Metabolic Rate Calculator

Metabolic rate describes how quickly the body burns energy. A particularly important figure is the basal metabolic rate (BMR). It indicates how many calories the body consumes per day when it is at rest and only maintains its vital functions.

This one number is the basis for all other values. Breathing, blood circulation, cell formation and repair, and maintaining body temperature - all these processes require energy, and in most people, the basal metabolism accounts for the largest part of daily calorie consumption.

BMR, RMR, TDEE: What these terms mean.

These three terms can be easily confused, so it's important to clarify the differences.

The basal metabolic rate is measured under strict conditions: complete rest, fasting and lying in a warm room. The resting energy expenditure (REE), on the other hand, is measured under less strict conditions and therefore usually slightly higher, often by about 10%.

In everyday life these two values are so similar that most calculators treat them as equivalent. The formula on this page estimates the energy expenditure in a resting state but is shown here as your BMR.

Total energy expenditure, also known as TDEE (Total Daily Energy Expenditure), provides a comprehensive overview. It combines the resting metabolic rate with the energy expended through activity, movement and digestion of food. The calculation is done by multiplying the basal metabolic rate (BMR) by an activity factor.

Here's how to use this calculator:

Enter your gender, age, height and weight and select the typical activity level for one week. The basal metabolic rate will be shown as a figure with daily total consumption next to it.

If you open the Metabolic Rate breakdown, you can see the same Resting Metabolic Rate in hours, watts and weeks. If you know your body fat percentage, you can switch to the Katch-McArdle formula. The comparison view allows you to see what each of the three formulas have calculated for your body.

Three formulas:

This calculator uses three different formulas. For average body types the results are very similar, but for extreme body types there can be differences. So choose the formula for which you can provide the most accurate inputs.

Mifflin-St Jeor (recommended)

This formula was published in 1990 and is more accurate than older formulas at reflecting the physical conditions of modern humans. As a result, most nutritionists prefer to use it today. It requires your weight, height, age, and gender.

In this formula w is the weight in kilograms, h is the height in centimeters and a is the age in years. For a man aged 30 with a weight of 80 kg and a height of 180 cm, the BMR would be about 1780 kcal per day.

Revised Harris-Benedict Formula

The Harris-Benedict formula was developed in 1919 and revised in 1984. It is a classic formula that produces results slightly higher than the Mifflin-St Jeor equation for many people.

Katch-McArdle formula

This formula calculates the value based on lean body mass and not total weight so it is probably most accurate if you know your body fat percentage. As it is based on lean body mass, gender is not directly taken into account.

The lean mass is calculated by multiplying the weight by the value that represents body fat percentage as a decimal and subtracting it from one. If the weight is 80 kg and the body fat percentage is 20%, then the lean mass is 64 kg, and the result of BMR calculation is about 1752 kcal.

Interpretation of metabolism as speed.

Because the BMR is actually a rate of energy expenditure, it can be expressed in several ways. The detailed breakdown shows this accordingly.

Dividing the daily value by 24 gives you the number of calories burned per hour at rest. Converted into watts this is the power required to keep your body functioning. This is because a large calorie is equal to 4,184 joules and there are 86,400 seconds in a day.

If the resting metabolic rate is 1,780 calories per day, it consumes about 74 calories per hour or about 86 watts. This is slightly more than the power of an old incandescent light bulb and your body maintains this output throughout the day.

Activity level

The activity factor increases the basal metabolic rate (BMR) to total daily energy expenditure. Please be honest here as most people often overestimate their actual activity level.

The table below shows the multipliers used in this calculator.

Factors that affect metabolism

Even if two people are exactly the same height, weight, age and gender, their rate of energy expenditure can be different. Some factors can account for much of this difference.

Muscle is a major factor that you can control. Muscle tissue performs metabolic activities and requires energy, so more muscle mass leads to a slightly higher basal metabolism. This is why strength training is often beneficial in the long term.

Height also plays a role. People with larger body frames have more tissue to maintain, so those who are heavier and taller will generally have higher BMRs as well.

Age and hormones have opposite effects. As we get older our resting metabolism gradually falls as muscle mass is lost. Thyroid hormones determine a large part of the basal metabolic rate, so problems with the thyroid can lead to changes in either direction.

How accurate is this calculator?

All the formulas used here provide estimates and not actual measurements. Even if two people have all of their data identical, their actual metabolism can vary due to genetic differences, muscle mass, and hormone levels. Only laboratory tests using a metabolic system can directly measure your metabolism.

Treat this as a reliable starting point. Plan for several weeks based on that amount, then observe your actual body response and adjust accordingly. Your own experience is the most accurate calculator available to you.

This calculator is for educational purposes only and does not constitute medical or nutritional advice. The estimated metabolic rates are given as a guide only and do not replace the judgment of a qualified professional. If you have any health issues such as thyroid problems, consult your doctor or nutritionist before making significant changes.

FAQs

What is metabolic turnover?

Metabolic rate refers to the speed at which your body burns energy. Basal metabolic rate is measured in a state of complete rest and includes basic life functions such as breathing, blood circulation, and organ function.

What is a Normal Metabolic Rate?

Metabolic rate varies widely based on body size. As a rough guide, many adult women will burn about 1400 calories per day while many adult men will burn between 1600 and 1800. The larger the body and the more muscle mass it has, the higher the number, with smaller bodies having lower numbers.

What is the difference between BMR, RMR and TDEE?

BMR (Basal Metabolic Rate) is the energy expenditure measured in a resting state under strictly controlled laboratory conditions while RMR (Resting Metabolic Rate) is an almost identical value that is measured under less strict conditions and usually comes out slightly higher. TDEE (Total Daily Energy Expenditure) is the sum of the resting energy expenditure plus all the energy expended through activity and digestion throughout the day.

How can we boost our metabolism?

The most effective way to do this is through strength training. Muscle tissue burns energy even when at rest. Adequate protein intake, regular activity throughout the day and avoiding extreme diets can also help prevent a slowing metabolism.

What formula is most accurate?

The Mifflin-St Jeor formula is the most reliable for the general population and is used as a standard here. When body fat percentage is known, the Katch-McArdle formula can be more accurate because it's based on lean mass rather than total weight.