BMR Calculator: Calculate Your Basal Metabolic Rate
Use this free BMR calculator to find out how many calories your body burns at rest every day. Your Basal Metabolic Rate (BMR) is the energy your body needs just to keep you alive: breathing, circulating blood, and running your organs. Enter your age, sex, height and weight to get your BMR from four trusted formulas, plus your daily calorie needs at every activity level. Works in imperial (lbs, ft) and metric (kg, cm).
Your daily calories by activity level
BMR by formula
Estimates only. Real BMR varies by about 5-10% between people with the same stats.
What Is BMR (Basal Metabolic Rate)?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest in 24 hours to maintain basic life functions: breathing, blood circulation, body temperature, cell repair and brain activity. It accounts for roughly 60-70% of the calories you burn each day, making it the biggest piece of your energy budget.
BMR is measured under strict conditions: lying down, fully rested, after fasting for 12 hours, in a comfortable temperature. A close cousin, RMR (Resting Metabolic Rate), is measured under looser conditions and is usually slightly higher. For everyday use, the terms are often used interchangeably.
BMR vs RMR vs TDEE
| Term | What it means |
|---|---|
| BMR | Calories burned at complete rest to keep you alive |
| RMR | Calories burned at rest in normal conditions, slightly higher than BMR |
| TDEE | Total calories burned per day, including BMR, digestion, daily movement and exercise |
BMR is the starting point. Multiply it by an activity factor and you get your TDEE, the number you actually use to plan weight loss, maintenance or muscle gain.
How This BMR Calculator Works
The calculator offers four widely used equations. In the formulas below, weight is in kilograms, height is in centimeters and age is in years.
Men: BMR = 10 x weight + 6.25 x height - 5 x age + 5
Women: BMR = 10 x weight + 6.25 x height - 5 x age - 161
Revised Harris-Benedict (1984)
Men: BMR = 88.362 + 13.397 x weight + 4.799 x height - 5.677 x age
Women: BMR = 447.593 + 9.247 x weight + 3.098 x height - 4.330 x age
Katch-McArdle
BMR = 370 + 21.6 x lean body mass (kg)
Cunningham
BMR = 500 + 22 x lean body mass (kg)
Which Formula Should You Use?
- Mifflin-St Jeor: the best default for most people. Studies have found it to be the most accurate of the formulas that use only height, weight, age and sex.
- Revised Harris-Benedict: a classic that tends to run slightly higher than Mifflin-St Jeor.
- Katch-McArdle: uses lean body mass, so it is better for people who are very lean or very muscular. It needs a reasonably accurate body fat percentage.
- Cunningham: similar to Katch-McArdle but built for athletes and often gives a higher result.
From BMR to Daily Calories
To estimate how many calories you burn in a full day, multiply your BMR by an activity factor:
| Activity level | Multiplier | Description |
|---|---|---|
| Sedentary | x 1.2 | Little or no exercise |
| Lightly active | x 1.375 | Exercise 1-3 days per week |
| Moderately active | x 1.55 | Exercise 3-5 days per week |
| Very active | x 1.725 | Hard exercise 6-7 days per week |
| Extra active | x 1.9 | Very hard exercise and a physical job |
The result is your TDEE (Total Daily Energy Expenditure). Eat around it to maintain your weight, below it to lose weight, and above it to gain.
What Affects Your BMR?
- Body size: larger bodies burn more calories, even at rest.
- Muscle mass: muscle is more metabolically active than fat, so more muscle means a higher BMR.
- Age: BMR tends to decline with age, mostly because muscle mass drops.
- Sex: men usually have a higher BMR than women of the same weight because they typically carry more lean mass.
- Genetics: some people naturally burn more or fewer calories than formulas predict.
- Hormones: thyroid hormones strongly influence metabolic rate, and conditions such as hypothyroidism can lower it.
- Pregnancy, breastfeeding, illness and fever: all raise energy needs.
- Dieting: long periods of low calorie intake can reduce BMR a little as the body adapts.
Typical BMR Ranges
As a rough guide, many adult women have a BMR of about 1,300-1,500 calories per day, and many adult men about 1,600-1,900 calories per day. Your own number can fall outside these ranges depending on size, muscle and age, so use the calculator for a personalized estimate.
How to Increase Your BMR
- Build muscle. Strength training 2-4 times per week helps preserve and grow muscle, which supports a higher BMR as you age.
- Eat enough protein. Protein has the highest thermic effect, meaning your body burns more calories digesting it. Aim for about 1.6-2.2 g per kg if you train.
- Avoid extreme dieting. Large, long calorie deficits can reduce muscle and slow your metabolism. Use a moderate deficit instead.
- Move more through the day. Daily steps and general activity (NEAT) can add hundreds of calories to your TDEE.
- Sleep 7-9 hours. Poor sleep disrupts hunger hormones and can affect metabolism and recovery.
Be careful with "metabolism boosting" supplements and foods. Things like green tea, coffee and spicy food raise energy expenditure only slightly, and no supplement replaces good training and nutrition.
Should You Eat Your BMR to Lose Weight?
No. BMR is not a calorie target for weight loss. It only covers your body's resting needs, not daily movement or exercise. Eating at or below your BMR for a long time can cause fatigue, muscle loss and nutrient shortfalls. Base your plan on your TDEE and create a moderate deficit of about 10-25% below it.
Frequently Asked Questions About BMR
What is a good BMR?
There is no good or bad BMR. It depends on your size, age, sex and muscle mass. A higher BMR simply means your body burns more calories at rest.
How do I calculate my BMR?
Enter your age, sex, height and weight into the calculator above. It uses the Mifflin-St Jeor formula by default, and you can compare with the Harris-Benedict, Katch-McArdle and Cunningham formulas.
Is BMR the same as the calories I should eat?
No. BMR is only the energy your body burns at rest. Your daily needs are higher once you include movement and exercise, which is your TDEE.
How accurate is a BMR calculator?
Formulas are usually within about 5-10% of measured BMR for most people. For a more exact number, a lab test using indirect calorimetry can measure it directly, but a calculator is accurate enough for most plans.
Does BMR decrease with age?
It generally declines gradually with age, mainly because people lose muscle mass. Strength training and enough protein can help slow this decline.
Does drinking water boost BMR?
Drinking cold water may burn a few extra calories, but the effect is very small. Water is still important for health and for managing hunger.
Why is my BMR different on different calculators?
Each formula was built from different groups of people and uses different variables. Results can differ by 100-200 calories. Pick one formula and track your real weight changes to fine-tune.
Disclaimer: This calculator is for educational purposes only and is not medical advice. Consult a doctor or registered dietitian before starting a new diet, especially if you are pregnant, under 18, have a thyroid condition or other medical condition, or have a history of disordered eating.
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