BMI, BMR and Calories, Explained
What BMI, BMR and TDEE actually mean, how they relate to each other, and how to use them together to set realistic, healthy goals — with calculators built in.
Three acronyms show up again and again in health and fitness: BMI, BMR and TDEE. They sound technical, but each answers a simple question, and together they give you a clear starting point for managing your weight. This guide explains what each one means and how to use them.
BMI: are you in a healthy weight range?
Body Mass Index (BMI) compares your weight to your height. It is a quick screening tool that sorts adults into underweight, healthy, overweight and obese ranges. It does not measure body fat directly — a very muscular person can register as “overweight” — but for most people it is a useful first check.
Use this converter to convert to the unit accepted by the calculator.
Example
This is a sample result, not your calculation. Enter your own values to replace it.
Enter your height and weight, then calculate your BMI.
Your BMI
—
Healthy weight range
A healthy weight for your height is —.
WHO adult classification (healthy BMI 18.5–24.9). BMI is a screening tool, not a diagnosis.
Check your entries
Enter your height and weight to calculate your BMI.
The World Health Organization classifies a BMI of 18.5–24.9 as a healthy weight. If yours falls outside that range, it is a signal to look closer, not a diagnosis. For a better picture of body composition, pair BMI with the body fat calculator.
BMR: your body at rest
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest, just to keep you alive — breathing, circulating blood, maintaining temperature. It typically accounts for 60–70% of the calories you burn each day, and it depends on your sex, age, height and weight. You can calculate it directly with the BMR calculator.
TDEE: your real daily calorie needs
Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor — how much you move and exercise. This is the number that actually matters for managing weight:
- Eat around your TDEE to maintain your weight.
- Eat below it to lose weight (a deficit of ~500 calories a day is roughly 0.5 kg per week).
- Eat above it to gain weight.
The calorie calculator below estimates your BMR and TDEE, then shows targets for each goal:
Use this converter to convert to the unit accepted by the calculator.
- Exercise: 15-30 minutes of elevated heart rate activity.
- Intense exercise: 45-120 minutes of elevated heart rate activity.
- Very intense exercise: 2+ hours of elevated heart rate activity.
Example
This is a sample result, not your calculation. Enter your own values to replace it.
Enter your age, gender, height, weight and activity level, then calculate.
The results show a number of daily calorie estimates that can be used as a guideline for how many calories to consume each day to maintain, lose, or gain weight.
- Maintain weight— — Calories/day
- Mild weight loss 0.5 lb/week— — Calories/day
- Weight loss 1 lb/week— — Calories/day
- Extreme weight loss 2 lb/week— — Calories/day
- Mild weight gain 0.5 lb/week— — Calories/day
- Weight gain 1 lb/week— — Calories/day
- Fast weight gain 2 lb/week— — Calories/day
Zigzag calorie cycling
Eating the same amount every day is not the only way to hit a weekly target. A zigzag week alternates higher and lower days around your maintenance figure, which some people find easier to stick to. Both weeks below come to the same total.
| Day | Calories |
|---|---|
| Sunday | — |
| Monday | — |
| Tuesday | — |
| Wednesday | — |
| Thursday | — |
| Friday | — |
| Saturday | — |
| Week total | — |
| Day | Calories |
|---|---|
| Sunday | — |
| Monday | — |
| Tuesday | — |
| Wednesday | — |
| Thursday | — |
| Friday | — |
| Saturday | — |
| Week total | — |
Check your entries
Enter your age, height, weight and activity level to estimate your daily calories.
Putting it together
Here is a simple, sustainable way to use all three:
- Check your BMI to see whether a weight change makes sense.
- Find your TDEE with the calorie calculator to learn your maintenance calories.
- Set a modest deficit or surplus — around 250–500 calories — for gradual, lasting change.
- Support it with protein using the protein calculator, especially if you are exercising.
Small, consistent adjustments beat drastic ones. Recalculate every few weeks as your weight changes, since your BMR and TDEE shift with it.
This guide is general educational information, not medical advice. Talk to a qualified healthcare professional about your individual health.