Calorie Calculator for Weight Loss

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calorie calculator for weight loss
Maintain WeightMild Weight Loss (0.5 lb / 0.25 kg per week)Standard Weight Loss (1 lb / 0.5 kg per week)Extreme Weight Loss (2 lb / 1 kg per week)
MaleFemale
Sedentary (office job)Lightly Active (1-3 days/week)Moderately Active (3-5 days/week)Very Active (6-7 days/week)Extra Active (physical job)
Daily Calorie Results:
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Calories per day to reach your goal
function calculateCalorie(){var gender=document.getElementById('gender').value;var age=parseFloat(document.getElementById('age').value);var weight=parseFloat(document.getElementById('weight').value);var height=parseFloat(document.getElementById('height').value);var activity=parseFloat(document.getElementById('activity').value);var deficit=parseFloat(document.getElementById('goal').value);var showSteps=document.getElementById('steps').checked;if(isNaN(age)||isNaN(weight)||isNaN(height)){alert('Please enter valid numeric values for age, weight, and height.');return;}var bmr=0;if(gender==='male'){bmr=(10*weight)+(6.25*height)-(5*age)+5;}else{bmr=(10*weight)+(6.25*height)-(5*age)-161;}var tdee=bmr*activity;var target=tdee-deficit;if(target<1200 && gender==='female'){alert('Warning: Calorie intake is very low. Consult a doctor.');}if(target<1500 && gender==='male'){alert('Warning: Calorie intake is very low. Consult a doctor.');}document.getElementById('finalResult').innerHTML=Math.round(target)+' Calories';var details=document.getElementById('extraDetails');if(showSteps){details.style.display='block';details.innerHTML='Step 1: Basal Metabolic Rate (BMR): '+Math.round(bmr)+' cal/day
Step 2: Total Daily Energy Expenditure (TDEE): '+Math.round(tdee)+' cal/day
Step 3: Applied Deficit: -'+deficit+' cal/day

Note: This calculation uses the Mifflin-St Jeor Equation, considered the most accurate for healthy adults.';}else{details.style.display='none';}}

Calculator Use

The calorie calculator for weight loss is a professional tool designed to help you determine exactly how many calories you should consume daily to reach your specific body weight goals. Unlike generic estimates, this calculator uses your personal biological data—including age, gender, current weight, and height—combined with your physical activity levels to create a customized energy profile.

To get the most accurate result, follow these steps:

Gender and Age
Metabolic rates vary by biological sex and naturally decrease as we age. Enter your current age in years.
Height and Weight
Use metric measurements (cm and kg) for the calculation. Your current mass and height determine your Basal Metabolic Rate (BMR).
Activity Level
Select the option that best describes your weekly exercise routine. Overestimating activity is a common mistake; if you have a desk job and walk occasionally, "Lightly Active" is usually most appropriate.

How It Works

This calorie calculator for weight loss utilizes the Mifflin-St Jeor Equation. Published in 1990, this formula remains the gold standard in clinical settings for estimating human energy requirements. The process involves two primary calculations:

BMR (Men) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5
BMR (Women) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161

Once your BMR (the calories you burn just staying alive) is calculated, we apply an activity multiplier to find your Total Daily Energy Expenditure (TDEE):

  • Sedentary: TDEE = BMR × 1.2
  • Lightly Active: TDEE = BMR × 1.375
  • Moderately Active: TDEE = BMR × 1.55
  • Very Active: TDEE = BMR × 1.725
  • Extra Active: TDEE = BMR × 1.9

Finally, to achieve weight loss, a caloric deficit is applied. Since roughly 3,500 calories equal 1 pound of body fat, a daily deficit of 500 calories results in approximately 1 pound of weight loss per week.

Calculation Example

Example: Let's calculate the needs for a 35-year-old male, weighing 90kg, standing 180cm tall, who is moderately active and wants to lose 1lb per week.

Step-by-step solution:

  1. Calculate BMR: (10 × 90) + (6.25 × 180) – (5 × 35) + 5 = 900 + 1125 – 175 + 5 = 1,855 calories.
  2. Calculate TDEE: 1,855 × 1.55 (Moderate Activity) = 2,875 calories (Maintenance).
  3. Apply Deficit: 2,875 – 500 = 2,375 calories.
  4. Result: To lose 1 lb per week, this individual should consume approximately 2,375 calories daily.

Common Questions

How accurate is this calorie calculator for weight loss?

While the Mifflin-St Jeor equation is highly accurate for most people, it does not account for muscle mass vs. body fat ratio. Highly muscular individuals may have a higher BMR than calculated, while those with higher body fat percentages might have a slightly lower BMR.

What is the minimum safe calorie intake?

Generally, it is not recommended for women to drop below 1,200 calories per day or for men to drop below 1,500 calories per day without medical supervision. Consuming too few calories can lead to nutrient deficiencies and metabolic slowdown.

Why am I not losing weight even if I follow the calculator?

Common reasons include underestimating food intake (not tracking sauces, oils, or snacks), overestimating activity levels, or water retention. Ensure you are weighing your food for the most accurate tracking when using the calorie calculator for weight loss results.

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