Jeor.

Calculate

BMR Calculator

Calculate your Basal Metabolic Rate using three formulas: Mifflin-St Jeor, Harris-Benedict and Katch-McArdle.

Calculate

Body Fat Calculator

Calculate body fat percentage using the U.S. Navy method or Jackson-Pollock 3-site skinfold method.

Calculate

Sleep Cycle Calculator

Find the best bedtime or wake time based on 90-minute sleep cycles to wake up refreshed.

Calculate

Pregnancy Due Date Calculator

Calculate your estimated due date by LMP, conception date, IVF transfer or ultrasound.

Calculate

Ovulation Calculator

Predict your ovulation date and 6-day fertile window. Includes 6-month fertility calendar.

Calculate