BMR & TDEE Calculator
Health & Fitness
Estimate BMR and TDEE with Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle, then set a calorie goal in a private, browser-based calculator.
How to use this tool
- Enter your details. Select your sex, then enter your age, weight, and height. Toggle between metric and imperial units.
- Choose activity level. Select the activity level that best describes your typical week, from sedentary to extra active.
- Set your goal. Choose a goal - maintain weight, lose weight, or gain weight - to see an adjusted calorie target.
- Compare formulas. Choose Mifflin-St Jeor, revised Harris-Benedict, or Katch-McArdle, then calculate again to compare estimates. Katch-McArdle also requires a body-fat estimate.
What is BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest: the energy needed to keep your heart beating, lungs breathing, and organs functioning. BMR typically accounts for 60–70% of total daily energy expenditure.
What is TDEE?
Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that reflects how much you move throughout the day. A sedentary person (1.2×) burns far fewer calories than someone with a physically demanding job (1.9×).
Mifflin-St Jeor vs Harris-Benedict
The Mifflin-St Jeor equation (1990) is the more modern formula and is recommended by most dietitians as the most accurate for general use. The Harris-Benedict equation (revised 1984) tends to overestimate BMR by about 5% on average. Both are estimates; individual metabolism varies by genetics, muscle mass, hormones, and more.
Activity level multipliers
| Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise | 1.2× |
| Lightly active | Exercise 1–3 days/week | 1.375× |
| Moderately active | Exercise 3–5 days/week | 1.55× |
| Very active | Hard exercise 6–7 days/week | 1.725× |
| Extra active | Physical job or 2× training/day | 1.9× |
Caloric targets for goals
Once you know your TDEE, you can set a caloric target based on your goal:
- Maintain weight: eat at TDEE.
- Lose weight: the −500 kcal/day option is a rough estimate for a larger deficit; actual weight change varies and is not guaranteed by this calculation.
- Lose weight (~0.5 lb/week): eat at TDEE − 250 kcal/day. More sustainable for most people; better preserves muscle mass.
- Modest gain: the +250 kcal/day option is a moderate surplus to start with. The +500 kcal/day option is more aggressive and may not suit everyone. Neither option guarantees a particular weekly rate of weight or muscle gain.
These are starting estimates. Adjust based on real-world results after 2–3 weeks, since individual metabolic variation means actual weight change often differs from predictions.
For weight-loss goals, the result display uses a general floor of 1,200 kcal/day for women or 1,500 kcal/day for men, based on common low-calorie ranges. These values are not universal minimums or personalized requirements, and a floor above estimated TDEE will not create a calorie deficit. Low-calorie plans should be discussed with a healthcare professional. See MedlinePlus guidance on rapid weight-loss diets for more context.
Katch-McArdle formula
A third BMR formula - the Katch-McArdle equation - calculates BMR from lean body mass (LBM) rather than total body weight. Select it in the calculator and enter a body-fat estimate to use this equation:
BMR = 370 + (21.6 × LBM in kg)
where LBM = total weight × (1 − body fat fraction). This estimate depends on body-fat accuracy, so an incorrect percentage can shift the result. It may be useful when a reasonably reliable body-fat estimate is available, but it is not a clinical measurement. See the Body Fat Calculator or Lean Body Mass Calculator for related estimates.
Frequently asked questions
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest - just to keep your organs functioning. It accounts for about 60–70% of total calorie expenditure. BMR increases with more muscle mass and decreases with age.
What is TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day, including physical activity. It is calculated by multiplying your BMR by an activity multiplier ranging from 1.2 (sedentary) to 1.9 (extremely active).
Which formula is more accurate - Mifflin-St Jeor or Harris-Benedict?
Mifflin-St Jeor is commonly used for general estimates, while revised Harris-Benedict is another option. Katch-McArdle uses estimated lean body mass and may be useful when body-fat data is reasonably accurate. No equation predicts an individual’s needs exactly, and errors in a body-fat estimate also affect Katch-McArdle results.
How many calories should I eat to lose weight?
A 250- or 500-calorie daily deficit is a rough starting estimate, not a promised rate of weight change. For weight-loss goals, this calculator applies a display floor of 1,200 kcal/day for women or 1,500 kcal/day for men, based on common low-calorie ranges. These are not universal minimums or personalized requirements; low-calorie plans should be discussed with a healthcare professional. A floor above estimated TDEE will not create a calorie deficit.
Why does activity level affect calorie needs so much?
A sedentary person burns calories mainly through BMR. A very active person might burn 50–60% more calories per day through exercise and daily movement (NEAT - non-exercise activity thermogenesis). This is why two people with the same BMR can have very different TDEE values.
Related tools
- MacrosTurn the calorie target calculated here into daily protein, carb, and fat grams.
- Calorie TrackerUse this calorie target as the daily goal while logging food intake.
- Calorie BurnEstimate activity calories separately and compare them with this daily expenditure.
- BMI CalculatorCheck the height-and-weight screening category alongside calorie estimates.