What it is and what it is for
Your body burns energy even at rest to keep breathing, stay warm and run its vital functions. That is your basal metabolic rate. Multiply it by a factor for your activity level and you get an estimate of the calories you burn on a normal day, which is what you need to maintain your weight.
The calculator uses the Mifflin-St Jeor equation, one of the most widely accepted for healthy adults. It is an estimate: two people with the same data can burn different amounts. Use it as a starting point and adjust it based on how your weight moves over several weeks.
How to use it, step by step
- Choose your sex and enter your age in completed years.
- Enter your weight in kilograms and your height in centimetres.
- Pick the activity level that best describes your typical week, and be honest.
- Press Calculate to see your basal rate and maintenance calories.
- Use the loss and gain figures as a reference and readjust every two or three weeks.
Worked example
A 35-year-old woman, 65 kg, 165 cm with light activity has a basal rate of about 1,345 kcal and maintenance of about 1,850 kcal a day. To lose around half a kilo a week the reference drops to about 1,350 kcal, and to gain weight gradually it rises to about 2,150 kcal.
Frequently asked questions
Why does the weight-loss figure never go below 1,200 kcal?
Because below that level it is hard to meet nutrient needs without professional supervision.
Is it valid during pregnancy or with medical conditions?
No. Needs differ in those cases and should be guided by a healthcare professional.
How accurate is the estimate?
It has a margin of error of around 10%. Track your weight over several weeks to fine-tune it.
Should I count exercise calories separately?
No. The activity factor already includes them; counting them twice would lead you to overeat.