BMI Calculator
Enter your height and weight to get your Body Mass Index (BMI) and category. BMI is a quick screening number, useful as a starting point but blind to muscle versus fat.
Your results
How it works
- 1BMI is your weight in kilograms divided by your height in metres squared.
- 2Categories: under 18.5 underweight, 18.5-24.9 normal, 25-29.9 overweight, 30+ obese.
- 3Because it ignores muscle mass, very muscular people can read as overweight despite low body fat.
Frequently asked questions
What is a healthy BMI?
A BMI between 18.5 and 24.9 is classed as the healthy range for most adults. It is a screening tool, not a diagnosis, so consider it alongside body composition and health markers.
Is BMI accurate for athletes?
Not really. BMI cannot tell muscle from fat, so muscular athletes often score as overweight despite being lean. Use body-fat measurements for a truer picture.
Should I use BMI or body fat percentage?
Body fat percentage describes your composition more accurately, but BMI is faster and needs no special tools. Use BMI as a quick check and body fat for detail.
Using the result
What the numbers are
An estimate for an average person with your stats. Formulas like Mifflin-St Jeor are accurate to roughly plus or minus ten percent for most people, which is close enough to start and never close enough to argue with the scale.
How to use them
Eat at the calculated intake for two to three weeks and weigh yourself consistently. If the trend is not moving the way you want, adjust the intake by a few hundred calories rather than recalculating from scratch.
When to stop guessing
If you have been adjusting for months without progress, the missing piece is usually programming and accountability rather than a better number. That is what a coach on Trainera does.
What this calculator cannot know
Every formula here works from height, weight, age, sex and activity, which is most of the picture and not all of it. It does not know your training history, your medication, your thyroid, how well you sleep, how much you actually move outside training, or how honestly you log food. Treat the output as a starting estimate: pregnant and breastfeeding women, children, competitive athletes at very low body fat and anyone managing a medical condition should get a number from a doctor or dietitian instead of from a form. Nothing here is medical advice.
Related calculators
Turn these numbers into a real plan
Train on your own with Trainera's free workout and diet tracker, or get matched with a certified personal trainer who builds your plan around these numbers.