Most Accurate Calorie Deficit Calculator
Use this calculator to determine your Basal Metabolic Rate (BMR), Total Daily Energy Expenditure (TDEE), and the ideal daily calorie intake to achieve your weight loss goals. This calculator uses the widely accepted Mifflin-St Jeor equation for BMR and factors in your activity level for a more precise estimate.
Understanding Your Calorie Deficit
A calorie deficit is the foundation of weight loss. It occurs when you consistently consume fewer calories than your body expends. Your body then turns to stored fat for energy, leading to a reduction in body weight. This calculator helps you pinpoint the precise numbers needed to achieve a sustainable and healthy calorie deficit.
Basal Metabolic Rate (BMR)
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain basic life-sustaining functions like breathing, circulation, and cell production. It's the minimum energy required to keep you alive. Our calculator uses the Mifflin-St Jeor equation, which is considered one of the most accurate BMR formulas for the general population:
- 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
For example, a 30-year-old female, 170 cm tall, weighing 70 kg would have a BMR of (10 * 70) + (6.25 * 170) – (5 * 30) – 161 = 700 + 1062.5 – 150 – 161 = 1451.5 kcal.
Total Daily Energy Expenditure (TDEE)
While BMR tells you how many calories you burn at rest, your Total Daily Energy Expenditure (TDEE) accounts for all the calories you burn throughout the day, including physical activity. To calculate TDEE, your BMR is multiplied by an activity factor:
- Sedentary: BMR × 1.2 (little or no exercise)
- Lightly Active: BMR × 1.375 (light exercise/sports 1-3 days/week)
- Moderately Active: BMR × 1.55 (moderate exercise/sports 3-5 days/week)
- Very Active: BMR × 1.725 (hard exercise/sports 6-7 days/week)
- Extra Active: BMR × 1.9 (very hard exercise/physical job/training twice a day)
Continuing our example, if the 30-year-old female with a BMR of 1451.5 kcal is Moderately Active, her TDEE would be 1451.5 * 1.55 = 2249.8 kcal.
Calculating Your Calorie Deficit for Weight Loss
Once you have your TDEE, creating a calorie deficit is straightforward. You simply subtract your desired deficit from your TDEE to find your target daily calorie intake for weight loss. A common and healthy deficit for sustainable weight loss is 500 calories per day, which typically leads to about 0.5 kg (1 pound) of fat loss per week (since 3500 calories equals approximately 0.5 kg of fat).
Using our example: If the female's TDEE is 2249.8 kcal and she aims for a 500 kcal deficit, her target daily calorie intake for weight loss would be 2249.8 – 500 = 1749.8 kcal. This would result in an estimated weekly weight loss of 0.5 kg.
Important Considerations
While this calculator provides a highly accurate estimate, individual results can vary due to metabolism, body composition, and other factors. It's crucial to ensure your calorie deficit is not too extreme, as very low-calorie diets can be detrimental to health and difficult to sustain. Always aim for a gradual and consistent weight loss of 0.5 to 1 kg (1-2 pounds) per week. Consult with a healthcare professional or registered dietitian for personalized advice, especially if you have underlying health conditions.