Resting energy estimate
Estimate calories used at complete rest and compare maintenance targets across common activity multipliers.
Use the defaults as an example or replace them with your measurements.
Method
Mifflin-St Jeor, revised Harris-Benedict, or Katch-McArdle
Practical context
Basal metabolic rate estimates the calories your body would use at complete rest. Compare Mifflin-St Jeor, revised Harris-Benedict, and Katch-McArdle results, then use an activity multiplier when you need a full daily calorie estimate.
BMR is the energy required to maintain essential processes such as breathing, circulation, temperature regulation, and cellular activity under standardized resting conditions. It does not include a normal day of walking, working, training, or digesting meals.
A BMR calculator estimates that resting requirement from measurable traits. It does not directly test metabolism, and a result should not be treated as a mandatory calorie intake.
Resting metabolic rate, or RMR, is measured under less restrictive conditions and is often slightly higher than strict BMR. Online calculators commonly use the terms loosely because both are estimates of resting energy needs.
TDEE is different. It begins with a resting estimate and includes activity. Use BMR to understand the resting component and TDEE to plan an initial maintenance intake.
Mifflin-St Jeor uses sex, age, height, and weight and is a practical default for most adults. Revised Harris-Benedict uses the same general inputs with different coefficients and offers a second population estimate.
Katch-McArdle uses estimated lean body mass and does not require age or sex. It can be useful when body fat percentage is known reasonably well, but a poor body fat estimate can make it less accurate rather than more personalized.
| Formula | Equation | Best use |
|---|---|---|
| Mifflin-St Jeor | 10w + 6.25h - 5a + sex constant | Practical general default |
| Revised Harris-Benedict | Sex-specific weight, height, and age coefficients | Alternative population estimate |
| Katch-McArdle | 370 + 21.6 x lean mass in kg | Lean-mass-based estimate |
Body size and lean mass are major contributors, while age, sex, genetics, hormones, health, and prolonged energy restriction can also affect resting expenditure. A formula captures only some of those relationships.
Rapid weight change, illness, pregnancy, medication, or a suspected metabolic condition deserves professional guidance rather than repeated calculator adjustments.
The activity table multiplies BMR by common activity factors to create rough maintenance-calorie estimates. Select a whole-week description rather than choosing the highest level because one workout feels difficult.
Track body weight and intake for several weeks to calibrate the estimate. Actual maintenance is the intake associated with a stable trend under your current activity pattern.
Questions people ask
