Calorie Deficit Calculator for Weight Loss
Use this calculator to estimate your Basal Metabolic Rate (BMR), Total Daily Energy Expenditure (TDEE), and the daily calorie target needed to achieve your desired weight loss.
Understanding Calorie Deficit for Weight Loss
A calorie deficit is the cornerstone of weight loss. It occurs when you consistently consume fewer calories than your body expends. When this happens, your body is forced to tap into its stored energy reserves, primarily fat, to make up the difference, leading to weight reduction.
How Your Body Uses Calories
Your body burns calories in three main ways:
- Basal Metabolic Rate (BMR): This is the number of calories your body needs to perform basic, life-sustaining functions at rest, such as breathing, circulation, cell production, and nutrient processing. It accounts for the largest portion of your daily calorie expenditure.
- Thermic Effect of Food (TEF): This is the energy your body uses to digest, absorb, and metabolize the food you eat. It typically accounts for about 10% of your total calorie expenditure.
- Activity Energy Expenditure (AEE): This includes all calories burned through physical activity, from structured exercise to non-exercise activity thermogenesis (NEAT) like walking, fidgeting, and standing.
Calculating Your BMR (Basal Metabolic Rate)
The calculator uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for estimating BMR:
- For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- For Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
This number represents the minimum calories your body needs to function if you were to do nothing but rest all day.
Calculating Your TDEE (Total Daily Energy Expenditure)
Your TDEE is your BMR multiplied by an activity factor, which accounts for your daily physical activity level. This gives you a more accurate estimate of the total calories you burn in a day.
- Sedentary (little or no exercise): BMR × 1.2
- Lightly Active (light exercise/sports 1-3 days/week): BMR × 1.375
- Moderately Active (moderate exercise/sports 3-5 days/week): BMR × 1.55
- Very Active (hard exercise/sports 6-7 days a week): BMR × 1.725
- Extra Active (very hard exercise/physical job/training twice a day): BMR × 1.9
Your TDEE is the number of calories you need to maintain your current weight.
Creating a Calorie Deficit for Weight Loss
To lose weight, you need to consume fewer calories than your TDEE. A common guideline is that a deficit of 3,500 calories equates to approximately 0.5 kg (1 pound) of fat loss. Therefore, to lose 0.5 kg per week, you would aim for a daily deficit of 500 calories (3500 calories / 7 days).
The calculator takes your desired weekly weight loss in kilograms and converts it into the necessary daily calorie deficit. For example, if you aim to lose 0.5 kg per week, the calculator will subtract approximately 500 calories from your TDEE to give you your daily calorie target.
Daily Calorie Target = TDEE – (Target Weekly Weight Loss in kg × 7700 / 7)
Note: 7700 calories is an approximate value for 1 kg of body fat.
Safe and Sustainable Weight Loss
While it might be tempting to create a very large calorie deficit for rapid weight loss, it's generally not recommended. A deficit that is too aggressive can lead to:
- Nutrient deficiencies
- Loss of muscle mass instead of fat
- Reduced energy levels and fatigue
- Metabolic adaptation, making future weight loss harder
- Increased risk of rebound weight gain
Most health professionals recommend a gradual weight loss of 0.25 kg to 1 kg (0.5 to 2 pounds) per week. This allows for sustainable fat loss while preserving muscle mass and ensuring adequate nutrient intake.
Beyond Calories: The Importance of Nutrition and Exercise
While a calorie deficit is essential, the quality of your calories matters significantly. Focus on a balanced diet rich in whole foods, lean proteins, healthy fats, and complex carbohydrates. Incorporate both strength training and cardiovascular exercise into your routine to support muscle retention, boost metabolism, and improve overall health.
Always consult with a healthcare professional or a registered dietitian before making significant changes to your diet or exercise routine, especially if you have underlying health conditions.