How to work out your daily calories
- Choose Metric or US units and your Sex.
- Enter your Age, height and weight, then pick the Activity level closest to a normal week.
- Read the calories a day that keep your weight steady, your resting rate (BMR) and the targets for losing or gaining weight.
How the numbers are worked out
Your resting rate comes from the Mifflin-St Jeor equation, with weight in kilograms, height in centimetres and age in years:
- Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161
- Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5
For the default example, a 35-year-old woman who is 168 cm tall and weighs 68 kg: 680 + 1,050 − 175 − 161 = 1,394 calories at rest. Moderate exercise multiplies that by 1.55, which gives 2,160.7. Every figure is rounded to the nearest 10, so the tool shows 1,390 and 2,160. Her loss targets come out at 1,890 and 1,610 calories a day.
If you choose US units, the calculator converts feet, inches and pounds to metric before using the same formula.
Picking your activity level
| Activity | Multiplier |
|---|---|
| Little or no exercise | 1.2 |
| Light: 1 to 3 days a week | 1.375 |
| Moderate: 3 to 5 days a week | 1.55 |
| Hard: 6 to 7 days a week | 1.725 |
| Very hard or a physical job | 1.9 |
Count a typical week, not your best one. A desk job with three gym sessions is light to moderate. Someone on their feet all day in a warehouse or on a building site can fairly pick the top level. If you’re between two, choose the lower one and see how your weight responds.
The calories you need also change as you go. Weigh less and your TDEE drops, so run the numbers again after a noticeable change in weight.