BMR Calculator
Calculate the baseline calories your body burns entirely at rest.
This is what you burn functioning without any movement.
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate, frequently abbreviated as BMR, is the total number of calories that your body needs to perform life-sustaining basal functions over a 24 hour period. These basal functions include breathing, circulating blood, controlling body temperature, cell growth, brain and nerve function, and contraction of muscles.
Essentially, if you were to lie in a bed completely still for an entire day, your BMR is the exact number of calories your body would burn.
How The BMR Formula Works
While there are several equations used to estimate BMR (such as the Harris-Benedict equation), modern science widely favors the Mifflin-St Jeor equation for its superior accuracy across various body types and ages. Our BMR calculator relies strictly on Mifflin-St Jeor.
- Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Why is BMR Important?
Knowing your BMR is the very first critical step in organizing any diet strategy. It serves as your absolute baseline energy output.
You cannot effectively determine how many calories you need to consume to lose or gain weight without first understanding your BMR. Once you have this number, you apply an activity multiplier to figure out your total daily burned calories (TDEE). Medical boards universally agree that you should virtually never eat fewer calories than your BMR across a prolonged period, as doing so puts the body into a state of severe starvation resulting in muscle catabolism.
Factors that affect BMR
| Factor | Effect on BMR |
|---|---|
| Muscle Mass | Increases BMR. Muscle is highly metabolically active tissue. The more you have, the more calories you burn at rest. |
| Age | Decreases BMR over time, largely due to naturally decreasing muscle mass as humans get older. |
| Body Size | Increases BMR. Taller, heavier individuals require more baseline energy to sustain their organ architecture. |
| Genetics | Can slightly increase or decrease BMR based on minor hormonal deviations. |