Quick Answer
Enter your sex, age, height and weight in the calculator below to get your Basal Metabolic Rate (BMR) in seconds.
BMR is the calories your body burns at complete rest, just to keep your organs running. The tool then multiplies that number by five activity factors so you can see your total daily energy needs (TDEE).
For most adults, BMR accounts for 60-75% of all calories burned in a day.
BMR Calculator
Mifflin-St Jeor resting burn plus all five activity levels.
See exactly how many calories you burn at rest, plus your daily needs across every activity level.
What is BMR?
BMR stands for Basal Metabolic Rate. Think of it as your "coma calories", the energy your body would need if you laid in bed all day without moving a muscle. It covers breathing, blood circulation, cell production and nutrient processing.
Knowing your BMR is the first step in any sensible nutrition plan. Once you know what your body burns at rest, you can layer activity on top to find your true daily target.
BMR vs TDEE: what's the difference?
BMR is the minimum survival energy. TDEE (Total Daily Energy Expenditure) is BMR plus everything else you do, walking, working, training, even digesting food.
Rule of thumb: never eat below your BMR for long stretches without medical supervision.
Activity multipliers (BMR to TDEE)
| Lifestyle | Multiplier | Description |
|---|---|---|
| Sedentary | BMR × 1.2 | Desk job, little to no exercise |
| Lightly Active | BMR × 1.375 | Light exercise 1-3 days/week |
| Moderately Active | BMR × 1.55 | Moderate exercise 3-5 days/week |
| Very Active | BMR × 1.725 | Hard exercise 6-7 days/week |
| Super Active | BMR × 1.9 | Physical job or 2 training sessions a day |
What affects your BMR?
Three big levers move the BMR number: muscle mass, age and genetics.
- Muscle mass: Muscle is more metabolically active than fat. More lean tissue means a higher resting burn.
- Age: BMR drops by roughly 2-5% per decade after age 20, mostly due to gradual muscle loss.
- Genetics: Thyroid activity and other hormonal factors set the baseline you're working with.
Typical BMR ranges
| Group | Average BMR (kcal/day) |
|---|---|
| Adult women | 1,200-1,500 |
| Adult men | 1,600-1,800 |
How to increase your BMR
- Lift weights. Building muscle is the most reliable long-term way to raise your resting burn.
- Eat enough protein. Protein has the highest thermic effect and protects lean mass during fat loss.
- Sleep properly. Chronic sleep loss measurably slows metabolic function and disrupts appetite hormones.
Formula and methodology
The calculator uses the Mifflin-St Jeor equation, which is widely considered the most accurate predictor of resting metabolic rate for modern adults.
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
- Katch-McArdle (advanced): 370 + (21.6 × Lean Body Mass in kg). Best for athletes who know their body fat percentage.
Frequently asked questions
What is BMR and why does it matter?
BMR is the number of calories your body needs to perform basic, life-sustaining functions at complete rest. It's the foundation of every calorie target, whether you want to lose fat, maintain or gain muscle.
How is BMR different for men and women?
Men generally carry more lean muscle, so their resting burn is higher. In the Mifflin-St Jeor formula, men add 5 to the total while women subtract 161.
Is BMR the same as RMR?
Not exactly. BMR is measured under strict laboratory conditions (fasted, fully rested). RMR is less strict and usually comes out about 10% higher. In everyday use, the two are often used interchangeably.
Should I eat my BMR calories to lose weight?
Eating at BMR creates a deficit equal to your physical activity, so it can drive fat loss. But sitting below BMR for weeks at a time is a poor strategy, it tanks energy, hormones and training quality.
Does muscle really burn more calories than fat?
Yes. One pound of muscle burns roughly 6-7 calories per day at rest, while a pound of fat burns about 2. The difference compounds over years of training.
Is "starvation mode" real?
It is, technically called adaptive thermogenesis. Aggressive, prolonged calorie cuts cause the body to lower its metabolic rate to conserve energy. Slow, moderate deficits avoid this trap.
Does eating more often boost metabolism?
Mostly a myth. The thermic effect of food depends on total calories and macro composition, not meal frequency.
Why does BMR fall with age?
Sarcopenia, natural muscle loss, is the main driver. Resistance training and adequate protein blunt or even reverse this decline.
Does drinking cold water raise BMR?
Technically yes, but the effect is tiny. Maybe 10-20 extra calories a day, which won't change your physique.
Does being overweight increase BMR?
Yes. A larger body needs more energy to maintain itself, so BMR scales with weight.
What about thyroid issues?
Hypothyroidism lowers BMR and can make weight gain easier. If your real-world results don't match the numbers, ask your doctor for a thyroid panel.
What to do with your BMR number
Once you know your BMR and TDEE, the rest of nutrition planning falls into place: pick a goal, set a sensible deficit or surplus, and break the calories into protein, carbs and fat.
Pair this tool with my Calorie Calculator for fat-loss and gain targets, and the Macro Split Calculator to turn calories into food choices.
Medical disclaimer
This calculator and article are for general educational and wellness purposes only. They are not a substitute for professional medical advice, diagnosis or treatment. Results are estimates based on population formulas and do not account for every individual factor.
If you are pregnant or breastfeeding, under 18, over 65, an athlete, recovering from illness or surgery, or living with a chronic condition (diabetes, heart, kidney, thyroid, eating disorder), speak to a qualified healthcare professional before changing your diet, exercise or hydration habits based on these numbers.
See the full site-wide Disclaimer & Notice for the complete terms that apply to every calculator and tool on dmbio.
