Calorie Needs and Basal Metabolic Rate: Where the Number Comes From
Basal metabolic rate, resting energy expenditure and PAL explained: how daily calorie needs are calculated, which formulas exist and how accurate the result is.
Health & Body3 linked calculatorsReading time: 6 min.
Guidance, not a diagnosis
This article explains reference values and where they come from. It does not replace a medical examination or advice. Different values often apply if you have symptoms, are pregnant, for children and for pre-existing conditions: in that case, talk to your doctor.
How many calories does a person need per day? The answer has two parts: the energy used at rest and what movement costs on top. Both can only be estimated. This guide shows how the estimate is made and where its limits are.
Key takeaways
- Daily needs are the resting rate times the PAL value, a number for how physically active your day is.
- For an office job with no exercise, the German Nutrition Society (DGE) gives a PAL value of about 1.4.
- Different formulas give slightly different results for the same person; the result is a guideline, not a measurement.
- According to the DGE, people of similar weight can differ by up to 1,900 kcal a day depending on job and leisure activity.
Basal rate, resting rate, total expenditure
Basal metabolic rate is the energy the body needs at complete rest for breathing, circulation and metabolism. It is measured under strict conditions: in the morning after about eight hours of sleep, roughly twelve hours after the last meal, at a comfortable room temperature.
Resting energy expenditure is measured under less strict conditions and, according to the DGE, is about 10% above the basal rate because it already includes part of the energy used for digestion. In everyday use both terms are often treated the same.
Total energy expenditure is the whole day's use: resting rate plus the energy for work, getting around, housework and exercise. It equals the calorie intake at which weight stays the same.
Two formulas for the resting rate
Without a measuring device, the resting rate is estimated from weight, age, sex and sometimes height. Two widely used formulas:
- DGE formula: women (0.047 × weight in kg − 0.01452 × age in years + 3.21) × 239; men add 1.009 inside the brackets. Result in kcal per day.
- Mifflin-St Jeor formula (1990, developed in adults): 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men and − 161 for women. Our calorie calculator uses this formula.
For a woman weighing 60 kg aged 40, the DGE formula gives about 1,302 kcal. Mifflin-St Jeor, with a height of 165 cm (example value), gives about 1,270 kcal, a good 2% less. Both are estimates; neither is wrong.
Why the formulas differ
Each formula was developed in a different group of people. Muscle mass, health and ambient temperature change actual expenditure, and no formula captures them. Small differences between calculators are therefore normal.
The PAL value: how active your day is
PAL stands for physical activity level. It tells you how far your daily expenditure lies above the resting rate. The DGE classifies it by job and leisure time:
| PAL value | Typical day (per DGE) |
|---|---|
| 1.2 to 1.3 | exclusively sitting or lying, such as bedridden people |
| 1.4 to 1.5 | exclusively seated work with little or no strenuous leisure activity, such as office work |
| 1.6 to 1.7 | mostly seated with some walking or standing, such as lab work or studying |
| 1.8 to 1.9 | mostly walking and standing work, such as retail, restaurants or skilled trades |
| 2.0 to 2.4 | physically demanding work or very active leisure, such as construction or competitive sport |
If you exercise or do other strenuous activities four to five times a week for 30 to 60 minutes, the DGE says to add 0.3.
From resting rate to daily needs
The calculation itself is simple: resting rate × PAL value = daily needs.
Example with the DGE formula: the woman from the section above works in an office and does no exercise (PAL 1.4). Her daily needs are about 1,302 × 1.4 ≈ 1,823 kcal. If she trains four to five times a week, her PAL rises to 1.7 and her needs to about 2,214 kcal.
Calculate your calorie needs
Using weight, height, age and a DGE activity level, with an optional exercise add-on.
How much a single workout burns is estimated by the exercise calorie calculator.
How much energy nutrients contain
Energy comes from carbohydrates, fat, protein and alcohol. Their energy content per gram according to the DGE:
| Nutrient (1 g) | kcal | kJ |
|---|---|---|
| Carbohydrates | 4 | 17 |
| Fat | 9 | 37 |
| Protein | 4 | 17 |
| Alcohol | 7 | 29 |
Food labels often give energy in kilojoules: 1 kcal equals 4.184 kJ.
Calorie needs and weight loss
To lose weight, you eat a little less than your total expenditure over time. How large the deficit should be depends on your starting point. As a guide, our calorie calculator shows a value 20% below your needs; this is an assumption, not medical advice. With severe overweight, existing conditions, during pregnancy and breastfeeding, a weight-loss plan belongs under medical supervision.
How long until your target weight?
The weight loss duration calculator estimates the time from calorie needs and deficit.
Frequently asked questions about calorie needs
What is the difference between basal metabolic rate and calorie needs?
How accurate is a calorie calculator?
How do I account for exercise?
Does the calculation apply to children and teenagers?
Sources
Every figure in this article comes from these primary sources or from the linked calculators, which are based on the same sources.
- German Nutrition Society (DGE): FAQ on energy intake (resting energy expenditure, PAL, energy content) (accessed September 30, 2026)
- German Nutrition Society (DGE): reference values for energy (accessed September 30, 2026)
- Mifflin MD et al.: A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241–247 (accessed September 30, 2026)
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