Daily Calorie Needs Calculator
The Number That Anchors Every Diet Plan
Before any diet can target a surplus or a deficit, it needs a baseline: how many calories your body burns in an average day, doing exactly what you normally do. That baseline is total daily energy expenditure, and it's built from two pieces — your resting metabolic rate, and a multiplier for how active you are on top of it. This calculator computes both.
The Formula
Female: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
Daily Calorie Needs = BMR × Activity Multiplier
This is the Mifflin-St Jeor equation, published in 1990 and widely regarded as more accurate than the older Harris-Benedict formula it replaced in most clinical and fitness settings. BMR alone is what your body would burn lying still all day; the activity multiplier scales that up for however much you actually move.
Activity Multipliers and What They Assume
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise | ×1.2 |
| Lightly active | Light exercise 1–3 days/week | ×1.375 |
| Moderately active | Moderate exercise 3–5 days/week | ×1.55 |
| Very active | Hard exercise 6–7 days/week | ×1.725 |
| Extra active | Very hard exercise and a physical job | ×1.9 |
Worked Example
For a 30-year-old man, 75 kg, 178 cm tall: BMR = (10×75) + (6.25×178) − (5×30) + 5 = 1,717.5 calories/day. Applying each multiplier:
| Activity level | Daily calories |
|---|---|
| Sedentary | 2,061.0 kcal |
| Lightly active | 2,361.6 kcal |
| Moderately active | 2,662.1 kcal |
| Very active | 2,962.7 kcal |
| Extra active | 3,263.2 kcal |
Computed directly with the formula above. The gap between sedentary and extra active for the same person is over 1,200 calories — activity level matters as much as body size in this equation.
Where This Number Gets Used
- Maintenance baseline — the starting point before deciding on a surplus (for muscle or weight gain) or a deficit (for weight loss).
- Tracking accuracy — comparing logged food intake against this figure is more informative than a generic "2,000 calorie" reference that ignores your size and activity.
- Adjusting over time — as weight or activity level changes, recalculating keeps the baseline current rather than stale.
How to Use This Calculator
- Choose Metric (kg/cm) or Imperial (lb/in) units.
- Select Male or Female.
- Enter your Age, Weight, and Height.
- Select your Activity level from the dropdown.
- Select Calculate for your BMR and total daily calorie needs.
Related Calculations
To build a specific weight-loss target from this baseline, use the Calorie Deficit Calculator. Once you know your calorie target, the Macronutrient Ratio Calculator breaks it into protein, carb, and fat grams.