An online BMR calculator measures the Basal Metabolic Rate, i.e., the energy the organism consumes in a resting state. The calculator uses the Mifflin-St Jeor equation, taking into account weight, height, and age. The BMR result multiplied by the physical activity level determines the total daily energy expenditure. The coefficient ranges from 1.2 for a sedentary type to 1.9 for an extra active type.
Knowing your BMR allows you to set caloric intake according to your goal. To maintain weight, consume as many calories as you burn. For slow muscle mass gain, increase intake by 300–500 kcal a day; for faster gain, by 700–1,000 kcal. For weight loss, reduce intake by 500 kcal a day. Precise BMR is only provided by laboratory testing.
BMR or Basal Metabolic Rate, is a measure of the body’s energy expenditure at rest. The result of the BMR is a number that determines how many calories you need to take each day to keep the basic vital signs and body weight. Use our online BMR calculator for easier measurement of basal metabolic rate.
How to use BMR calculator?
Enter your age, sex, height and body weight in the form. The BMR calculator then calculates your BMR easily and quickly. The BMR score in the table also reflects your physical activity.
What is your BMR?
How does the BMR calculator work?
An easy way to calculate your BMR is to use 3 formulas created by statistics. The most accurate is Mifflin-St. Jeor formula, which we also used in our online BMR calculator. Their formula is as follows:
- For men: BMR = 10 x W + 6,25 x H – 5 x A + 5
- For women: BMR = 10 x W + 6,25 x H – 5 x A – 161
The values W, H and A mean:
- W (weight) is the body weight in kg
- H (height) is the height in cm
- A (age) is the age in years
To see how many calories you need per day, multiply your BMR by the physical activity coefficient listed in the table. The result will also reflect your physical activity.
| Sedentary type | Little or no movement | 1,2 |
| Lightly active type | Training 1 to 3 times a week | 1,375 |
| Moderately active type | Training 3 to 5 times a week | 1,55 |
| Very active type | Training 6 to 7 times a week | 1,725 |
| Extra active type | Very intensive daily training or physically demanding work | 1,9 |
BMR scores calculated using an online calculator or online formula may not accurately reflect your basal metabolic rate. The only way to get a 100% true BMR result is through laboratory testing.
Why is it good to know your personal BMR?
Once you know your BMR, you know exactly how many calories you burn when you rest. With BMR you can determine how many calories you need to absorb to gain muscle mass, lose fat or maintain weight. Simply put, knowing how many calories you consume and burn will make the way to your goal easier. How it works?
- Do you want to maintain your weight? Take as many calories as you burn.
- Is your goal to gain weight slowly and evenly? Increase the calorie intake by about 300 to 500 kcal per day.
- Is your goal to gain weight faster? Increase your calorie intake by about 700 to 1,000 kcal per day.
- Do you want to lose weight? Reduce calorie intake by about 500 kcal per day.
Frequently Asked Questions (FAQ)
The calculator uses the Mifflin-St. Jeor equation, which factors in body weight, height and age to calculate your basal metabolic rate (Basal Metabolic Rate – BMR) as accurately as possible. For men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161. The different constants reflect the fact that men have, on average, a 5 to 10% higher BMR than women. The average woman has a BMR of around 1,400 kcal and a man around 1,700 kcal.
Total daily energy expenditure (TDEE) represents all the calories the body burns over 24 hours, that is the basal metabolic rate (BMR) plus the energy spent on movement, exercise and digesting food. BMR reflects the energy for basic life functions at rest. You obtain your TDEE by multiplying your BMR by your physical activity level (PAL) in the range of 1.2–1.9.
The physical activity level (PAL) ranges from 1.2 for a sedentary lifestyle (office work with no sport) up to 1.9 for extremely active individuals (daily hard training + a physically demanding job). The most common mistake is overestimating your sporting activity: if you train for 1 hour at the gym but spend 30 minutes of that resting between sets, count only 30 minutes of active time.
The basal metabolic rate gradually slows down with age; after the age of 30, BMR drops by an average of 1–2% per decade, primarily due to the natural loss of muscle mass. Conversely, BMR rises with higher body weight, because the body needs more energy to maintain larger tissue. The key is to distinguish the composition of that weight. A kilogram of muscle burns 3 times more calories at rest than a kilogram of fat, which is why strength training after the age of 30 effectively curbs the decline in BMR.
You raise your basal metabolic rate primarily by gaining muscle mass, because muscle tissue burns considerably more calories at rest than fat, so regular strength training 2–3 times a week is one of the most effective tools. A sufficient protein intake (1.4–2.0 g/kg) also helps, as it has a high thermic effect and at the same time supports muscle growth. Conversely, avoid extreme diets below your BMR, which trigger adaptive thermogenesis and slow the metabolism down.
A “slow metabolism” in the lay sense is rarer than people think. If you suspect a medically slow metabolism, the cause is usually hypothyroidism (reduced thyroid function), Cushing’s syndrome or a prolonged extreme diet leading to adaptive thermogenesis. If you suspect this, see your GP or an endocrinologist, where simple TSH and fT4 blood tests will reveal any thyroid disorder.
Yes, a long-term calorie deficit really does lower BMR, because the body adapts to the lower energy intake and reduces its resting expenditure, which is called adaptive thermogenesis. The drop in BMR can reach 5 to 15%, and even more in extreme cases, as shown by a study of contestants on the reality show The Biggest Loser (Fothergill et al., 2016). To minimise this effect, choose a moderate deficit of up to 20% of TDEE, a sufficient protein intake, and include strength training, which protects muscle mass.
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