Metabolic Rate Calculator
Use this calculator to estimate your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE).
Formula used: Mifflin-St Jeor Equation. Estimates are for educational use.
What this online metabolic rate calculator tells you
Your body burns calories all day long—even when you are sleeping, breathing, or just sitting still. That baseline calorie use is your metabolic rate. This calculator helps you estimate:
- BMR (Basal Metabolic Rate): calories burned at complete rest
- TDEE (Total Daily Energy Expenditure): BMR adjusted for movement and exercise
- Target intake: daily calories based on your chosen goal (maintain, lose, or gain)
If you have ever wondered “How many calories should I eat?”, this is the practical place to start.
BMR vs RMR vs TDEE
BMR (Basal Metabolic Rate)
BMR is the number of calories your body needs to keep you alive in a fully rested state. It reflects essential biological functions like heart activity, circulation, temperature regulation, hormone function, and cellular repair.
RMR (Resting Metabolic Rate)
RMR is similar to BMR, but measured in less strict conditions. In many online tools and fitness apps, BMR and RMR are used interchangeably. For planning purposes, they are close enough for most people.
TDEE (Total Daily Energy Expenditure)
TDEE includes everything: your baseline metabolism, non-exercise movement (walking, chores, fidgeting), planned workouts, and digestion. This is usually the most useful number when planning nutrition.
How this calculator works
The calculator uses the widely accepted Mifflin-St Jeor equation to estimate BMR from age, sex, height, and weight. Then it multiplies your BMR by an activity factor to estimate TDEE.
- Male BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Female BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
- TDEE = BMR × activity multiplier
Finally, your chosen calorie goal is added or subtracted to produce a daily target intake.
How to use your number effectively
1) Start with your estimated target
Use the result as your starting daily calorie intake for 2–3 weeks.
2) Track body weight trends
Weigh yourself consistently (same time of day, same conditions), and look at weekly averages instead of day-to-day fluctuations.
3) Adjust slowly
- If weight is not moving as expected, adjust by 100–200 calories/day.
- Avoid aggressive cuts or bulks unless medically supervised.
- Keep protein intake high and resistance train when possible.
Key factors that influence metabolic rate
- Body size and composition: larger bodies and more lean mass typically burn more calories.
- Age: metabolism often declines gradually with age.
- Sex: average differences in lean mass affect calorie needs.
- Activity level: daily movement can significantly raise total expenditure.
- Sleep and stress: poor recovery can affect hunger, energy, and adherence.
- Medical conditions: thyroid issues and other conditions may alter energy use.
Practical calorie targets by goal
Fat loss
A moderate deficit (about 300–500 calories/day) is often easier to sustain than extreme dieting. Aim for steady progress and protect lean mass with adequate protein and strength training.
Maintenance
Maintenance calories are useful for stabilizing weight, improving training performance, and building healthy habits without aggressive scale changes.
Muscle gain
A small surplus (around 200–300 calories/day) often supports leaner gains than very large surpluses, especially for intermediate and advanced trainees.
Frequently asked questions
Is this calculator 100% accurate?
No calculator can perfectly predict real-world metabolism. Think of this as a well-researched estimate, then personalize based on your progress data.
How often should I recalculate?
Recalculate when your body weight changes meaningfully (e.g., 5–10 lb / 2–5 kg), when activity level changes, or every 6–8 weeks during a focused phase.
Can I use this if I am very athletic?
Yes, but highly active athletes may need more individualized adjustments, especially during heavy training blocks.
Bottom line
An online metabolic rate calculator is a strong first step for nutrition planning. Use your estimated BMR and TDEE to set a realistic target, monitor outcomes, and refine your intake over time. Consistency beats perfection—small, sustainable adjustments usually produce the best long-term results.