BMI Calculator

What's BMI All About?

BMI (Body Mass Index) is basically a quick way to figure out if you're in a healthy weight range for your height. It's not perfect, but it's a decent starting point that doctors and health professionals use worldwide. Think of it as a rough guideline rather than the final word on your health.

The formula is dead simple: your weight in kilograms divided by your height in metres squared (BMI = kg/m²). So if you weigh 70kg and you're 1.75m tall, that's 70 ÷ (1.75 × 1.75) = 22.9. Job done.

The BMI Categories

• Under 18.5: Underweight - might need to put on a bit of weight
• 18.5-24.9: Normal weight - you're in the sweet spot
• 25-29.9: Overweight - could benefit from losing some weight
• 30+: Obese - definitely worth talking to a doctor about

Why It Matters

Having a BMI in the normal range is linked to lower risks of heart disease, diabetes, high blood pressure, and loads of other health issues. It's not a guarantee, but statistically speaking, you're playing with better odds.

That said, don't obsess over the number. It's just one piece of the puzzle when it comes to your overall health.

BMI's Limitations (And There Are Quite a Few)

Here's the thing - BMI doesn't know the difference between muscle and fat. So if you're a rugby player or bodybuilder, you might get a "overweight" result even though you're actually incredibly fit. Same goes for older adults who've lost muscle mass - they might show as "normal" when they're actually carrying too much fat.

• Athletes: High muscle mass can skew results upward
• Elderly: Muscle loss can make results misleadingly low
• Different ethnicities: Health risks vary at different BMI levels
• Doesn't consider: Where you carry fat (belly vs hips matters)
• Frame size: Naturally broad vs narrow builds

Better Ways to Track Health

BMI is just the starting point. For a fuller picture, consider:

• Waist measurement: Belly fat is particularly risky
• Body fat percentage: More accurate than BMI
• Fitness level: Can you climb stairs without getting winded?
• Blood markers: Cholesterol, blood sugar, blood pressure
• How you feel: Energy levels, sleep, mood

When to See a Doctor

If your BMI is outside the normal range, especially if it's over 30 or under 18.5, it's worth having a chat with your GP. They can look at the bigger picture and give you proper advice based on your individual situation.