Calories to Lose Weight Calculator

Calories to Lose Weight Calculator

lbs kg
inches cm
Sedentary (little to no exercise) Lightly Active (light exercise/sports 1-3 days/week) Moderately Active (moderate exercise/sports 3-5 days/week) Very Active (hard exercise/sports 6-7 days/week) Extra Active (very hard exercise/physical job/training twice a day)
lbs/week kg/week
(Recommended: 0.5 – 2 lbs or 0.25 – 1 kg per week)

Your Calorie Recommendations:

Basal Metabolic Rate (BMR): calories/day

Total Daily Energy Expenditure (TDEE): calories/day

Target Daily Calorie Intake for Weight Loss: calories/day

function calculateCalories() { var currentWeight = parseFloat(document.getElementById('currentWeight').value); var weightUnit = document.getElementById('weightUnit').value; var heightValue = parseFloat(document.getElementById('heightValue').value); var heightUnit = document.getElementById('heightUnit').value; var age = parseInt(document.getElementById('age').value); var genderMale = document.getElementById('genderMale').checked; var activityLevel = parseFloat(document.getElementById('activityLevel').value); var weightLossGoal = parseFloat(document.getElementById('weightLossGoal').value); var goalUnit = document.getElementById('goalUnit').value; var resultDiv = document.getElementById('result'); var bmrResultSpan = document.getElementById('bmrResult'); var tdeeResultSpan = document.getElementById('tdeeResult'); var targetCaloriesResultSpan = document.getElementById('targetCaloriesResult'); var resultMessageSpan = document.getElementById('resultMessage'); resultMessageSpan.innerHTML = "; // Clear previous messages // Input validation if (isNaN(currentWeight) || currentWeight <= 0 || isNaN(heightValue) || heightValue <= 0 || isNaN(age) || age <= 0 || isNaN(activityLevel) || activityLevel <= 0 || isNaN(weightLossGoal) || weightLossGoal <= 0) { resultMessageSpan.innerHTML = 'Please enter valid positive numbers for all fields.'; resultDiv.style.display = 'block'; bmrResultSpan.innerHTML = ''; tdeeResultSpan.innerHTML = ''; targetCaloriesResultSpan.innerHTML = ''; return; } // Convert weight to kg var weightKg = (weightUnit === 'lbs') ? currentWeight / 2.20462 : currentWeight; // Convert height to cm var heightCm = (heightUnit === 'inches') ? heightValue * 2.54 : heightValue; // Convert weight loss goal to lbs/week for calorie deficit calculation var goalLbsPerWeek = (goalUnit === 'kg') ? weightLossGoal * 2.20462 : weightLossGoal; // Mifflin-St Jeor Equation for BMR var bmr; if (genderMale) { bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5; } else { // Female bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161; } // Calculate TDEE var tdee = bmr * activityLevel; // Calculate daily calorie deficit (1 lb fat = 3500 calories) var dailyCalorieDeficit = (goalLbsPerWeek * 3500) / 7; // Calculate target daily calorie intake var targetCalories = tdee – dailyCalorieDeficit; // Display results bmrResultSpan.innerHTML = Math.round(bmr); tdeeResultSpan.innerHTML = Math.round(tdee); targetCaloriesResultSpan.innerHTML = Math.round(targetCalories); resultDiv.style.display = 'block'; // Add warnings for very low calorie intake if (targetCalories < 1200) { resultMessageSpan.innerHTML = 'Warning: A daily intake below 1200 calories is generally not recommended without medical supervision. Please consult a healthcare professional.'; } else if (genderMale && targetCalories 2 && goalUnit === 'lbs') { resultMessageSpan.innerHTML = 'Note: Losing more than 2 lbs per week is often not sustainable or healthy. Consider a more moderate goal.'; } else if (weightLossGoal > 1 && goalUnit === 'kg') { resultMessageSpan.innerHTML = 'Note: Losing more than 1 kg per week is often not sustainable or healthy. Consider a more moderate goal.'; } }

Understanding Your Calorie Needs for Weight Loss

Losing weight effectively often comes down to creating a calorie deficit – consuming fewer calories than your body burns. Our Calories to Lose Weight Calculator helps you estimate your daily calorie target to achieve your weight loss goals in a healthy and sustainable way.

How It Works: The Science Behind the Numbers

This calculator uses established scientific principles to estimate your calorie needs:

1. 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, cell production, and nutrient processing. It's the minimum amount of energy your body needs to simply exist. Our 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

Factors like age, gender, height, and weight all influence your BMR.

2. Total Daily Energy Expenditure (TDEE)

Your BMR only accounts for calories burned at rest. Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, including your BMR and the calories burned through physical activity. To calculate TDEE, your BMR is multiplied by an activity factor:

  • Sedentary (little to 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/week): BMR × 1.725
  • Extra Active (very hard exercise/physical job/training twice a day): BMR × 1.9

This TDEE is the number of calories you need to maintain your current weight.

3. Calorie Deficit for Weight Loss

To lose weight, you need to consume fewer calories than your TDEE. This creates a "calorie deficit." It's widely accepted that a deficit of 3,500 calories is roughly equivalent to one pound of fat. Therefore, to lose:

  • 1 pound per week: You need a daily deficit of 500 calories (3500 calories / 7 days).
  • 2 pounds per week: You need a daily deficit of 1000 calories (7000 calories / 7 days).

Our calculator takes your desired weekly weight loss goal and subtracts the corresponding daily calorie deficit from your TDEE to give you your target daily calorie intake.

Healthy and Sustainable Weight Loss

While it might be tempting to aim for rapid weight loss, a gradual and consistent approach is generally healthier and more sustainable. Most health professionals recommend aiming for a weight loss of 1 to 2 pounds (0.5 to 1 kg) per week. This allows your body to adapt, helps preserve muscle mass, and makes it easier to maintain your new weight long-term.

Extremely low-calorie diets (below 1200 calories for women or 1500 calories for men) can be detrimental to your health, leading to nutrient deficiencies, muscle loss, and metabolic slowdown. Always consult with a doctor or a registered dietitian before making significant changes to your diet, especially if you have underlying health conditions.

Using the Calculator: A Step-by-Step Example

Let's say we have a 30-year-old male, 5'8″ (68 inches) tall, weighing 180 lbs, who is moderately active and wants to lose 1 lb per week.

  1. Input Current Weight: 180 lbs
  2. Input Height: 68 inches
  3. Input Age: 30 years
  4. Select Gender: Male
  5. Select Activity Level: Moderately Active (factor 1.55)
  6. Input Weekly Weight Loss Goal: 1 lb/week
  7. Click "Calculate Calories"

The calculator would then perform the following (approximate) steps:

  • Convert Units: 180 lbs ≈ 81.65 kg; 68 inches ≈ 172.72 cm
  • Calculate BMR: (10 × 81.65) + (6.25 × 172.72) – (5 × 30) + 5 ≈ 816.5 + 1079.5 – 150 + 5 ≈ 1751 calories
  • Calculate TDEE: 1751 × 1.55 ≈ 2714 calories
  • Calculate Daily Calorie Deficit: (1 lb × 3500 calories/lb) / 7 days ≈ 500 calories/day
  • Calculate Target Daily Calorie Intake: 2714 – 500 ≈ 2214 calories/day

This means our example individual would aim for approximately 2214 calories per day to lose 1 pound per week.

Important Considerations

While this calculator provides a valuable estimate, remember that individual results can vary. Factors like body composition, genetics, hormonal balance, and specific types of exercise can all influence your actual calorie burn and weight loss rate. Use this tool as a starting point and adjust your intake based on your progress and how you feel. Always prioritize nutrient-dense foods and a balanced diet.

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