Calories Calculator to Lose Weight

Daily Calorie Needs for Weight Loss Calculator

Use this calculator to estimate your daily calorie needs to achieve your weight loss goals. It uses the Mifflin-St Jeor equation to determine your Basal Metabolic Rate (BMR) and then adjusts for your activity level to find your Total Daily Energy Expenditure (TDEE). Finally, it calculates the calorie deficit required for your target weight loss.

Male Female





Sedentary (little or 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 a week) Extra Active (very hard exercise/physical job)

function calculateCalories() { var age = parseFloat(document.getElementById('age').value); var gender = document.getElementById('gender').value; var heightCm = parseFloat(document.getElementById('heightCm').value); var weightKg = parseFloat(document.getElementById('weightKg').value); var activityLevel = document.getElementById('activityLevel').value; var targetWeightLossKg = parseFloat(document.getElementById('targetWeightLossKg').value); if (isNaN(age) || isNaN(heightCm) || isNaN(weightKg) || isNaN(targetWeightLossKg) || age <= 0 || heightCm <= 0 || weightKg <= 0 || targetWeightLossKg <= 0) { document.getElementById('result').innerHTML = 'Please enter valid positive numbers for all fields.'; return; } var bmr; // Mifflin-St Jeor Equation if (gender === 'male') { bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5; } else { // female bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161; } var tdee; switch (activityLevel) { case 'sedentary': tdee = bmr * 1.2; break; case 'lightlyActive': tdee = bmr * 1.375; break; case 'moderatelyActive': tdee = bmr * 1.55; break; case 'veryActive': tdee = bmr * 1.725; break; case 'extraActive': tdee = bmr * 1.9; break; default: tdee = bmr * 1.2; // Default to sedentary if something goes wrong } // 1 kg of fat is approximately 7700 calories var dailyDeficit = (targetWeightLossKg * 7700) / 7; var targetCalories = tdee – dailyDeficit; if (targetCalories < 1200 && gender === 'female') { document.getElementById('result').innerHTML = 'Calculated target calories are very low (' + targetCalories.toFixed(0) + ' kcal). For women, consuming less than 1200 calories per day is generally not recommended without medical supervision. Please adjust your target weight loss or consult a healthcare professional.'; return; } if (targetCalories < 1500 && gender === 'male') { document.getElementById('result').innerHTML = 'Calculated target calories are very low (' + targetCalories.toFixed(0) + ' kcal). For men, consuming less than 1500 calories per day is generally not recommended without medical supervision. Please adjust your target weight loss or consult a healthcare professional.'; return; } var resultHtml = '

Your Calorie Needs:

'; resultHtml += 'Your Basal Metabolic Rate (BMR): ' + bmr.toFixed(0) + ' kcal/day (calories your body burns at rest).'; resultHtml += 'Your Total Daily Energy Expenditure (TDEE): ' + tdee.toFixed(0) + ' kcal/day (calories your body burns with activity).'; resultHtml += 'To lose ' + targetWeightLossKg.toFixed(1) + ' kg per week, you need a daily calorie deficit of approximately ' + dailyDeficit.toFixed(0) + ' kcal.'; resultHtml += 'Your estimated daily calorie intake for weight loss: ' + targetCalories.toFixed(0) + ' kcal/day.'; resultHtml += 'Note: These are estimates. Individual results may vary. Always consult a healthcare professional or registered dietitian before making significant changes to your diet or exercise routine.'; document.getElementById('result').innerHTML = resultHtml; }

Understanding Your Calorie Needs for Weight Loss

Losing weight fundamentally comes down to creating a calorie deficit, meaning you consume fewer calories than your body burns. This calculator helps you estimate the number of calories you should aim for daily to achieve your weight loss goals safely and effectively.

Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions while at rest. This includes breathing, circulation, cell production, nutrient processing, and organ function. It's the minimum amount of energy required to keep you alive. Factors like age, gender, height, and current weight significantly influence your BMR.

Total Daily Energy Expenditure (TDEE)

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. This is why your activity level is a crucial input for this calculator. The more active you are, the higher your TDEE will be.

• Sedentary: Little or 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 a week.
• Extra Active: Very hard exercise/physical job.

Creating a Calorie Deficit for Weight Loss

To lose weight, you need to consume fewer calories than your TDEE. This forces your body to use stored energy (fat) for fuel. A common guideline is that a deficit of approximately 7,700 calories is needed to lose 1 kilogram of body fat. Therefore, to lose 0.5 kg (about 1 pound) per week, you would need a daily deficit of about 550 calories (7700 calories / 7 days / 2 = 550).

Our calculator takes your desired weekly weight loss in kilograms and calculates the necessary daily calorie deficit to achieve that goal, then subtracts it from your TDEE to give you a target daily calorie intake.

Important Considerations for Healthy Weight Loss

• Sustainable Goals: Aim for a gradual weight loss of 0.5 to 1 kg (1-2 pounds) per week. Rapid weight loss can be unhealthy and often unsustainable.
• Nutrient Density: Focus on consuming nutrient-dense foods like lean proteins, whole grains, fruits, and vegetables. Even with a calorie deficit, it's vital to get adequate vitamins and minerals.
• Hydration: Drink plenty of water throughout the day. It can help with satiety and overall bodily functions.
• Exercise: While diet is key for weight loss, regular physical activity helps burn more calories, build muscle (which boosts metabolism), and improve overall health.
• Listen to Your Body: Pay attention to hunger and fullness cues. Avoid extreme calorie restriction, which can lead to nutrient deficiencies and rebound weight gain.
• Consult a Professional: Always consult a doctor or a registered dietitian before starting any new diet or exercise program, especially if you have underlying health conditions. They can provide personalized advice and ensure your plan is safe and appropriate for you.

This calculator provides an estimate to guide you. Individual metabolic rates and responses to diet and exercise can vary. Use this tool as a starting point for your weight loss journey, combined with a balanced diet and regular physical activity.