Scientifically speaking, one kilocalorie is 1,000 calories. However, the term calorie in lay English has become so loosely used with the same meaning as kilocalorie, that the two terms have virtually merged. In other words, in most cases, a calorie and kilocalorie have the same meaning.
A kilocalorie is the amount of energy required to raise the temperature of 1 kilogram of water from 15° to 16° Celsius (centigrade) at one atmosphere.
A "small calorie" refers to the traditional scientific term of calorie, meaning one-thousandth of a kilocalorie.
Internationally, most nations talk about food energy in kJ (kilojoules). 1 kcal (kilocalorie) = 4.184 kJ.
In this article, the term "calorie" means the same as "kilocalorie" or "kcal".
Calorie intake calculator
The Harris-Benedict equation, also known as the Harris-Benedict principle, is used to estimate what a person's BMR (basal metabolic rate) and daily requirements are.
Your BMR total is multiplied by another number which represents your level of physical activity. The resulting number is your recommended daily calorie intake in order to keep your body weight where it is.
This equation has some limitations. It does not take into account varying levels of muscle mass to fat mass ratios - a very muscular person needs more calories, even when resting.
- Male adults 66.5 + (13.75 x kg body weight) + (5.003 x height in cm) - (6.755 x age) = BMR 66 + ( 6.23 x pounds body weight) + ( 12.7 x height in inches ) - ( 6.76 x age) = BMR
- Female adults 55.1 + (9.563 x kg body weight) + (1.850 x height in cm) - (4.676 x age) = BMR 655 + (4.35 x kg body weight) + (4.7 x height in inches) - (4.7 x age) = BMR
Daily calorie calculators
You can use our BMR calculators below to work out your BMR and daily calorie recommendation. One calculator uses metric measurements and the other uses imperial measurements - the choice is yours.
2) Imperial BMR Calculator
Your daily calorie requirement
To work out a figure for your daily calorie requirement, we apply levels of physical activity to the equation as per the guide below. If you have entered information into the calculator above, you'll see your personal calculations:
- Sedentary lifestyle - if you do very little or no exercise at all Your daily calorie requirement is BMR x 1.2.
- Slightly active lifestyle - light exercise between once and three times per week Your daily calorie requirement is BMR x 1.375.
- Moderately active lifestyle - if you do moderate exercise three to five days per week Your daily calorie requirement is BMR x 1.55.
- Active lifestyle - if you do intensive/heavy exercise six to seven times per week Your daily calorie requirement is BMR x 1.725.
- Very active lifestyle - if you do very heavy/intensive exercise twice a day (extra heavy workouts Your daily calorie requirement is BMR x 1.9.