RMR Calculator
Use this free resting metabolic rate calculator to estimate how many calories your body burns each day at rest. You can also estimate your daily maintenance calories based on your activity level.
What is RMR?
RMR stands for resting metabolic rate. It is the number of calories your body needs each day to support essential functions while you are at rest. These functions include breathing, blood circulation, cell repair, hormone regulation, and temperature control.
In simple terms, your RMR is the baseline energy cost of staying alive. Even if you lie in bed all day, your body still burns calories. Knowing your RMR can help you set better calorie targets for weight loss, weight maintenance, or muscle gain.
How this RMR calculator works
This calculator converts your input into metric units and then applies one of two common formulas. The result is an estimate of your resting calorie burn.
1) Mifflin-St Jeor Equation
This is the default option because it is widely used in nutrition and coaching settings.
- Male:
RMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5 - Female:
RMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161
2) Revised Harris-Benedict Equation
This is an older but still useful model.
- Male:
RMR = 88.362 + 13.397 × weight(kg) + 4.799 × height(cm) - 5.677 × age - Female:
RMR = 447.593 + 9.247 × weight(kg) + 3.098 × height(cm) - 4.330 × age
RMR vs BMR vs TDEE
RMR (Resting Metabolic Rate)
Calories burned at rest under normal living conditions.
BMR (Basal Metabolic Rate)
Similar concept, but measured under stricter lab conditions (fasted, complete rest, controlled environment).
TDEE (Total Daily Energy Expenditure)
Your full daily burn, including movement, exercise, and digestion. In this calculator, TDEE is estimated by multiplying your RMR by an activity factor.
How to use your result
- Weight maintenance: Start near your estimated TDEE.
- Fat loss: Try a 300-500 calorie daily deficit from TDEE.
- Muscle gain: Try a 150-300 calorie daily surplus from TDEE.
Track body weight trends, waist measurements, gym performance, and energy levels. If progress stalls for 2-3 weeks, make small adjustments of 100-200 calories.
What affects RMR?
Your metabolic rate is not fixed forever. It changes with your body and lifestyle. Major factors include:
- Body size and lean mass
- Age
- Sex
- Genetics
- Hormonal status
- Sleep quality and stress load
- Diet history and prolonged calorie restriction
Tips for better calorie planning
Use estimates as a starting point
No calculator can perfectly predict individual metabolism. Use your calculated value to set a starting target, then refine based on weekly results.
Prioritize protein and resistance training
High-protein diets and strength training help preserve or build lean mass, which supports a healthier metabolic rate over time.
Avoid extreme deficits
Aggressive calorie cuts may reduce performance and recovery. Moderate, sustainable deficits usually produce better long-term outcomes.
Frequently asked questions
Is this RMR calculator accurate?
It is reasonably accurate for many adults, but it is still an estimate. Individual differences can be significant.
Should I recalculate after losing weight?
Yes. Recalculate every 5-10 pounds (2-5 kg) of change, or every 4-8 weeks during active dieting or bulking phases.
What if my progress does not match the calculator?
Adjust your target up or down by 100-200 calories and monitor for 10-14 days. Your real-world response is the most useful feedback.
Bottom line
An RMR calculator is a practical tool for setting smarter calorie targets. It gives you a science-based starting point, and your real progress helps fine-tune the plan. Use the estimate, track trends, and make consistent adjustments for better long-term results.