Calorie Deficit Calculator
Calculate exactly how many calories you need to lose weight. Understand your BMR, TDEE, and the perfect deficit for sustainable fat loss.
What Is a Calorie Deficit?
A calorie deficit happens when: Calories Burned > Calories Consumed. When this happens consistently, your body uses stored fat for energy, leading to weight loss.
Weight Loss Speed
Determined by the depth of your daily deficit.
Fat vs. Muscle
A proper deficit ensures you lose fat, not muscle mass.
Sustainability
Calculated deficits prevent extreme hunger and rebounding.
How to Calculate Calorie Deficit (Step-by-Step)
Calculate Your BMR (Basal Metabolic Rate)
We use the Mifflin-St Jeor Formula, the most accurate for adults:
Women: (10 × wt kg) + (6.25 × ht cm) − (5 × age) − 161
Calculate Your TDEE (Total Daily Energy Expenditure)
Multiply your BMR by your activity level multiplier:
| Activity Level | Multiplier |
|---|---|
| Sedentary | 1.2 |
| Light Exercise | 1.375 |
| Moderate Exercise | 1.55 |
| Very Active | 1.725 |
Apply the Calorie Deficit Formula
Calorie Deficit = Maintenance Calories (TDEE) − Target Intake
Safe Fat Loss Deficit Targets
| Daily Deficit | Expected Weekly Loss | Effort Level |
|---|---|---|
| 300 kcal | ~0.25 kg | Easy/Slow |
| 500 kcal | ~0.5 kg | Sustainable |
| 750 kcal | ~0.7 kg | Moderate |
| 1000 kcal | ~1 kg | Aggressive |
How Many Calories Deficit to Lose 1kg? 1 kg of fat ≈ 7,700 calories. To lose 1kg in a week, you'd need an 1,100 calorie daily deficit, which is aggressive and not ideal for most.
Lose Fat, Not Muscle
- Keep deficit moderate (300-500)
- Eat 1.6–2.2g of protein per kg
- Prioritize strength training
- Avoid crash dieting
Common Mistakes
- Eating too little: Leads to metabolic adaptation.
- Untracked oils/sauces: Hidden calories remove your deficit.
- Weekend overeating: Canceling out the weekday deficit.
- Overestimating exercise: Gym sessions burn less than you think.
Managing Weight Loss Plateaus
Most calculators don’t mention metabolic adaptation — but it matters. If you stop losing weight:
Realistic Expectations
A healthy fat loss rate is 0.5–1% of body weight per week. For an 80kg person, losing 0.4–0.8 kg per week is realistic and sustainable. Faster loss increases the risk of a weight rebound.
The "Free Calorie Deficit Calculator" Quality Standard:
An accurate tool must use the Mifflin-St Jeor formula, adjust for activity, allow for goal-based selection, and warn against cutting calories below your BMR.
Final Takeaway
Weight loss is not about starving. It’s about creating a controlled, sustainable calorie deficit. The best results happen when the deficit is moderate, protein is adequate, and progress is tracked weekly.
Curious about your hydration?
When dieting, water intake becomes even more critical for metabolic health.