Your daily calorie need is your basal metabolic rate (BMR) multiplied by your physical activity level (PAL). This calculator uses the BMR equations published by the FAO/WHO/UNU expert consultation on human energy requirements and its PAL bands: 1.40 to 1.69 for sedentary or light lifestyles, 1.70 to 1.99 for active ones and 2.00 to 2.40 for vigorous ones[1].
The NHS explains what calories are and how many most adults need in its guide to understanding calories.
How the calorie calculator works
Step one is your basal metabolic rate, the energy your body uses at rest to breathe, circulate blood and keep warm. The FAO/WHO/UNU report gives one equation for each sex and age band, based on body weight[1]:
| Age | Men (kcal a day) | Women (kcal a day) |
|---|---|---|
| 18 to 29 | 15.057 x weight in kg + 692.2 | 14.818 x weight in kg + 486.6 |
| 30 to 59 | 11.472 x weight in kg + 873.1 | 8.126 x weight in kg + 845.6 |
| 60 and over | 11.711 x weight in kg + 587.7 | 9.082 x weight in kg + 658.5 |
Step two multiplies BMR by your physical activity level. The report groups lifestyles into three bands[1]:
| Lifestyle | PAL range | Typical day |
|---|---|---|
| Sedentary or light activity | 1.40 to 1.69 | Office work, driving, little planned exercise |
| Active or moderately active | 1.70 to 1.99 | On your feet much of the day, or an hour of exercise most days |
| Vigorous or vigorously active | 2.00 to 2.40 | Heavy manual work or hard training every day |
Because each band is a range, the calculator gives your result as a range too. A 35-year-old woman weighing 70 kg has a BMR of about 1,414 kcal. With a sedentary or light lifestyle her daily need works out at roughly 1,980 to 2,390 kcal.
Why we show a range
Equations describe groups of people, and any single person can sit above or below the average. Showing the full band for your activity level is more honest than a precise-looking figure. Use the middle of the range as a starting point, then watch what your weight does over a few weeks and adjust.
Using the result to lose, gain or keep weight
To keep your weight steady, eat around your estimated need. To lose weight, most people do best with a moderate, steady deficit they can live with, built from foods that keep them full: vegetables, fruit, whole grains, pulses and enough protein. To gain weight or muscle, eat a little above your need and pair it with strength training.
Very low-calorie diets, weight loss during pregnancy, eating disorders, diabetes treated with insulin and weight-loss medicines all need professional supervision. A dietitian can set targets that protect your muscle, your nutrients and your relationship with food.
Other calculators to use with this one
- Protein calculator: how much protein a day at your weight.
- Fibre target: the WHO daily fibre goal.
- BMI calculator: where your weight sits for your height.
Book a video, phone or in-person session with a professional from our network. Your result can be attached so you do not start from scratch.
More free tools
- BMI calculator
- Protein calculator
- Water intake calculator
- Fibre target
- Waist-to-height ratio
- Which professional do I need?
- Healthy eating check
- Compare two countries
Frequently asked questions
How many calories do I need a day?
It depends on your sex, age, weight and activity. The calculator multiplies your BMR from the FAO/WHO/UNU equations by the PAL band for your lifestyle and shows the range[1].
Which equation does this calculator use?
The adult BMR equations in chapter 5 of the FAO/WHO/UNU report on human energy requirements, which predict BMR from body weight for each sex and age band[1].
Why is my result a range?
Because each lifestyle band spans a range of physical activity levels, from 1.40 to 1.69 for sedentary or light lifestyles, for example[1]. A range is more honest than a single figure.
Is this calculator suitable in pregnancy?
No. Energy needs change in pregnancy and breastfeeding. Ask your midwife, doctor or a dietitian.
Does the calculator store my data?
No. Everything runs in your browser unless you choose to share the result when you book.
Sources and citations
Every figure on this page was read on the publisher's own page. Where a country or body does not publish a figure we say so instead of estimating.
- FAO / WHO / UNU, Human energy requirements: report of a joint FAO/WHO/UNU expert consultation (chapter 5, adults) (2004)
