My Basal Metabolic Rate Calculator

My Basal Metabolic Rate (BMR) Calculator .bmr-calculator-wrapper { max-width: 800px; margin: 0 auto; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; color: #333; line-height: 1.6; } .bmr-calc-box { background: #f9f9f9; border: 1px solid #e0e0e0; border-radius: 8px; padding: 25px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); margin-bottom: 30px; } .bmr-calc-title { text-align: center; margin-bottom: 20px; color: #2c3e50; font-size: 24px; font-weight: 700; } .bmr-form-group { margin-bottom: 15px; } .bmr-form-group label { display: block; margin-bottom: 5px; font-weight: 600; color: #444; } .bmr-radio-group { display: flex; gap: 20px; margin-bottom: 15px; } .bmr-radio-label { font-weight: normal; cursor: pointer; display: flex; align-items: center; } .bmr-radio-label input { margin-right: 8px; } .bmr-input { width: 100%; padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; box-sizing: border-box; } .bmr-row { display: flex; gap: 15px; } .bmr-col { flex: 1; } .bmr-btn { width: 100%; background-color: #27ae60; color: white; border: none; padding: 12px; font-size: 18px; font-weight: bold; border-radius: 4px; cursor: pointer; transition: background-color 0.3s; margin-top: 10px; } .bmr-btn:hover { background-color: #219150; } .bmr-results { margin-top: 25px; padding: 20px; background-color: #fff; border: 1px solid #ddd; border-radius: 6px; display: none; } .bmr-result-item { margin-bottom: 15px; text-align: center; } .bmr-main-value { font-size: 32px; color: #27ae60; font-weight: 800; display: block; } .bmr-sub-value { font-size: 14px; color: #666; } .tdee-table { width: 100%; border-collapse: collapse; margin-top: 15px; font-size: 14px; } .tdee-table th, .tdee-table td { padding: 8px; border-bottom: 1px solid #eee; text-align: left; } .tdee-table th { background-color: #f2f2f2; font-weight: 600; } .tdee-row-highlight { background-color: #e8f5e9; font-weight: bold; } .bmr-content { margin-top: 40px; } .bmr-content h2 { color: #2c3e50; margin-top: 25px; border-bottom: 2px solid #eee; padding-bottom: 10px; } .bmr-content p { margin-bottom: 15px; } .bmr-content ul { margin-bottom: 15px; padding-left: 20px; } .bmr-content li { margin-bottom: 8px; } /* Hide Imperial/Metric fields based on selection */ .imperial-field { display: none; }
My Basal Metabolic Rate Calculator
Sedentary (little or no exercise) Lightly active (exercise 1-3 days/week) Moderately active (exercise 3-5 days/week) Very active (exercise 6-7 days/week) Extra active (very hard exercise/physical job)
Your Basal Metabolic Rate (BMR) 0 Calories/day
Total Daily Energy Expenditure (TDEE) 0 Calories/day

(Calories needed to maintain current weight)


Daily Calorie Needs Based on Activity:
Activity Level Calories

What is My Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) represents the minimum number of calories your body needs to perform basic life-sustaining functions while at rest. These functions include breathing, circulation, nutrient processing, cell production, and temperature regulation.

Think of BMR as the amount of electricity your body would burn if you stayed in bed all day without moving. Even when you are completely inactive, your body burns calories just to keep you alive. This calculator helps you estimate that baseline energy expenditure.

How is BMR Calculated?

This calculator uses the Mifflin-St Jeor Equation, which is widely considered the most accurate standard for estimating BMR in clinical settings. The formulas differ slightly for men and women:

  • Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
  • Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

While the equation provides a solid estimate, actual metabolic rates can vary based on factors like genetics, hormone levels, and body composition (muscle mass vs. fat mass).

BMR vs. TDEE: What's the Difference?

While BMR measures energy at complete rest, your Total Daily Energy Expenditure (TDEE) accounts for how active you are throughout the day. TDEE is calculated by multiplying your BMR by an activity factor.

Knowing your TDEE is crucial for dietary planning:

  • To Maintain Weight: Consume calories equal to your TDEE.
  • To Lose Weight: Consume fewer calories than your TDEE (a caloric deficit).
  • To Gain Weight: Consume more calories than your TDEE (a caloric surplus).

Factors That Influence Your Metabolism

Several variables impact your personal BMR result:

  1. Muscle Mass: Muscle tissue burns more calories at rest than fat tissue. Increasing muscle mass through strength training can raise your BMR.
  2. Age: Metabolism naturally slows down as you age, often due to a loss of muscle tissue and hormonal changes.
  3. Body Size: Larger bodies generally have more metabolizing tissue and therefore a higher BMR.
  4. Gender: Men typically have less body fat and more muscle mass than women of the same age and weight, resulting in a higher BMR.

How to Use These Results

Once you have calculated your BMR and TDEE using the tool above, you can plan your nutrition accordingly. A common approach for sustainable weight loss is to subtract 500 calories from your TDEE, aiming for a loss of approximately 1 pound (0.45 kg) per week.

Note: This calculator provides an estimate. For precise metabolic measurements, consult with a healthcare provider or dietitian.

function toggleBmrUnits() { var isMetric = document.getElementById('unitMetric').checked; var metricFields = document.getElementsByClassName('metric-field'); var imperialFields = document.getElementsByClassName('imperial-field'); if (isMetric) { for (var i = 0; i < metricFields.length; i++) metricFields[i].style.display = 'block'; for (var i = 0; i < imperialFields.length; i++) imperialFields[i].style.display = 'none'; } else { for (var i = 0; i < metricFields.length; i++) metricFields[i].style.display = 'none'; for (var i = 0; i < imperialFields.length; i++) imperialFields[i].style.display = 'block'; } } function calculateBMR() { // Inputs var age = parseFloat(document.getElementById('bmrAge').value); var isMale = document.getElementById('genderMale').checked; var activityMultiplier = parseFloat(document.getElementById('bmrActivity').value); var isMetric = document.getElementById('unitMetric').checked; var weightKg = 0; var heightCm = 0; // Validation & Conversion if (isNaN(age) || age < 1) { alert("Please enter a valid age."); return; } if (isMetric) { var w = parseFloat(document.getElementById('bmrWeightKg').value); var h = parseFloat(document.getElementById('bmrHeightCm').value); if (isNaN(w) || isNaN(h) || w <= 0 || h <= 0) { alert("Please enter valid weight and height."); return; } weightKg = w; heightCm = h; } else { var wLbs = parseFloat(document.getElementById('bmrWeightLbs').value); var hFt = parseFloat(document.getElementById('bmrHeightFt').value); var hIn = parseFloat(document.getElementById('bmrHeightIn').value); // Handle if inches are empty but feet are not, or vice versa if (isNaN(hFt)) hFt = 0; if (isNaN(hIn)) hIn = 0; if (isNaN(wLbs) || (hFt === 0 && hIn === 0) || wLbs <= 0) { alert("Please enter valid weight and height."); return; } // Convert to Metric // 1 lb = 0.453592 kg // 1 ft = 30.48 cm, 1 in = 2.54 cm weightKg = wLbs * 0.453592; heightCm = (hFt * 30.48) + (hIn * 2.54); } // Mifflin-St Jeor Equation // Men: (10 × weight) + (6.25 × height) – (5 × age) + 5 // Women: (10 × weight) + (6.25 × height) – (5 × age) – 161 var bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age); if (isMale) { bmr += 5; } else { bmr -= 161; } // Calculate TDEE var tdee = bmr * activityMultiplier; // Display Results document.getElementById('displayBMR').innerHTML = Math.round(bmr).toLocaleString() + " kcal/day"; document.getElementById('displayTDEE').innerHTML = Math.round(tdee).toLocaleString() + " kcal/day"; // Populate Table var multipliers = [ { factor: 1.2, name: "Sedentary" }, { factor: 1.375, name: "Lightly Active" }, { factor: 1.55, name: "Moderately Active" }, { factor: 1.725, name: "Very Active" }, { factor: 1.9, name: "Extra Active" } ]; var tableHtml = ""; for (var i = 0; i < multipliers.length; i++) { var cal = Math.round(bmr * multipliers[i].factor); // Highlight selected activity var rowClass = (multipliers[i].factor === activityMultiplier) ? "tdee-row-highlight" : ""; tableHtml += ""; tableHtml += "" + multipliers[i].name + ""; tableHtml += "" + cal.toLocaleString() + " kcal"; tableHtml += ""; } document.getElementById('tdeeTableBody').innerHTML = tableHtml; // Show Results Div document.getElementById('bmrResult').style.display = 'block'; } // Initialize units display on load toggleBmrUnits();

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