Your BMI and what it doesn't tell you
GymGoatWe added a BMI calculator to the site because knowing your numbers is useful. But BMI is a blunt tool, and it's worth knowing what it can and can't tell you.
What BMI is
Body Mass Index is your weight in kilograms divided by your height in metres squared. It was designed as a quick way to look at weight across large populations, not as a detailed picture of one person's health.
Where it falls short
- It can't tell muscle from fat. Muscle is dense. Plenty of people who lift regularly land in the "overweight" range while being lean and strong.
- It ignores where weight sits. Fat stored around the waist is linked to more health risk than fat elsewhere, and BMI doesn't see the difference.
- It doesn't account for age, sex or build in any detail.
So is it useless?
No. For most people it's a reasonable first check, and if your number is well outside the healthy range it's worth paying attention to. Just don't treat it as the whole story.
Better things to track alongside it
- Your waist measurement over time
- Your strength numbers in the gym
- How your clothes fit
- Energy, sleep and how you feel day to day
Our calculator also gives you an estimate of your resting calorie burn (BMR) and your daily maintenance calories. That's a useful starting point if you're planning your food around your training.
Use the numbers as a guide, not a judgement. And if you have any concerns about your weight or health, speak to your GP.
