Bmr Calculator

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bmr calculator
Metric Units (kg, cm)US Units (lb, ft/in)
MaleFemale
Your Basal Metabolic Rate (BMR):
— Calories/day
function toggleUnits(){var type=document.getElementById('unit_type').value;var weightLabel=document.getElementById('weightLabel');var hMetric=document.getElementById('heightMetricRow');var hUS=document.getElementById('heightUSRow');if(type==='metric'){weightLabel.innerHTML='Weight (kg):';hMetric.style.display='table-row';hUS.style.display='none';}else{weightLabel.innerHTML='Weight (lbs):';hMetric.style.display='none';hUS.style.display='table-row';}}function calculateBMR(){var type=document.getElementById('unit_type').value;var gender=document.getElementById('gender').value;var age=parseFloat(document.getElementById('age').value);var weight=parseFloat(document.getElementById('weight').value);var bmr=0;var heightCM=0;var weightKG=0;if(type==='metric'){weightKG=weight;heightCM=parseFloat(document.getElementById('heightCM').value);}else{weightKG=weight*0.453592;var ft=parseFloat(document.getElementById('heightFT').value)||0;var inch=parseFloat(document.getElementById('heightIN').value)||0;heightCM=(ft*30.48)+(inch*2.54);}if(isNaN(age)||isNaN(weightKG)||isNaN(heightCM)){alert('Please fill in all fields correctly');return;}if(gender==='male'){bmr=(10*weightKG)+(6.25*heightCM)-(5*age)+5;}else{bmr=(10*weightKG)+(6.25*heightCM)-(5*age)-161;}document.getElementById('resultValue').innerHTML=Math.round(bmr).toLocaleString();var steps=document.getElementById('stepsOutput');if(document.getElementById('showSteps').checked){var s="Step-by-Step (Mifflin-St Jeor):
";s+="1. Gender constant: "+(gender==='male'?"+5″:"-161″)+"
";s+="2. Weight component (10 x "+weightKG.toFixed(2)+"kg): "+(10*weightKG).toFixed(2)+"
";s+="3. Height component (6.25 x "+heightCM.toFixed(2)+"cm): "+(6.25*heightCM).toFixed(2)+"
";s+="4. Age component (5 x "+age+"): "+(5*age)+"
";s+="5. Result: "+Math.round(bmr)+" Calories";steps.innerHTML=s;steps.style.display='block';}else{steps.style.display='none';}}

How to Use the BMR Calculator

A bmr calculator is an essential tool for anyone looking to manage their weight, improve their fitness, or understand their body's energy requirements. Basal Metabolic Rate (BMR) represents the number of calories your body burns while at rest to maintain vital functions such as breathing, circulation, and cell production.

To use this calculator, simply follow these steps:

  • Select your preferred unit system (Metric or US Units).
  • Choose your biological gender, as metabolic rates differ significantly between men and women.
  • Enter your current age in years.
  • Input your current weight and height accurately.
  • Click "Calculate" to see your daily baseline calorie needs.

What is Basal Metabolic Rate (BMR)?

Your BMR is the minimum level of energy required to keep your body functioning in a state of total rest. Even when you are sleeping or sitting perfectly still, your heart is pumping blood, your kidneys are filtering, and your brain is processing information. All these processes require energy in the form of calories.

Understanding your bmr calculator result is the first step toward creating a personalized nutrition plan. If you consume exactly your BMR and do absolutely no physical activity (which is rare), you would maintain your weight. In reality, most people need to multiply their BMR by an activity factor to find their Total Daily Energy Expenditure (TDEE).

The BMR Formula Explained

This calculator uses the Mifflin-St Jeor Equation, which is currently considered the most accurate standard for predicting BMR in healthy adults. Developed in 1990, it replaced the older Harris-Benedict formula.

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

Calculation Example

Let's calculate the BMR for a 35-year-old male who weighs 85 kg (187 lbs) and stands 180 cm (5'11") tall.

Step-by-step solution:

  1. Weight Factor: 10 × 85 = 850
  2. Height Factor: 6.25 × 180 = 1,125
  3. Age Factor: 5 × 35 = 175
  4. Apply Gender Constant: +5
  5. Total: 850 + 1,125 – 175 + 5 = 1,805 Calories/day

This means the individual burns approximately 1,805 calories just by existing without any added movement. To lose weight, they would typically aim for a caloric intake slightly below their TDEE (BMR + activity), but rarely below their BMR without medical supervision.

Common Questions

How accurate is a bmr calculator?

While the Mifflin-St Jeor equation is highly regarded, no calculator is 100% accurate. Factors like muscle mass (which burns more calories than fat), genetics, and hormonal health can influence your actual metabolic rate. People with high muscle mass may find the calculator underestimates their needs.

Does BMR decrease with age?

Yes, BMR generally decreases as you get older. This is often due to a natural loss of lean muscle tissue and changes in hormonal balance. Staying active and performing resistance training can help mitigate this decline by maintaining muscle mass.

What is the difference between BMR and RMR?

Basal Metabolic Rate (BMR) is measured under very strict, restrictive conditions (usually after 12 hours of fasting and 8 hours of sleep). Resting Metabolic Rate (RMR) is a similar metric but measured under less restrictive conditions. For most practical purposes, they are used interchangeably in a bmr calculator.

Should I eat less than my BMR to lose weight?

Eating below your BMR is generally not recommended without a doctor's guidance. Since your BMR represents the energy needed for vital organ function, consistent under-eating can lead to muscle loss, nutrient deficiencies, and a "slowed" metabolism as the body attempts to conserve energy.

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