How many calories do you need a day?
Enter your sex, age, height, weight and how active you are. I calculate your basal metabolic rate and the calories to keep your weight with the Mifflin–St Jeor equation, the same one the Calorko app uses.
kcal a day to keep your weight
The equation is an estimate: your real burn can be 10% higher or lower. Watch your weight for two to three weeks and adjust.
The result is an estimate, not medical advice or a diagnosis. The calculator is for adults (18+). If you're pregnant, breastfeeding or have a condition that affects your diet (such as diabetes or kidney disease), make your plan with a doctor.
How it works
First I calculate your basal metabolic rate (BMR) with the Mifflin–St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men or − 161 for women. If you prefer not to say, I use the midpoint (− 78).
Then I multiply the BMR by an activity factor. The result estimates how many calories you burn on an average day, which is what you need to eat to keep your weight the same.
Activity factors
| Activity | Factor |
|---|---|
| Mostly sitting · Desk job, little movement | 1.2 |
| Lightly active · Walks or workouts 1–3 times a week | 1.375 |
| Moderately active · Workouts 3–5 times a week | 1.55 |
| Very active · Workouts 6–7 times a week | 1.725 |
| Extremely active · Physical job or two workouts a day | 1.9 |
Example
Woman, 35, 165 cm, 65 kg, moderately active: BMR = 10 × 65 + 6.25 × 165 − 5 × 35 − 161 = 1,345 kcal. Times 1.55, that is about 2,085 kcal a day to keep her weight.
Frequently asked questions
What is basal metabolic rate?
The energy your body uses at rest: breathing, heart and brain, keeping warm. For most people it is more than half of what they burn in a day.
How accurate is the Mifflin–St Jeor equation?
For most adults it is closer to real burn than older equations, but it is still an estimate: for one person it can be off by 10% or more. The best check is your weight after two to three weeks.
Which activity level should I pick?
If you're not sure, pick the lower one. People overestimate how active they are more often than not, and an hour of training doesn't make the rest of the day active.
Do I have to eat exactly this much every day?
No. It is an average: if your weekly average stays close to it, your weight stays about the same, even when days differ.