BMI Calculator

📖 Tool Introduction

The BMI Calculator is a free health-check tool that helps you understand your weight status in seconds. Body Mass Index is one of the most widely used worldwide standards for judging whether a person is underweight, healthy or overweight, and it is simply your weight divided by the square of your height. This tool turns height and weight into friendly, synced sliders paired with number boxes: you can either type the figures directly or drag the handles, and the BMI reading updates instantly as you move, with no extra button to press. In the result area, a large number shows your current BMI, and the badge beneath it automatically takes the colour of the band you fall into — blue for underweight, green for normal, orange for overweight and red for obese. Below that, a four-colour scale bar carries a little triangular pointer that points exactly to where your BMI sits, so the whole picture is visible at a glance. Beyond the classification, the tool also works out the healthy weight range for your specific height, telling you how many kilograms away you are from the normal zone. The interface is clean and calm, ships in Simplified Chinese, Traditional Chinese and English, and runs smoothly on both phones and desktops, making it a handy companion whether you are losing fat, building muscle or simply keeping an eye on your everyday wellbeing. Because the sliders update the result live, you can experiment freely: nudge the weight up and down to feel how sensitive the index is, or lower the height by a centimetre or two to see the band shift on the scale. This makes the tool useful not only for a one-off check-up but also for tracking a diet or training programme over weeks, since you can re-run the numbers at each milestone and watch the pointer move back towards the green zone.

✨ Key Features

• Instant results: drag a slider or type a figure and the BMI updates immediately
• Four WHO bands: underweight, normal, overweight and obese shown as colour badges
• Visual scale bar: four coloured segments with a triangular pointer marking your spot
• Healthy range: derives the weight band from 18.5 to 24.9 for your exact height
• Synced controls: sliders and number boxes stay in step for smooth operation
• One-click copy: height, weight, BMI and classification can be copied to save

📝 How to Use

1. Enter your height in centimetres, or drag the height slider
2. Enter your weight in kilograms, or drag the weight slider
3. The BMI value and its coloured badge appear on the spot
4. Watch the pointer on the four-colour scale to see which band you are in
5. Click Copy result to save it, or click Example to try a sample instantly

⚠️ Notes

• Rough guide: BMI does not separate muscle from fat, so it is unsuitable for athletes and pregnant people
• Right units: enter height in centimetres and weight in kilograms, or the result will be off
• Band thresholds: this uses the general WHO cut-offs, which may differ by region or ethnicity
• Not a diagnosis: the classification is for health awareness only and cannot replace a doctor
• Privacy: every calculation runs locally in the browser and no body data is uploaded