What Is BMR?
Your Basal Metabolic Rate is the minimum number of calories your body needs to function at rest. Think of it as the cost of keeping the lights on. Your heart beats, your lungs expand, your brain processes information, your cells repair themselves — all of that takes energy, measured as BMR.
BMR makes up the largest piece of your total daily calorie burn, typically 60 to 75 percent. Everything else — walking, exercising, digesting food, even fidgeting — adds on top of this baseline.
How BMR Differs From TDEE
People often confuse BMR with TDEE. BMR is just the resting component. TDEE includes BMR plus everything else: exercise, daily movement, and the energy cost of digesting food. If BMR is your car idling in the driveway, TDEE is the fuel you actually burn during the whole trip.
Use the TDEE calculator if you want the full picture. Use BMR if you just need to know your baseline.
What Affects Your BMR
Several factors influence your BMR. Some you can control, some you cannot.
Muscle mass — Muscle tissue burns more calories at rest than fat tissue. This is the single biggest controllable factor. More muscle means a higher BMR.
Age — BMR tends to decrease about 1 to 2 percent per decade after age 20, mostly due to muscle loss. Strength training can offset most of this decline.
Genetics — Some people naturally have faster metabolisms. Two people of the same size and age can have different BMRs.
Hormones — Thyroid function, sex hormones, and stress hormones all affect your metabolic rate. This is why medical conditions can shift your BMR outside the expected range.
The Mifflin-St Jeor Formula
This calculator uses the Mifflin-St Jeor equation, the most widely validated BMR formula for the general population.
Male BMR: 10 × weight(kg) + 6.25 × height(cm) − 5 × age(y) + 5
Female BMR: 10 × weight(kg) + 6.25 × height(cm) − 5 × age(y) − 161
The formula was developed in 1990 and confirmed in multiple studies as the most accurate option for everyday use.
Frequently Asked Questions
For most adults, BMR falls between 1,200 and 2,500 calories per day. Men tend to have higher BMRs than women due to greater muscle mass and average body size.
Yes. Building muscle through strength training is the most effective way. Eating enough protein and getting quality sleep also help maintain a healthy metabolic rate.
Yes. As you lose weight, your BMR decreases because there is less body mass to maintain. This is why calorie targets need adjusting every 10 to 15 pounds.
Similar but not identical. BMR is measured under stricter conditions (complete rest, fasted). RMR is slightly higher and easier to measure. For practical purposes, the difference is small enough to ignore.
Disclaimer: This calculator is for informational purposes only and does not constitute medical advice.
