Calorie and BMR calculator

Formula

How it works

The Mifflin–St Jeor equation estimates the calories you burn at rest from weight, height, age and sex. Multiplying by an activity factor (1.2 to 1.9) estimates your total daily use.

Worked example

The same calculation with the default values:

• Sex Female
• Age 35 years
• Weight 70 kg
• Height 170 cm
• Activity level Light (1–3 days a week)

1. BMR = 10 × 70 + 6.25 × 170 − 5 × 35 + (-161) = 1,426.5 kcal
2. calories = 1,426.5 × 1.375 = 1,961.4375 kcal/day

Result: Basal metabolic rate: 1,426.5 kcal/day · Calories to maintain weight: 1,961.4375 kcal/day

Common mistakes

• Choosing a higher activity level than actually sustained - most people overestimate their own activity level, which inflates the "maintenance" calorie figure.
• Using the BMR number itself (resting metabolism) as a daily calorie target instead of the activity-adjusted maintenance figure, which is almost always higher.
• Treating the maintenance number as exact to the calorie for weight-loss or weight-gain planning - it is a reasonable starting estimate to adjust from based on real-world results over a few weeks, not a precise prescription.