BMR Calculator
What Is BMR?
Your basal metabolic rate, or BMR, is the number of calories your body burns simply by staying alive: breathing, keeping your heart beating, maintaining body temperature, repairing cells and running your brain. It is measured at complete rest, and for most people it accounts for roughly 60 to 75 per cent of all the calories they burn in a day. Everything else — walking, working, exercising, even digesting food — sits on top of this baseline.
Knowing your BMR matters because it gives you a floor for sensible eating. Eat well below it for long periods and your body adapts by slowing down, leaving you tired, cold and hungry; eat around your total daily needs and you can plan weight loss, maintenance or muscle gain with real numbers instead of guesswork. Athletes, dieters, coaches and anyone starting a fitness plan all use BMR as the starting point, then adjust for activity to get total daily energy expenditure, known as TDEE.
How to Use This BMR Calculator
- Choose your units. Tap Metric for centimetres and kilograms, or Imperial for inches and pounds.
- Select your gender. Men and women have different equations, because body composition and hormone profiles affect resting metabolism.
- Enter your age in years. Metabolism slows gradually with age, so an honest age keeps the estimate accurate.
- Enter your height. Measure barefoot, standing straight against a wall, from floor to the top of your head.
- Enter your weight. Weigh yourself in the morning, before breakfast and after using the bathroom, for the most consistent figure.
- Pick your activity level. Be realistic: choose sedentary for a desk day with almost no exercise, moderately active for three to five workouts a week, and extremely active only if you have a physical job plus daily training.
- Click Calculate My BMR. You will see your BMR, your maintenance calories, and sensible targets for losing or gaining weight.
Worked Example: 30-Year-Old Man
Let us run the maths for a man aged 30, 178 cm tall and weighing 78 kg, who exercises three to five times a week:
- Weight term: 10 × 78 = 780
- Height term: 6.25 × 178 = 1,112.5
- Age term: 5 × 30 = 150, subtracted
- Men's constant: add 5
- BMR: 780 + 1,112.5 − 150 + 5 = 1,747.5 calories per day
- TDEE: 1,747.5 × 1.55 (moderately active) = about 2,709 calories per day
That means this man burns about 1,748 calories doing absolutely nothing, and about 2,709 calories on a typical moderately active day. Eating around 2,200 calories a day — roughly 500 below his TDEE — would give steady, sustainable weight loss of about half a kilogram a week. Try your own numbers in the tool above and compare your result with this example.
Activity Multipliers Used
| Activity level | Multiplier | What it means |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days a week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days a week |
| Very active | × 1.725 | Hard exercise 6–7 days a week |
| Extremely active | × 1.9 | Physical job plus daily training |
Tips for Using Your BMR Wisely
- Do not eat below your BMR for long. A modest deficit from your TDEE is safer and more sustainable than a crash diet pitched below your resting needs.
- Recalculate after big changes. Losing or gaining 5 kg, or changing your training sharply, shifts your BMR — run the numbers again every few months.
- Track for two to three weeks. Compare your predicted maintenance calories with your real weight trend, then adjust up or down by 100–200 calories.
- Remember muscle matters. Two people of the same weight can have different BMRs if one is far more muscular, since muscle burns more energy at rest than fat.
- Use BMR with our other tools. Pair it with the BMI calculator and the TDEE figures here to set a complete, realistic plan.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the calories you burn at complete rest, just staying alive. TDEE adds everything else — walking, work, exercise and digestion — so it is your total daily burn. BMR is the base; TDEE is the number you actually plan your eating around.
Which BMR formula does this calculator use?
The Mifflin-St Jeor equation, published in 1990 and now the most widely recommended formula for the general population. Older formulas such as Harris-Benedict tend to overestimate BMR for many modern adults, so Mifflin-St Jeor gives a more realistic starting point.
Why is BMR lower for women than for men?
On average women carry more body fat and less muscle than men of the same weight, and muscle tissue burns more energy at rest. The women's equation therefore subtracts 161 calories where the men's adds 5, reflecting that average difference in body composition.
How accurate is a BMR calculator?
For most healthy adults it lands within about 10 per cent of a laboratory measurement. Genetics, muscle mass, thyroid function and recent dieting can all move the true figure, so treat the result as a strong starting point and fine-tune it against your real weight changes.
Can I use my BMR to lose weight?
Yes, indirectly: multiply your BMR by your activity level to get your TDEE, then eat roughly 300–500 calories below that for steady loss. Never plan to eat far below your BMR itself for an extended period without professional advice, as that risks fatigue, muscle loss and nutrient shortfalls.