Determine your Resting Metabolic Rate (RMR) using the Mifflin-St Jeor and Harris-Benedict equations. Calculate daily calorie needs at complete rest.
A 30-year-old male weighing 80 kg (176 lbs) and 180 cm (5'11") tall.
Mifflin-St Jeor: 10(80) + 6.25(180) - 5(30) + 5 = 1,775 kcal/day
Harris-Benedict: 66.5 + 13.75(80) + 5(180) - 6.78(30) = 1,808 kcal/day
TDEE (Moderate Activity): ~1,775 × 1.55 = 2,751 kcal/day
This individual needs about 1,775 calories at complete rest and ~2,750 calories daily with moderate exercise.
A 45-year-old female weighing 65 kg (143 lbs) and 165 cm (5'5") tall.
Mifflin-St Jeor: 10(65) + 6.25(165) - 5(45) - 161 = 1,306 kcal/day
Harris-Benedict: 655 + 9.56(65) + 1.85(165) - 4.68(45) = 1,399 kcal/day
TDEE (Sedentary): ~1,306 × 1.20 = 1,567 kcal/day
This individual needs about 1,306 calories at complete rest and ~1,567 calories daily with a sedentary lifestyle.
A 25-year-old male weighing 75 kg (165 lbs) and 178 cm (5'10") tall who exercises intensely daily.
Mifflin-St Jeor: 10(75) + 6.25(178) - 5(25) + 5 = 1,723 kcal/day
Harris-Benedict: 66.5 + 13.75(75) + 5(178) - 6.78(25) = 1,775 kcal/day
TDEE (Very Active): ~1,723 × 1.9 = 3,274 kcal/day
With intense daily training, this individual needs approximately 3,274 calories daily to maintain weight.
A 65-year-old female weighing 58 kg (128 lbs) and 160 cm (5'3") tall.
Mifflin-St Jeor: 10(58) + 6.25(160) - 5(65) - 161 = 1,074 kcal/day
Harris-Benedict: 655 + 9.56(58) + 1.85(160) - 4.68(65) = 1,243 kcal/day
TDEE (Light Activity): ~1,074 × 1.375 = 1,477 kcal/day
Metabolic rate naturally declines with age. This individual needs around 1,074 calories at rest and ~1,477 calories daily.
Resting Metabolic Rate (RMR) is the number of calories your body burns while at complete rest. It accounts for the energy required to maintain vital body functions such as breathing, circulation, cell production, and temperature regulation. RMR typically makes up 60-75% of your total daily energy expenditure.
RMR (Resting Metabolic Rate) is measured under less strict conditions than BMR. It is typically measured after 3-4 hours of rest and a light meal, while BMR (Basal Metabolic Rate) requires 8-12 hours of fasting and complete rest immediately after waking. In practice, RMR is usually 10-20% higher than BMR due to the less controlled measurement conditions, but the terms are often used interchangeably in clinical and fitness settings.
Use your current weight (morning weight is most accurate) and your true height without shoes. Even small measurement errors can affect the result.
The Mifflin-St Jeor is generally more accurate for the general population, but comparing both gives you a range to work with for your nutrition planning.
As your weight changes with diet or exercise, your RMR changes too. Recalculate every 4-6 weeks during a fitness program for the most accurate guidance.
RMR equations provide estimates. For precise metabolic testing, consider indirect calorimetry performed by a healthcare professional or sports nutritionist.
Your Total Daily Energy Expenditure (TDEE) is calculated by multiplying your RMR by an activity factor that corresponds to your typical weekly exercise level. Choose the description that best matches your lifestyle.
Description: Little to no exercise. Desk job with minimal movement throughout the day.
Examples: Office workers who sit most of the day, remote workers, individuals with limited physical activity.
Typical TDEE Range: RMR × 1.20
Description: Light exercise or sports 1-3 days per week.
Examples: Walking 20-30 minutes daily, light yoga, casual cycling, weekend recreational sports.
Typical TDEE Range: RMR × 1.375
Description: Moderate exercise or sports 3-5 days per week.
Examples: Jogging 30-45 minutes most days, gym workouts 3-4 times weekly, swimming, moderate hiking.
Typical TDEE Range: RMR × 1.55
Description: Hard exercise or sports 6-7 days per week.
Examples: Daily intense gym sessions, athletic training, physically demanding jobs with regular exercise.
Typical TDEE Range: RMR × 1.725
Description: Very hard daily exercise or intense physical job, often with training twice a day.
Examples: Professional athletes, marathon runners, military training, construction workers who also train, competitive bodybuilders.
Typical TDEE Range: RMR × 1.9
When selecting your activity level, be honest with yourself about your actual exercise habits. Many people tend to overestimate their activity level. If you're unsure, choose the lower option — you can always adjust based on results. For weight loss, using a slightly lower activity factor gives a more conservative calorie target, which is generally safer and more effective.
Remember that NEAT (Non-Exercise Activity Thermogenesis) — activities like walking to work, cleaning, taking stairs, and fidgeting — also contributes to your total daily burn. If you have an active job or lifestyle outside of formal exercise, you may be at a higher activity level than the exercise-only descriptions suggest.
Resting Metabolic Rate (RMR) — also known as Resting Energy Expenditure (REE) — is the amount of energy (calories) your body needs to perform basic life-sustaining functions while at rest. These functions include breathing, circulating blood, regulating body temperature, cell growth and repair, and brain and nervous system activity. Your RMR accounts for approximately 60-75% of your total daily calorie burn, making it the single largest component of your energy expenditure.
RMR is often used interchangeably with Basal Metabolic Rate (BMR), though there are subtle differences. BMR is measured under more controlled conditions — immediately after waking, after 8-12 hours of fasting, and in a thermoneutral environment. RMR is measured under slightly less restrictive conditions and is typically about 10-20% higher than BMR. In practical clinical and fitness settings, the terms are used interchangeably, and our RMR Calculator provides reliable estimates for both.
Understanding your RMR is the foundation of any effective weight management plan. Knowing how many calories your body burns at rest helps you establish an accurate baseline for your daily calorie needs. If you consume more calories than your total daily energy expenditure (TDEE), you will gain weight. If you consume fewer, you will lose weight. The calorie deficit or surplus required for weight change is typically 500-1,000 calories per day for a safe rate of 0.5-1 kg (1-2 lbs) per week.
Crash diets with extremely low calorie intake can actually lower your RMR as your body enters a conservation mode. This is why sustainable, moderate calorie deficits combined with strength training to maintain muscle mass are recommended for long-term weight management success.
Our RMR Calculator uses two of the most widely validated predictive equations for estimating resting metabolic rate. Both were developed using regression analysis of direct and indirect calorimetry measurements.
Published in 1990 by Mifflin et al., this equation is considered the most accurate predictive equation for estimating RMR in the general population. It was developed using a sample of 498 healthy individuals and has been validated in numerous subsequent studies. The equation tends to be more accurate than Harris-Benedict, especially in overweight and obese populations. The American Dietetic Association recommends the Mifflin-St Jeor equation as the most reliable for clinical use.
The original Harris-Benedict equation was developed in 1919 based on 239 healthy individuals. While it was the gold standard for much of the 20th century, it was found to overestimate RMR in modern populations (who tend to be heavier and less active). The equation was revised in 1984 by Roza and Shizgal to better reflect contemporary body compositions. Despite being less accurate than Mifflin-St Jeor for many individuals, it remains widely used and provides a useful comparison point.
For most people, the Mifflin-St Jeor equation is recommended as your primary RMR estimate. However, we provide both equations so you can compare and use the average of both values as a more comprehensive estimate. If the two results differ significantly (more than 100-150 calories), consider consulting a healthcare professional for more precise metabolic testing via indirect calorimetry.
⚠️ Important Medical Disclaimer: This RMR Calculator provides estimates based on population-derived equations (Mifflin-St Jeor and Harris-Benedict) and should be used for informational and educational purposes only. These calculations are not a substitute for professional medical advice, diagnosis, or treatment. Individual metabolic rates vary based on genetics, body composition, medical conditions, medications, and other factors. Always consult a qualified healthcare provider, registered dietitian, or certified nutritionist before starting any diet, weight loss, or fitness program, especially if you have underlying health conditions.