Bmr Calculator

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bmr calculator
Metric (kg, cm)Imperial (lbs, ft/in)
MaleFemale
Basal Metabolic Rate (BMR)Sedentary (Little/no exercise)Lightly Active (1-3 days/week)Moderately Active (3-5 days/week)Very Active (6-7 days/week)Extra Active (Hard labor/2x training)
Results:
function toggleUnits(){var system=document.getElementById('unit_system').value;var weightLabel=document.getElementById('weightLabel');var metricRow=document.getElementById('metricHeightRow');var imperialRow=document.getElementById('imperialHeightRow');if(system==='metric'){weightLabel.innerHTML='Weight (kg):';metricRow.style.display='table-row';imperialRow.style.display='none';}else{weightLabel.innerHTML='Weight (lbs):';metricRow.style.display='none';imperialRow.style.display='table-row';}}function calculateBMR(){var system=document.getElementById('unit_system').value;var gender=document.getElementById('gender').value;var age=parseFloat(document.getElementById('age').value);var weight=parseFloat(document.getElementById('weight').value);var activity=parseFloat(document.getElementById('activity').value);var heightCm=0;if(isNaN(age)||isNaN(weight)){alert('Please enter valid numerical values.');return;}if(system==='metric'){heightCm=parseFloat(document.getElementById('heightCm').value);if(isNaN(heightCm)){alert('Please enter height.');return;}}else{var ft=parseFloat(document.getElementById('heightFt').value)||0;var inches=parseFloat(document.getElementById('heightIn').value)||0;heightCm=(ft*30.48)+(inches*2.54);weight=weight*0.453592;}var bmr=0;var s=(gender==='male')?5:-161;bmr=(10*weight)+(6.25*heightCm)-(5*age)+s;var tdee=bmr*activity;document.getElementById('mainBMR').innerHTML='BMR = '+Math.round(bmr).toLocaleString()+' Calories/day';document.getElementById('tdeeResult').innerHTML='Daily Energy Needs (TDEE): '+Math.round(tdee).toLocaleString()+' Calories/day';if(document.getElementById('steps').checked){var stepText='Calculation (Mifflin-St Jeor):
';stepText+='Weight: '+weight.toFixed(2)+' kg
';stepText+='Height: '+heightCm.toFixed(2)+' cm
';stepText+='Age: '+age+' years
';stepText+='Formula: (10 × '+weight.toFixed(1)+') + (6.25 × '+heightCm.toFixed(1)+') – (5 × '+age+') + ('+s+')
';stepText+='Result: '+bmr.toFixed(2)+' Calories';document.getElementById('stepDetails').innerHTML=stepText;document.getElementById('stepDetails').style.display='block';}else{document.getElementById('stepDetails').style.display='none';}document.getElementById('calculatorAnswer').style.display='block';}function resetCalculator(){document.getElementById('calculatorAnswer').style.display='none';}

BMR Calculator Use

The bmr calculator is an essential tool for anyone looking to manage their weight, build muscle, or optimize their nutrition. Basal Metabolic Rate (BMR) represents the number of calories your body requires to perform basic life-sustaining functions while at rest. These functions include breathing, blood circulation, cell production, and nutrient processing.

By entering your age, gender, weight, and height, this bmr calculator provides an estimate of your minimum daily caloric needs. Understanding this baseline is the first step in creating an effective diet or fitness plan.

Gender
Biological sex influences metabolic rate due to differences in muscle mass and hormonal profiles. Generally, men have higher BMRs than women.
Age
Metabolic rate typically decreases with age as lean muscle mass declines and fat mass increases.
Weight and Height
Larger bodies require more energy to maintain basic functions. Higher muscle-to-fat ratios significantly increase BMR.

How It Works: The Mifflin-St Jeor Equation

This bmr calculator utilizes 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. The formula is calculated based on metric units (kilograms and centimeters):

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

Once your BMR is calculated, we apply an Activity Multiplier to find your Total Daily Energy Expenditure (TDEE):

  • Sedentary (1.2): Little to no exercise, desk job.
  • Lightly Active (1.375): Light exercise or sports 1-3 days per week.
  • Moderately Active (1.55): Moderate exercise 3-5 days per week.
  • Very Active (1.725): Hard exercise 6-7 days per week.
  • Extra Active (1.9): Very hard exercise, physical job, or training twice a day.

BMR Calculation Example

Example: A 35-year-old male who weighs 180 lbs (81.65 kg) and is 6 feet tall (182.88 cm), working a moderately active job.

Step-by-step solution:

  1. Weight in kg: 180 / 2.2046 = 81.65 kg
  2. Height in cm: 72 inches × 2.54 = 182.88 cm
  3. BMR Formula: (10 × 81.65) + (6.25 × 182.88) – (5 × 35) + 5
  4. Sub-calculations: 816.5 + 1143.0 – 175 + 5
  5. BMR Result: 1,789.5 Calories/day
  6. TDEE (Moderate): 1,789.5 × 1.55 = 2,773.7 Calories/day

Common Questions

What is the difference between BMR and RMR?

BMR (Basal Metabolic Rate) is measured under very restrictive conditions (after 12 hours of fasting and 8 hours of sleep in a darkened room). RMR (Resting Metabolic Rate) is a more real-world measurement that doesn't require strict fasting or resting environments. For most users, the values are close enough to be used interchangeably in the bmr calculator.

How many calories should I eat to lose weight?

To lose weight, you generally need to consume fewer calories than your TDEE (Total Daily Energy Expenditure). A common approach is a deficit of 500 calories per day to lose roughly 1 pound per week. However, you should rarely consume fewer calories than your base BMR without medical supervision.

Does muscle mass increase my BMR?

Yes. Muscle tissue is more metabolically active than fat tissue. This means that two people of the same weight and height could have different results on a bmr calculator if one has a much higher percentage of muscle mass. While the Mifflin-St Jeor formula doesn't account for body fat percentage, it provides a highly reliable estimate for the average individual.

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