Metabolic Rate Calorie Calculator

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Metabolic Rate & Daily Calorie Calculator

Male Female
Sedentary (Little or no exercise) Lightly Active (Exercise 1-3 days/week) Moderately Active (Exercise 3-5 days/week) Active (Exercise 6-7 days/week) Very Active (Hard exercise & physical job)

Your Results

Basal Metabolic Rate (BMR)

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Calories/day at rest

Daily Maintenance (TDEE)

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Calories to maintain weight

Weight Loss (-0.5kg/week)

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Weight Gain (+0.5kg/week)

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function calculateMetabolism() { 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); if (isNaN(age) || isNaN(weight) || isNaN(height) || age <= 0 || weight <= 0 || height <= 0) { alert("Please enter valid positive numbers for all fields."); 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 loss = tdee – 500; var gain = tdee + 500; document.getElementById("bmr-output").innerHTML = Math.round(bmr).toLocaleString() + " kcal"; document.getElementById("tdee-output").innerHTML = Math.round(tdee).toLocaleString() + " kcal"; document.getElementById("loss-output").innerHTML = Math.round(loss).toLocaleString() + " kcal"; document.getElementById("gain-output").innerHTML = Math.round(gain).toLocaleString() + " kcal"; document.getElementById("results-box").style.display = "block"; }

Understanding Your Metabolic Rate

Whether you are looking to lose weight, build muscle, or simply maintain your current physique, understanding your metabolic rate is the first step toward reaching your health goals. Your body is a machine that burns fuel (calories) 24/7, even while you sleep.

What is Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain vital functions, such as breathing, heart rate, and cell production. It accounts for about 60% to 75% of your total daily energy expenditure. The calculator uses the Mifflin-St Jeor Equation, which is widely considered the most accurate formula for predicting metabolic rate in healthy adults.

TDEE: Total Daily Energy Expenditure

While BMR is what you burn doing nothing, TDEE is the total number of calories you burn daily after accounting for physical activity. This is the "maintenance" number. If you eat this amount, you will stay the same weight.

  • Calorie Deficit: Eating fewer than your TDEE (e.g., -500 calories) leads to weight loss.
  • Calorie Surplus: Eating more than your TDEE (e.g., +500 calories) leads to weight gain.

Realistic Example

Imagine a 30-year-old male who weighs 80 kg and is 180 cm tall.
1. His BMR would be approximately 1,790 calories.
2. If he has a desk job but exercises 3 times a week (Moderately Active – 1.55), his TDEE becomes roughly 2,775 calories.
3. To lose roughly 0.5kg of fat per week, he should aim for about 2,275 calories per day.

Factors That Influence Your Metabolism

Several factors can cause your metabolic rate to fluctuate:

  • Muscle Mass: Muscle tissue burns more calories than fat tissue, even at rest.
  • Age: Metabolism naturally slows down as we age due to loss of muscle mass and hormonal changes.
  • Genetics: Some individuals naturally have a slightly higher or lower BMR based on their genetic makeup.
  • Hormones: Thyroid issues or other hormonal imbalances can significantly impact how your body processes energy.

Note: While calculators provide a scientific estimate, they cannot account for individual variations in body composition (body fat percentage vs. muscle). For the most precise results, use this as a starting point and adjust your intake based on your progress over 2-3 weeks.

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