Calories
";steps+="Weight: "+weight+" lbs ("+weightKg.toFixed(1)+" kg)
";steps+="Height: "+ft+"'"+inches+"\" ("+heightCm.toFixed(1)+" cm)
";steps+="BMR Calculation: "+Math.round(bmr)+" calories/day
";steps+="Step 2: Calculate TDEE (Maintenance)
";steps+="TDEE = BMR × Activity Multiplier ("+activity+")
";steps+="TDEE = "+Math.round(tdee)+" calories/day
";steps+="Step 3: Apply Deficit
";steps+="Target = "+Math.round(tdee)+" – "+goal+"
";steps+="Result = "+Math.round(target)+" calories/day"+warning;document.getElementById('stepsOutput').innerHTML=steps;document.getElementById('stepsOutput').style.display='block';}else{document.getElementById('stepsOutput').style.display='none';}}
Calculator Use
The calorie deficit calculator is a professional-grade tool designed to help you determine exactly how many calories you should consume daily to reach your weight loss goals. By understanding the relationship between your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE), you can create a sustainable plan for fat loss.
To get the most accurate results, ensure you provide precise measurements for the following inputs:
- Gender and Age
- Metabolism naturally varies by biological sex and age. Men generally have higher lean muscle mass, and BMR typically decreases as we age.
- Weight and Height
- These determine your body mass. Larger bodies require more energy to maintain basic functions.
- Activity Level
- This represents the "multiplier" effect of your lifestyle. Be honest here—most people overestimate their daily activity level.
- Weight Loss Goal
- Choose between 0.5 lb to 2 lbs per week. A 500-calorie daily deficit is the standard for losing one pound of body fat per week.
How It Works
Weight loss is governed by the First Law of Thermodynamics: Energy cannot be created or destroyed, only transformed. When you consume fewer calories than your body burns, it is forced to use stored energy (fat) to make up the difference. This calculator uses the Mifflin-St Jeor Equation, widely considered the most accurate formula for estimating metabolic rate.
Target Calories = (BMR × Activity Multiplier) – Goal Deficit
- BMR: The energy your body burns at total rest just to keep your heart beating and lungs breathing.
- TDEE: Your BMR plus the calories burned through walking, working, and exercising.
- Deficit: The amount subtracted from TDEE to trigger weight loss.
Calculation Example
Example: A 35-year-old female, weighing 160 lbs, standing 5'6″ tall, who works an office job but exercises 3 days a week (Moderately Active).
Step-by-step solution:
- Convert to Metric: 160 lbs = 72.6 kg; 5'6″ = 167.6 cm.
- Calculate BMR: (10 × 72.6) + (6.25 × 167.6) – (5 × 35) – 161 = 1,437.5 kcal.
- Calculate TDEE: 1,437.5 × 1.55 (Activity) = 2,228 kcal/day.
- Apply Deficit: 2,228 – 500 (for 1 lb/week loss) = 1,728 kcal.
- Final Result: Target intake is 1,728 calories per day.
Common Questions
What is a safe calorie deficit?
Most health experts recommend a deficit of 500 to 1,000 calories per day, which leads to a safe weight loss of 1 to 2 pounds per week. Dropping below 1,200 calories for women or 1,500 for men should only be done under medical supervision to avoid nutrient deficiencies and metabolic adaptation.
Why am I not losing weight in a deficit?
If the calorie deficit calculator suggests a number but you aren't seeing progress, common reasons include "hidden" calories (cooking oils, drinks), underestimating portion sizes, or a decrease in non-exercise activity (NEAT) because your body is trying to conserve energy. Consistency over weeks, not days, is the key to seeing results.
Does the type of food matter in a deficit?
For weight loss alone, the total calorie number is the primary driver. However, for body composition (losing fat instead of muscle), protein intake is critical. A high-protein diet while in a deficit helps preserve lean muscle mass and keeps you feeling full longer.