Resting Metabolic Rate Calculator to Lose Weight

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Resting Metabolic Rate (RMR) Calculator

Plan your weight loss journey with metabolic precision

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

Your Metabolic Profile

Your RMR
0
kcal/day
Maintenance
0
kcal/day
Weight Loss
0
kcal/day

*Weight loss target based on a 500-calorie daily deficit (approx. 0.5kg/1lb per week loss).

How to Use Your Resting Metabolic Rate to Lose Weight

Understanding your Resting Metabolic Rate (RMR) is the foundation of any successful weight loss strategy. Your RMR represents the total number of calories your body burns while at complete rest—the energy required to keep your heart beating, lungs breathing, and brain functioning.

The Science of RMR vs. BMR

While often used interchangeably, RMR is slightly different from Basal Metabolic Rate (BMR). BMR is measured under strict laboratory conditions after 12 hours of fasting, while RMR is measured under less restrictive conditions. For practical weight loss planning, this calculator uses the Mifflin-St Jeor Equation, which is currently considered the gold standard for predicting calorie needs in healthy adults.

Calculation Logic for Weight Loss

Our calculator follows a three-step process to help you reach your goals:

  1. Calculate RMR: We use your age, gender, weight, and height to determine your base energy needs.
  2. Determine TDEE: We multiply your RMR by your activity level (the "Pal" factor) to find your Total Daily Energy Expenditure. This is your "maintenance" number.
  3. Create a Deficit: To lose weight, you must consume fewer calories than your TDEE. This tool subtracts 500 calories from your TDEE to target a safe, sustainable weight loss of roughly 1 pound (0.5 kg) per week.

Example Weight Loss Scenario

Imagine a 35-year-old female weighing 80kg at 165cm tall who exercises 3 times a week (Moderately Active):

  • RMR: Approximately 1,515 calories.
  • Maintenance (TDEE): 1,515 x 1.55 = 2,348 calories.
  • Weight Loss Goal: 2,348 – 500 = 1,848 calories daily.

By sticking to 1,848 calories, she creates a 3,500-calorie deficit per week, which is the energy equivalent of one pound of body fat.

Expert Tips for Success

Never consume fewer calories than your calculated RMR without medical supervision. Consuming too few calories can lead to muscle loss and a slower metabolism, making long-term weight maintenance more difficult. Focus on high-protein intake and resistance training to preserve lean muscle mass while in a calorie deficit.

function calculateRMR() { 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); var resultsDiv = document.getElementById("rmr-results"); // Validation if (isNaN(age) || isNaN(weight) || isNaN(height) || age <= 0 || weight <= 0 || height <= 0) { alert("Please enter valid positive numbers for age, weight, and height."); return; } // Mifflin-St Jeor Equation var rmr = 0; if (gender === "male") { rmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { rmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } var tdee = rmr * activity; var weightLossCalories = tdee – 500; // Safety floor (don't suggest below RMR for safety in a simple calculator) if (weightLossCalories < rmr) { weightLossCalories = rmr; } // Display Results document.getElementById("rmr-val").innerHTML = Math.round(rmr).toLocaleString(); document.getElementById("tdee-val").innerHTML = Math.round(tdee).toLocaleString(); document.getElementById("loss-val").innerHTML = Math.round(weightLossCalories).toLocaleString(); resultsDiv.style.display = "block"; resultsDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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