Body Mass Index, or BMI , is one of the most commonly used tools to assess whether a person has a healthy weight for their height. While it’s not a perfect measure — and certainly doesn’t tell the whole story about someone’s health — it remains a useful starting point for understanding general health risks associated with weight.
In this article, we’ll walk you through how to calculate BMI, what the numbers mean, and take a brief look at its fascinating history.
? How to Calculate Your BMI
Calculating your Body Mass Index (BMI) is simple and can be done using either the metric system or the imperial system .
? Metric Formula:
BMI=(height in meters)2weight in kilograms
For example, if you weigh 70 kg and are 1.75 meters tall :
BMI=1.75270=3.062570≈22.86
? Imperial Formula:
BMI=((height in inches)2weight in pounds)×703
If you weigh 154 lbs and are 69 inches tall (5’9″):
BMI=(692154)×703=(4761154)×703≈22.74
? What Do the Numbers Mean?
Once you’ve calculated your BMI, you can compare it to standard categories established by health organizations like the World Health Organization (WHO) :
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
Keep in mind that BMI is a general indicator and does not distinguish between muscle mass and fat mass. Athletes or muscular individuals may have a higher BMI without being unhealthy.
? A Brief History of BMI
The concept of BMI dates back to the 19th century, long before wearable fitness trackers or digital health apps.
It was originally developed by Adolphe Quetelet, a Belgian mathematician and astronomer, in the 1830s. Quetelet created the Quetelet Index, as it was then known, to describe the average relationship between height and weight in adult populations. His goal wasn’t necessarily to diagnose individual health but rather to study human body proportions across large groups.
The index gained renewed attention in the 1970s , when American researcher Ancel Keys popularized it as a practical tool for assessing obesity in population studies. He coined the term “Body Mass Index” (BMI), which stuck.
Since then, BMI has been adopted globally by health professionals, insurance companies, and public health organizations as a quick, accessible way to screen for potential weight-related health issues.
? Why BMI Still Matters Today
Despite criticism — particularly around its limitations for individuals — BMI remains valuable in public health research and screening for risk factors such as:
- Type 2 diabetes
- Cardiovascular disease
- Hypertension
- Certain cancers
When used alongside other metrics — like waist circumference, body fat percentage, and heart rate zones — BMI becomes a more complete part of a holistic health assessment.
?♀️ Using BMI with Walking for Better Health
If you’re practicing the Japanese Walking Method or aiming for 10,000 steps per day , tracking your BMI over time can help you monitor progress toward healthier weight goals. Even small reductions in BMI can significantly improve overall health markers.
And soon, our upcoming Android and Apple app will make it even easier to track not only your walking intervals but also your BMI, heart rate zones, and fitness progress — all in one place.
✅ Final Thoughts
While BMI is not a definitive measure of health, it provides a helpful snapshot of where you stand in terms of weight relative to your height. When combined with regular physical activity — like walking — and mindful nutrition, it can be a useful tool on your journey to better health.
Understanding how to calculate BMI and where it comes from gives you the knowledge to use it wisely — and know when to look beyond the number on the scale.
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