BMR Calculator
If you’re trying to figure out how many calories your body needs before exercise, steps, or workouts are even considered, this calculator estimates your Basal Metabolic Rate (BMR)—the energy your body uses to keep you alive at rest. Use your BMR as the baseline for building a realistic maintenance, deficit, or surplus when you pair it with your activity level (TDEE).
Your Information
Your BMR Results
Your BMR
1998 cal/day
Calories burned at restWeekly BMR Burn
13983 cal/week
Total weekly burnFactors Affecting Your BMR
Your BMR is influenced by several factors:
Fixed Factors
- Age: 30 years (decreases ~2% per decade)
- Gender: Male
- Height: 5'10"
- Weight: 180 lbs
Variables You Can Change
- Build muscle (most effective)
- Get adequate sleep (7-9 hours)
- Manage stress levels
- Stay hydrated
Related Tools
Use these calculators to optimize your nutrition:
Understanding Basal Metabolic Rate
What is BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain essential functions. These functions include breathing, circulation, cell production, and maintaining body temperature. It's the minimum energy your body needs just to stay alive.
BMR Includes Energy for:
- Breathing and oxygen transport
- Maintaining heart rate and circulation
- Cell production and repair
- Maintaining body temperature
- Organ function (brain, kidneys, liver)
- Muscle maintenance
BMR vs TDEE
Many people confuse BMR with TDEE. Here's the key difference:
BMR (Basal Metabolic Rate): Calories burned at complete rest, doing nothing. Just the minimum your body needs.
TDEE (Total Daily Energy Expenditure): All calories burned daily including BMR + activities + exercise + digestion. This is what you actually burn.
Relationship: TDEE = BMR × Activity Level Multiplier (1.2 to 1.9)
Want the full breakdown of formulas, activity multipliers, and assumptions? See: Calculator Methodology (and the TDEE Calculator page for goal calories).
The Harris-Benedict Formula
This page uses Harris-Benedict to estimate BMR from age, height, weight, and gender. For the full equations, unit conversions, and related assumptions used across calculators, see: Calculator Methodology.
Example BMR Calculations
Example 1: Male, 30 years, 5'10", 180 lbs
Calculation:
- Height: 5'10" = 177.8 cm
- Weight: 180 lbs = 81.6 kg
- BMR = 88.362 + (4.8871 × 177.8) + (14.4454 × 81.6) - (4.6361 × 30)
- BMR = 88.362 + 869.08 + 1,178.95 - 139.08 = 1,997 calories/day
Example 2: Female, 28 years, 5'5", 140 lbs
Calculation:
- Height: 5'5" = 165.1 cm
- Weight: 140 lbs = 63.5 kg
- BMR = 447.593 + (3.098 × 165.1) + (9.247 × 63.5) - (4.3 × 28)
- BMR = 447.593 + 511.31 + 586.98 - 120.4 = 1,425 calories/day
Factors That Affect BMR
Factors You Can't Change:
- Age: BMR decreases ~2% per decade after age 30
- Gender: Males typically have 5-10% higher BMR than females
- Height: Taller people have higher BMR due to greater surface area
- Genetics: Natural variations in metabolism (±20%)
Factors You Can Change:
- Muscle Mass: Most effective - muscle tissue burns ~3x more calories than fat
- Sleep: Poor sleep (7-9 hours) can decrease BMR by 10-15%
- Stress: High stress increases cortisol, which can lower BMR
- Hydration: Dehydration can slow metabolism
- Calorie Intake: Very low calories trigger metabolic adaptation (lower BMR)
- Hormones: Thyroid function, sex hormones affect BMR
How to Use The BMR Calculator
Step 1: Pick the formula branch (male vs female)
Select Male or Female. This page uses gender-specific Harris-Benedict coefficients, so this choice determines which equation is used for your BMR.
Step 2: Enter the three inputs the BMR equation actually uses
Fill in age, height, and weight. These are the only variables this calculator needs to estimate the calories your body burns at complete rest.
Step 3: Use the BMR output as your “at-rest floor”
Read your BMR (cal/day) as the energy cost of simply staying alive without accounting for walking, training, or daily tasks. The weekly number is the same baseline multiplied by 7.
Step 4: Decide what to do next (BMR isn’t a calorie target)
This page does not set a deficit/surplus by itself. If you’re building a calorie plan, take this BMR to the TDEE Calculator to scale it by your activity level—then set your maintenance, cut, or surplus from that TDEE value.
Common Questions About BMR
Q: Why is BMR important for weight loss?
BMR is important because it determines your baseline calorie needs. Your TDEE (what you actually burn) is calculated by multiplying your BMR by your activity level. Knowing your BMR helps you determine how many calories to eat for weight loss, maintenance, or gain.
Q: Is the BMR calculation 100% accurate?
The Harris-Benedict formula is quite accurate (typically within 10-20% for most people), but individual variation exists based on muscle mass, genetics, hormones, and metabolic health. Use this as a starting estimate, then adjust based on real results after 2-3 weeks.
Q: Can I change my BMR?
Yes, you can increase your BMR by building muscle (most effective), getting adequate sleep, managing stress, staying hydrated, and eating enough calories. You cannot significantly change age or gender, but you can optimize the factors within your control.
Q: Should I eat my BMR or my TDEE?
You should base your calorie intake on your TDEE, not your BMR. Your TDEE includes all daily activities and exercise, while BMR is only rest metabolism. Eating at your BMR would create an extreme calorie deficit. Use TDEE as your baseline, then adjust from there.
Q: Why does BMR decrease with age?
BMR decreases with age due to: loss of muscle mass (natural decline), reduction in hormones like growth hormone and testosterone, decreased mitochondrial efficiency, and reduced cellular activity. This is why maintaining muscle through strength training becomes increasingly important as you age.
Pro Tips for Optimizing Your BMR
- Build Muscle: Strength training 3-4x/week increases BMR most effectively
- Prioritize Sleep: 7-9 hours nightly supports metabolism and recovery
- Eat Enough: Very low calories trigger metabolic adaptation (slows BMR)
- Include Protein: Protein has higher thermic effect than carbs or fats
- Stay Active: Regular movement increases TDEE beyond BMR
- Manage Stress: High cortisol can suppress BMR
- Recalculate: BMR changes with weight - recalculate every 4-6 weeks
Quick Reference
BMR by Gender:
Males: Typically 5-10% higher than females
Females: Typically lower due to less muscle mass
Age Effect:
BMR decreases ~2% per decade after age 30
BMR to TDEE:
- Sedentary: BMR × 1.2
- Lightly Active: BMR × 1.375
- Moderately Active: BMR × 1.55
- Very Active: BMR × 1.725
- Extremely Active: BMR × 1.9
What Affects BMR
Increases BMR:
- • Building muscle
- • Youth
- • Adequate calories
- • Good sleep
- • Stress management
Decreases BMR:
- • Age (after 30)
- • Low calories
- • Muscle loss
- • Poor sleep
- • High stress
Understanding TDEE
BMR: Calories at complete rest only
TDEE: BMR + all daily activities + exercise
Use TDEE for weight loss/gain calculations, not BMR