Resting Metabolic Rate Calculator

RMR Calculator

Calculate your Resting Metabolic Rate and daily calorie needs

Age (years)

Gender Male Female

Height (cm)

Weight (kg)

Calculation Formula

Mifflin-St Jeor

Harris-Benedict

Katch-McArdle

Body Fat Percentage (required for Katch-McArdle)

Activity Level Sedentary (little or no exercise) Lightly active (light exercise 1-3 days/week) Moderately active (moderate exercise 3-5 days/week) Very active (hard exercise 6-7 days/week) Extra active (very hard exercise & physical job)

Your Metabolic Results

1,650 kcal

Resting Metabolic Rate (RMR) 1,650 kcal/day

Daily Calorie Needs (TDEE) 2,558 kcal/day

Formula Used Mifflin-St Jeor

Daily Calorie Needs Based on Activity Level

Sedentary

Light

Moderate

Active

Extra

1,980 kcal 2,270 kcal 2,558 kcal 2,848 kcal 3,135 kcal

Interpretation

Your Resting Metabolic Rate (RMR) represents the calories your body burns at complete rest. To maintain your current weight, consume your Total Daily Energy Expenditure (TDEE) calories. For weight loss, consume 300-500 kcal less than your TDEE, and for weight gain, consume 300-500 kcal more.

Weight Maintenance Calories 2,558 kcal/day

Mild Weight Loss (0.25 kg/week) 2,308 kcal/day

Weight Loss (0.5 kg/week) 2,058 kcal/day

Extreme Weight Loss (1 kg/week) 1,558 kcal/day

×

About Resting Metabolic Rate

Resting Metabolic Rate (RMR) is the number of calories your body burns at complete rest to maintain basic physiological functions like breathing, circulation, and cell production.

Key Concepts

• RMR: Calories burned at complete rest (60-75% of daily expenditure)
• TDEE: Total Daily Energy Expenditure (RMR + activity + digestion)
• BMR vs RMR: BMR is measured in stricter conditions than RMR

Calculation Formulas

• Mifflin-St Jeor (most accurate for most people):
  Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
  Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
• Harris-Benedict (older formula):
  Men: 88.362 + (13.397 × weight) + (4.799 × height) - (5.677 × age)
  Women: 447.593 + (9.247 × weight) + (3.098 × height) - (4.330 × age)
• Katch-McArdle (requires body fat %):
  370 + (21.6 × lean body mass in kg)
  Lean Mass = Weight × (100 - Body Fat %) / 100

Activity Multipliers

Level	Multiplier	Description
Sedentary	1.2	Little or no exercise
Lightly active	1.375	Light exercise 1-3 days/week
Moderately active	1.55	Moderate exercise 3-5 days/week
Very active	1.725	Hard exercise 6-7 days/week
Extra active	1.9	Very hard exercise & physical job

Factors Affecting RMR

• Age: RMR decreases about 2-3% per decade after 20
• Body Composition: Muscle burns more calories than fat
• Gender: Men typically have higher RMR due to more muscle mass
• Genetics: Some people naturally have faster/slower metabolism
• Hormones: Thyroid hormones significantly affect metabolic rate

What is Resting Metabolic Rate (RMR)?

Resting Metabolic Rate (RMR) is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production. It accounts for 60-75% of your total daily energy expenditure (TDEE) and is influenced by age, gender, weight, height, and body composition.

RMR vs. BMR (Basal Metabolic Rate)

• BMR is measured under strict lab conditions (after 12 hours of fasting and sleep).

• RMR is a more practical estimate (measured under less strict conditions).

• For most people, the terms are used interchangeably.

---

How is RMR Calculated?

Several equations estimate RMR. The most accurate ones are:

1. Mifflin-St Jeor Equation (Most Accurate for General Population)

• Men:
  RMR (kcal/day) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

• Women:
  RMR (kcal/day) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Example (30-year-old woman, 165 cm, 65 kg):

= (10 × 65) + (6.25 × 165) – (5 × 30) – 161
= 650 + 1,031.25 – 150 – 161 ≈ **1,370 kcal/day**

2. Harris-Benedict Equation (Older but Still Used)

• Men:
  RMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age)

• Women:
  RMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age)

3. Katch-McArdle Formula (Best for Lean Body Mass)

• Requires body fat percentage (more accurate for athletes).

• Formula (Men & Women):
  RMR = 370 + (21.6 × Lean Body Mass in kg)

Example (70 kg person with 20% body fat):

Lean Mass = 70 kg × 0.80 = 56 kg
RMR = 370 + (21.6 × 56) ≈ **1,580 kcal/day**

---

Factors Affecting RMR

Factor	Effect on RMR
Muscle Mass	↑ More muscle = higher RMR
Age	↓ Decreases with age (loss of muscle)
Gender	♂ Men typically have higher RMR (more muscle)
Hormones	Thyroid issues can ↑ or ↓ RMR
Body Size	↑ Taller/heavier people burn more at rest
Genetics	Some people naturally have faster/slower metabolism

---

How to Use an RMR Calculator

1. Input:

   • Weight (kg/lbs)

   • Height (cm/ft)

   • Age

   • Gender

   • (Optional) Body fat %

2. Output:

   • Estimated daily calories burned at rest

   • Adjustments for activity level (to get TDEE)

3. Application:

   • Weight Loss: Eat below RMR + activity calories.

   • Muscle Gain: Eat above RMR + activity calories.

---

Limitations of RMR Calculators

• Do not account for:

  • Non-exercise activity thermogenesis (NEAT)

  • Digestive thermic effect (TEF)

  • Metabolic adaptation (changes with dieting)

• Lab tests (indirect calorimetry) are more accurate.

---

How to Increase RMR Naturally

✅ Build muscle (strength training)
✅ Stay active (NEAT: walking, standing)
✅ Eat enough protein (higher thermic effect)
✅ Avoid extreme diets (very low calories ↓ RMR)

---

Example RMR Calculation for Weight Loss

• RMR = 1,500 kcal

• Lightly Active (TDEE = RMR × 1.375) ≈ 2,062 kcal/day

• For weight loss (500 kcal deficit): Eat ~1,560 kcal/day