BMR Calculator
Calculate your Basal Metabolic Rate and daily calorie needs.
BMR Calculator
What Is the BMR Calculator?
The BMR Calculator (Basal Metabolic Rate Calculator) helps you determine the amount of energy your body expends while at complete rest. It provides your fundamental calorie needs and estimates how many calories you require daily based on various activity levels.
BMR is a crucial metric for anyone looking to lose, maintain, or gain weight, as it forms the baseline for your Total Daily Energy Expenditure (TDEE).
Practical Examples & Reference Guide
Example 1: Sedentary Lifestyle
- Profile: 30-year-old female, 165 cm, 65 kg
- BMR: ~1,410 kcal/day
- TDEE (Sedentary): ~1,692 kcal/day
Example 2: Active Lifestyle
- Profile: 25-year-old male, 180 cm, 80 kg
- BMR: ~1,840 kcal/day
- TDEE (Active): ~3,174 kcal/day
In-Depth Technical Guide
How Is BMR Calculated?
This tool supports three established formulas for estimating BMR:
1. Mifflin-St Jeor Equation
The most accurate standard formula for the general population.
2. Revised Harris-Benedict Equation
An older, widely used formula that provides slightly different estimates.
3. Katch-McArdle Formula
The most accurate if you know your exact Body Fat Percentage, as it calculates BMR based on Lean Body Mass.
What Affects Your BMR?
BMR varies significantly between individuals, even at the same height and weight. Four factors explain most of that difference:
Age
BMR gradually declines with age, generally by about 1–2% per decade after early adulthood, mainly because muscle mass tends to decrease and body fat tends to increase as people get older, and muscle burns more calories at rest than fat does.
Gender
Men typically have a higher BMR than women at the same height and weight, largely because men generally carry more muscle mass and less body fat on average — this is also why the Mifflin-St Jeor and Harris-Benedict formulas both include a separate constant for gender.
Muscle Mass
Muscle tissue is more metabolically active than fat tissue, meaning it burns more calories even while at complete rest. This is the exact reason the Katch-McArdle formula calculates BMR directly from Lean Body Mass Calculator results instead of from age and gender averages — it's built to capture this difference precisely rather than estimate around it.
Genetics
Some of the variation in BMR between two people of identical age, gender, height, and weight simply comes down to genetic differences in metabolic efficiency — which is part of why formula-based BMR estimates are a strong starting point, not an exact clinical measurement.
Average BMR by Age and Gender
| Age Group | Average BMR (Male) | Average BMR (Female) |
|---|---|---|
| 18–30 years | ~1,750 kcal/day | ~1,450 kcal/day |
| 31–50 years | ~1,650 kcal/day | ~1,400 kcal/day |
| 51–70 years | ~1,550 kcal/day | ~1,300 kcal/day |
| 71+ years | ~1,450 kcal/day | ~1,250 kcal/day |
These are population averages, not personal targets — your actual BMR depends on your specific height, weight, and body composition, which is exactly what the calculator above accounts for. A result noticeably above or below your age group's average is common and not inherently a cause for concern, particularly for anyone who is unusually tall, short, muscular, or lean relative to the general population these averages are drawn from. For more insights into your healthy weight target, you can check our Ideal Weight Calculator.
BMR Calculator vs Calorie Calculator: What's the Difference?
These two tools are closely related but built for different questions. This BMR Calculator isolates a single number: the calories your body burns at complete rest, with no activity, movement, or exercise factored in — useful on its own if you specifically want your baseline metabolic number, or if you're comparing how different formulas estimate that same baseline. The Calorie Calculator takes that same BMR calculation and adds an activity multiplier to produce your full Total Daily Energy Expenditure (TDEE), then translates that into practical daily calorie targets for weight loss, maintenance, or muscle gain. In short: use this page when you want your resting metabolic number on its own, and use the Calorie Calculator when you want a complete daily target based on your actual activity level and goal.
Frequently Asked Questions (FAQs)
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to estimate your total calorie needs for the day.
Which BMR formula should I use?
Mifflin-St Jeor is recommended for most people. If you know your body fat percentage, the Katch-McArdle formula will provide the most accurate results by factoring in your lean body mass.
What is a normal BMR?
For adults, BMR commonly falls between roughly 1,300 and 1,800 kcal/day, though this varies widely based on age, gender, height, weight, and muscle mass — there's no single "normal" number, which is why a personalized calculation is more useful than a general benchmark.
Can I increase my BMR?
Yes, to a degree — building muscle through strength training is the most reliable way to raise BMR over time, since muscle tissue burns more calories at rest than fat tissue. Getting adequate sleep and avoiding prolonged very-low-calorie dieting also help protect BMR from dropping, since severe or prolonged calorie restriction can cause the body to lower its resting energy use.