Daily Calorie Needs Calculator
Use this calculator to estimate your daily calorie needs based on your age, gender, height, weight, and activity level. Understanding your caloric requirements is a fundamental step towards achieving your health and fitness goals, whether it's weight loss, maintenance, or gain.
Understanding Your Calorie Needs
Calorie counting is a method of tracking the energy you consume from food and beverages. The goal is to match your energy intake with your energy expenditure to achieve specific body composition goals. This calculator uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for estimating Basal Metabolic Rate (BMR).
Basal Metabolic Rate (BMR)
Your 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 amount of energy required to keep your body functioning if you were to do nothing but rest for 24 hours.
- 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
Total Daily Energy Expenditure (TDEE)
Your TDEE is the total number of calories your body burns in a 24-hour period, including your BMR and the calories expended through physical activity. The calculator multiplies your BMR by an activity factor to determine your TDEE:
- Sedentary: BMR × 1.2 (little to 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 a week)
- Extra Active: BMR × 1.9 (very hard exercise/physical job)
Adjusting for Your Goal
Once your TDEE is calculated, the calculator adjusts this number based on your chosen goal:
- Maintain Weight: No adjustment.
- Weight Loss: A calorie deficit is created (e.g., -500 calories for approximately 0.5 kg/week loss).
- Weight Gain: A calorie surplus is created (e.g., +500 calories for approximately 0.5 kg/week gain).
Remember that these are estimates. Individual metabolic rates can vary, and factors like body composition, genetics, and hormones can influence actual calorie needs. It's always recommended to consult with a healthcare professional or registered dietitian for personalized advice.
Tips for Effective Calorie Counting
- Be Accurate: Use a food scale for precise measurements, especially for calorie-dense foods.
- Track Everything: Don't forget drinks, sauces, and snacks.
- Read Labels: Pay attention to serving sizes and nutritional information.
- Be Consistent: Regular tracking provides the most useful data.
- Adjust as Needed: If you're not seeing the desired results, you may need to slightly adjust your calorie intake or activity level.
- Focus on Nutrients: While calories are important, prioritize nutrient-dense foods to ensure you're getting essential vitamins and minerals.
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function calculateCalories() {
var age = parseFloat(document.getElementById("age").value);
var heightCm = parseFloat(document.getElementById("heightCm").value);
var weightKg = parseFloat(document.getElementById("weightKg").value);
var genderMale = document.getElementById("genderMale").checked;
var activityFactor = parseFloat(document.getElementById("activityLevel").value);
var goalAdjustment = parseFloat(document.getElementById("calorieGoal").value);
var resultDiv = document.getElementById("result");
if (isNaN(age) || age <= 0 || isNaN(heightCm) || heightCm <= 0 || isNaN(weightKg) || weightKg <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for age, height, and weight.";
return;
}
var bmr;
if (genderMale) {
// Mifflin-St Jeor Equation for Men
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else {
// Mifflin-St Jeor Equation for Women
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
var tdee = bmr * activityFactor;
var dailyCalories = tdee + goalAdjustment;
resultDiv.innerHTML =
"Your Basal Metabolic Rate (BMR):
" + Math.round(bmr) + " calories/day" +
"Your Total Daily Energy Expenditure (TDEE):
" + Math.round(tdee) + " calories/day" +
"To achieve your goal, your estimated daily calorie intake is:
" + Math.round(dailyCalories) + " calories/day";
}