How to use the BMR & Daily Calorie Calculator
- Choose your sex as used in the formula.
- Enter your age, height in centimetres and weight in kilograms.
- Choose the activity level that matches a typical week for you. Be honest, because most people overestimate it.
- Read your BMR, the calories to maintain weight, and the figures for gradual loss or gain.
Formula used
Mifflin-St Jeor: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or − 161 for women. Maintenance calories = BMR × activity factor.
Worked example
Here is the BMR & Daily Calorie Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Sex | Male |
| Age | 30 years |
| Height | 175 cm |
| Weight | 70 kg |
| Activity level | Moderate exercise 3–5 days a week |
| Result | |
| BMR (kcal per day) | 1,649 |
| Calories to maintain weight (kcal per day) | 2,556 |
| For gradual weight loss (kcal per day) | 2,056 |
| For gradual weight gain (kcal per day) | 3,056 |
Calories by activity level
Estimated maintenance calories for the default profile at each activity level.
| Activity level | Calories per day |
|---|---|
| Little or no exercise | 1,979 kcal |
| Light exercise 1–3 days a week | 2,267 kcal |
| Moderate exercise 3–5 days a week | 2,556 kcal |
| Hard exercise 6–7 days a week | 2,844 kcal |
| Very hard exercise or physical job | 3,133 kcal |
The formula behind the result
This calculator uses the Mifflin-St Jeor equation, which is widely used by dietitians. For men, BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women, the last term is −161 instead of +5.
For a 30-year-old man who is 175 cm tall and weighs 70 kg, BMR = 700 + 1,093.75 − 150 + 5 = 1,648.75 calories a day. The same measurements for a woman give 1,482.75.
From BMR to daily calories
Maintenance calories equal BMR multiplied by an activity factor: 1.2 for little or no exercise, 1.375 for light exercise, 1.55 for moderate exercise, 1.725 for hard exercise and 1.9 for very hard exercise or a physical job. For the example man the figures are 1,979, 2,267, 2,556, 2,844 and 3,133 calories.
The activity multiplier is the biggest source of error. An office worker who walks 20 minutes a day belongs in the light category, even if they feel busy.
Using the loss and gain targets
The calculator shows a figure 500 calories below maintenance for gradual weight loss and 500 above for gradual weight gain. A deficit of about 500 calories a day is often cited as leading to roughly half a kilogram of loss a week, but real results vary a lot between people and slow down over time.
Very low calorie intakes can be unsafe, and some people should not diet without medical supervision, including children, pregnant women and people with certain health conditions. If you want to lose or gain a lot of weight, speak to a doctor or a registered dietitian.
Limits of the estimate
Formulas estimate the average person. Muscle burns more energy than fat, so two people of the same weight can have different needs. Age, genetics, hormones, illness and medicines also play a part. Treat the result as a starting point and adjust based on how your weight changes over a few weeks.
This is general information and not medical advice. It is not suitable for diagnosing or treating any condition.
Frequently asked questions
What is BMR?
BMR is the number of calories your body uses at complete rest to keep basic functions running.
Which formula does this use?
The Mifflin-St Jeor equation, which uses weight, height, age and sex.
How many calories should I eat to lose weight?
A modest deficit below maintenance, such as 300 to 500 calories, is a common starting point. Confirm what suits you with a doctor or dietitian.
Should I eat below my BMR?
Eating far below BMR for long periods can be harmful. Do not do it without medical advice.
Which activity level should I choose?
Choose the level that matches an average week, and if you are unsure, pick the lower one.
Is this accurate for athletes or older adults?
It may be less accurate, because muscle mass and age change energy needs. Use it as a rough guide.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.