Calorie Calculator — Daily Calorie & Macro Needs
What Are Calories?
Calories are units of energy your body uses for everything it does — breathing, digestion, circulation and physical activity. Every food and drink you consume provides calories, which your body converts into the energy needed to function and move.
How This Calculator Works
This calculator works in two steps. First, it estimates your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest. Then, it multiplies that by an activity factor to estimate your Total Daily Energy Expenditure (TDEE) — the calories you burn in a typical day, including activity.
Formulas Used
| Formula | Men | Women |
|---|---|---|
| Mifflin-St Jeor (primary) | 10W + 6.25H − 5A + 5 | 10W + 6.25H − 5A − 161 |
| Harris-Benedict (comparison) | 88.362 + 13.397W + 4.799H − 5.677A | 447.593 + 9.247W + 3.098H − 4.330A |
W = weight in kg, H = height in cm, A = age in years. Mifflin-St Jeor is generally considered more accurate for most modern populations and is used as the primary formula above; Harris-Benedict is shown for comparison.
Activity Level Multipliers
| 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 intense training or physical job | 1.9 |
Example Calculation
For a 25-year-old male, 70 kg, 175 cm, moderately active:
- BMR (Mifflin-St Jeor) = 10×70 + 6.25×175 − 5×25 + 5 ≈ 1,674 kcal
- TDEE = 1,674 × 1.55 ≈ 2,595 kcal/day to maintain current weight
Understanding Macros
Calories come from three macronutrients — protein, carbohydrates and fat — each with a different energy density:
- Protein: 4 calories per gram — supports muscle repair and growth
- Carbohydrates: 4 calories per gram — the body's primary energy source
- Fat: 9 calories per gram — supports hormone production and nutrient absorption
This calculator splits your maintenance calories across these three based on the macro style you choose — balanced, high-protein, or low-carb — giving you a practical daily gram target for each.
Why Knowing Your Calorie Needs Matters
- Gives you a realistic, personalised starting point for weight goals
- Helps prevent both overeating and under-eating
- Supports more effective diet and meal planning
- Makes tracking progress toward fitness goals more meaningful
Limitations to Keep in Mind
- These formulas estimate average needs — individual metabolism can vary by 10–15% either way
- Don't account for medical conditions that affect metabolism
- Muscle mass, sleep quality and stress levels also influence real-world energy needs
- Best used as a starting point to adjust from, based on how your actual weight responds over 2–3 weeks
