How to Calculate Calorie Needs
Published January 10, 2026 · 8 min read
Your daily calorie needs depend on your Basal Metabolic Rate (BMR) and how active you are. This guide shows you the exact formulas to find maintenance calories, then adjust for weight loss, muscle gain, or recomposition. You will see real examples, macro splits, and common mistakes to avoid.
BMR, TDEE, and Activity Multipliers
BMR (Basal Metabolic Rate) is the calories your body needs at rest. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to estimate your daily needs.
- Sedentary: little/no exercise (×1.2)
- Lightly active: 1-3 days/week (×1.375)
- Moderately active: 3-5 days/week (×1.55)
- Very active: 6-7 days/week (×1.725)
- Extra active: hard training + physical job (×1.9)
BMR Formulas (Mifflin-St Jeor)
BMR (men) = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5
BMR (women) = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161
Alternate: Harris-Benedict is similar; Mifflin-St Jeor is generally more accurate for modern populations.
Step-by-Step: Calculate Your Daily Calories
- Calculate BMR. Use Mifflin-St Jeor with your weight (kg), height (cm), and age.
- Pick an activity factor. Match your weekly training and job activity to the multipliers above.
- Find maintenance calories. Multiply BMR by your activity factor to get TDEE.
- Adjust for your goal. Subtract 10-20% for weight loss; add 5-15% for slow muscle gain.
- Set macros (optional). Aim for 1.6-2.2 g/kg protein, 20-35% calories from fat, rest from carbs.
Calorie Need Examples
Example 1: Weight Loss (Woman)
Scenario:
Age 30, 65 kg, 165 cm, lightly active (×1.375)
Step 1: BMR
BMR ≈ 10×65 + 6.25×165 - 5×30 -161 = 1384 kcal
Step 2: TDEE
TDEE ≈ 1384 × 1.375 = 1902 kcal
Step 3: Weight-loss target
10-20% deficit → ~1520-1710 kcal/day
Recommended target: ~1,600 kcal/day
Example 2: Maintenance (Man)
Scenario:
Age 35, 80 kg, 180 cm, moderately active (×1.55)
Step 1: BMR
BMR ≈ 10×80 + 6.25×180 - 5×35 + 5 = 1755 kcal
Step 2: TDEE
TDEE ≈ 1755 × 1.55 = 2710 kcal
Maintenance target: ~2,700 kcal/day
Example 3: Lean Bulk (Man)
Scenario:
Age 28, 72 kg, 178 cm, very active (×1.725)
Step 1: BMR
BMR ≈ 10×72 + 6.25×178 - 5×28 + 5 = 1712 kcal
Step 2: TDEE
TDEE ≈ 1712 × 1.725 = 2952 kcal
Step 3: Surplus for lean gain
+10% → ~3250 kcal/day
Lean bulk target: ~3,250 kcal/day
For minimal fat gain, keep weekly weight gain ~0.25-0.5 lb (0.1-0.25 kg).
Setting Macros
- Protein: 1.6-2.2 g per kg of body weight (or 0.7-1.0 g per lb) to preserve/ build muscle.
- Fat: 20-35% of total calories to support hormones and absorption of fat-soluble vitamins.
- Carbs: Fill remaining calories; prioritize whole grains, fruits, vegetables, and fiber.
Common Calorie Calculation Mistakes
- Using goal weight in the BMR formula instead of current weight.
- Overestimating activity level, leading to stalled fat loss.
- Creating too large a deficit (>25%), risking muscle loss and adherence issues.
- Ignoring protein intake; low protein makes deficits harder to sustain.
- Not accounting for liquid calories (coffee creamers, alcohol).
- Relying on wearable calorie numbers, which can be off by 20-40%.
Frequently Asked Questions
Which BMR formula is best?
Mifflin-St Jeor is widely accepted for accuracy; Harris-Benedict is an alternative. For athletes with high muscle mass, use the calculator and adjust based on 2-3 weeks of tracking results.
How big should a calorie deficit be?
A 10-20% deficit is sustainable for most people. Larger deficits can accelerate loss but increase risk of muscle loss and burnout.
How do I adjust for plateaus?
First verify tracking accuracy and steps/activity. If weight has stalled 2-3 weeks, reduce calories by ~5-10% or add activity.
Do I eat back exercise calories?
If your activity factor already includes typical training, you usually do not need to add calories back. For unusually long or intense sessions, add a portion (e.g., 50-70%) of verified burn.
Should I change calories on rest days?
You can keep calories steady and adjust carbs around workouts, or use small rest-day reductions. Consistency often improves adherence.
How do I set protein, fat, and carbs?
Start with protein 1.6-2.2 g/kg, fat 20-35% of calories, and fill the rest with carbs. Tweak based on energy, performance, and satiety.
Can I build muscle in a small deficit?
New lifters and detrained athletes often can; intermediates and advanced lifters usually need maintenance or slight surplus for muscle gain.
How often should I recalc my calories?
Recalculate when body weight changes ~5% or when activity levels shift meaningfully (job change, new training block).