Free BMR Calculator
Calculate your Basal Metabolic Rate, Resting Metabolic Rate (RMR), and daily calorie needs in under 30 seconds using the Mifflin-St Jeor equation.
- BMR
- RMR
- TDEE
- Weight-loss calories
What is basal metabolic rate (BMR)?
Your basal metabolic rate is the number of calories your body burns at complete rest to keep you alive, covering things like breathing, circulation, and brain function.
Think of BMR as your body's idle fuel cost, before any movement, exercise, or digestion. It usually makes up 60 to 70% of the calories you burn each day, which is why it is the foundation of any calorie or weight loss plan.
BMR vs RMR vs TDEE
BMR is calories burned at rest, RMR is nearly the same measured less strictly, and TDEE is your full daily burn including activity, which is the number you should base your diet on.
| Term | What it measures | How to use it |
|---|---|---|
| BMR | Calories burned at complete rest | Your metabolic floor. Do not eat below it. |
| RMR | Calories at rest, measured less strictly | Interchangeable with BMR for planning. |
| TDEE | Total daily burn including activity | Your real calorie target. Base your diet on it. |
BMR calculator for weight loss
To lose weight, eat 300 to 500 kcal below your TDEE, not below your BMR, which gives steady fat loss while protecting your muscle.
| Goal | What it does | Calories |
|---|---|---|
| Maintenance | Eat what you burn | TDEE |
| Mild loss | About 0.25 kg per week | TDEE - 300 |
| Steady loss | About 0.5 kg per week | TDEE - 500 |
| Muscle gain | Lean surplus | TDEE + 300 |
| Recomposition | Lose fat, keep muscle | Around TDEE, high protein |
A 500 kcal daily deficit gives roughly 0.5 kg of fat loss per week. The calculator above shows your exact weight loss, maintenance, and muscle gain calories once you enter your details.
How many calories do I burn at rest?
The calories you burn at rest are your BMR, typically 1,300 to 1,600 kcal a day for women and 1,600 to 2,000 kcal a day for men.
Most of this resting burn comes from your organs. The liver, brain, muscles, and kidneys together account for more than 70% of the energy your body uses while doing nothing at all. Enter your details above to see your own number.
How to calculate BMR
Calculate BMR with the Mifflin-St Jeor equation, which uses your weight, height, age, and sex.
Mifflin-St Jeor (recommended)
Men: (10 x kg) + (6.25 x cm) - (5 x age) + 5
Women: (10 x kg) + (6.25 x cm) - (5 x age) - 161
Harris-Benedict (revised)
Men: 88.362 + (13.397 x kg) + (4.799 x cm) - (5.677 x age)
Women: 447.593 + (9.247 x kg) + (3.098 x cm) - (4.330 x age)
Katch-McArdle (needs body fat %)
BMR = 370 + (21.6 x lean body mass in kg)
Worked example
30-year-old woman, 65 kg, 165 cm, Mifflin-St Jeor:
(10 x 65) + (6.25 x 165) - (5 x 30) - 161 = 1,370 kcal/day
Which BMR formula is most accurate?
The Mifflin-St Jeor equation is the most accurate for most adults, while Katch-McArdle is best if you know your body fat percentage.
| Formula | Best for |
|---|---|
| Mifflin-St Jeor | Most adults, recommended default |
| Harris-Benedict | Traditional clinical estimate |
| Katch-McArdle | When you know your body fat % |
BMR calculator for men
Men usually have a higher BMR than women of the same size because they carry more muscle and less essential body fat.
| Age | 70 kg / 175 cm | 80 kg / 175 cm | 90 kg / 175 cm |
|---|---|---|---|
| 25 | 1,788 kcal | 1,888 kcal | 1,988 kcal |
| 35 | 1,738 kcal | 1,838 kcal | 1,938 kcal |
| 45 | 1,688 kcal | 1,788 kcal | 1,888 kcal |
| 55 | 1,638 kcal | 1,738 kcal | 1,838 kcal |
BMR calculator for women
Women have a slightly lower BMR than men of the same size, reflected by the -161 term in the female Mifflin-St Jeor equation.
| Age | 55 kg / 163 cm | 65 kg / 163 cm | 75 kg / 163 cm |
|---|---|---|---|
| 25 | 1,332 kcal | 1,432 kcal | 1,532 kcal |
| 35 | 1,282 kcal | 1,382 kcal | 1,482 kcal |
| 45 | 1,232 kcal | 1,332 kcal | 1,432 kcal |
| 55 | 1,182 kcal | 1,282 kcal | 1,382 kcal |
Pregnancy, menopause, and thyroid conditions can shift your actual BMR beyond what any formula predicts.
What is a normal or average BMR?
A normal BMR is roughly 1,300 to 1,600 kcal for younger women and 1,600 to 2,000 kcal for younger men, falling gradually with age.
| Group | Average BMR | Average TDEE (moderate) |
|---|---|---|
| Women (20 to 40) | 1,300 to 1,600 kcal | 2,000 to 2,400 kcal |
| Men (20 to 40) | 1,600 to 2,000 kcal | 2,400 to 3,000 kcal |
| Women (40 to 60) | 1,200 to 1,500 kcal | 1,850 to 2,300 kcal |
| Men (40 to 60) | 1,500 to 1,900 kcal | 2,300 to 2,900 kcal |
| Athletes (any sex) | 1,700 to 2,400+ kcal | 3,000 to 4,500+ kcal |
How to increase your metabolism
The most effective way to increase your BMR is to build muscle with resistance training, supported by enough protein, sleep, and daily movement.
Resistance training
Building muscle is the most reliable way to raise your BMR for the long term.
Higher protein intake
Protein has a high thermic effect, so you burn more digesting it than carbs or fat.
Prioritise sleep
Poor sleep disrupts appetite hormones and lowers your effective metabolic rate.
Move more (NEAT)
Walking, standing, and fidgeting add up to a meaningful share of your daily burn.
Stay hydrated
Even mild dehydration slightly reduces how efficiently your body burns energy.
Common BMR mistakes
The most common BMR mistakes are dieting to your BMR instead of your TDEE, and not recalculating after you lose weight.
Dieting to your BMR
BMR is your floor. Always calculate TDEE and eat below that instead.
Eating below your BMR
It triggers muscle loss and metabolic slowdown within weeks.
Not recalculating after weight loss
Lose 10 kg and your BMR drops about 100 kcal, so your deficit shrinks.
Overestimating activity level
Most people pick a level too high, which inflates their calorie target.
Why Your BMR Can Fall During GLP-1 Weight Loss
If you are on a GLP-1 like Ozempic, Wegovy, Mounjaro or Zepbound and the scale has slowed down, a falling BMR is often part of the story, and it usually does not mean the medication has stopped working.
Quick refresher. Your BMR is what your body burns at rest just to keep the lights on, and it is not a fixed number. It moves with your size and your muscle. When you lose weight, there is simply less of you to power, so your BMR comes down with it. A smaller body burns fewer calories, even doing nothing all day.
Then there is the part that catches a lot of people off guard, called metabolic adaptation (you will also see it called adaptive thermogenesis). When you spend a long stretch eating well under what you used to, your body reads that as food being scarce and quietly dials down how much energy it spends. It is a survival feature, not a flaw. Hormones shift, and you tend to move a little less without realising it, less fidgeting, fewer trips up the stairs, that kind of thing. The result is that your resting burn can land lower than a formula would predict for your new weight.
Put those two together and you get the pattern almost everyone hits. The first few weeks fly by, then loss slows even though you feel like you are doing everything the same. On a GLP-1 this can be unsettling, because it is easy to assume the drug gave up on you. Usually it did not. Your appetite is still suppressed and you are still eating in a deficit. The deficit just got smaller, because the gap between what you eat and what you burn narrowed as your BMR dropped. That is arithmetic, not failure.
The good news is you have real say over how far your BMR falls, and it comes down to protecting the tissue that burns the most at rest, which is muscle. During fast weight loss, and especially on a GLP-1 when you are eating a lot less, some of what you lose can be muscle rather than fat, and losing muscle is exactly what drags your resting burn down even further. Two habits blunt that.
Keep your protein up
Getting enough protein every day (a common target is roughly 1.2 to 1.6 grams per kilogram of body weight) gives your body less reason to break down muscle for fuel. Not sure of your number? The macro calculator works it out for you.
Lift a few times a week
Resistance training tells your body to hold on to muscle while the fat comes off, which keeps more of your metabolism intact. You do not need anything fancy, just a couple of consistent sessions that get a bit harder over time.
None of this is a reason to panic. It just means your BMR from six weeks ago is not your BMR today, so it is worth running the calculator again at your current weight and rebuilding your targets from the fresh number. And if the stall drags on and you want to check whether it looks normal or is worth raising with your prescriber, that is exactly what the GLP-1 plateau analyzer is for. Your clinician knows your full picture, so always loop them in before you change your dose or your plan.
Think you've hit a plateau?
See whether your slowdown looks normal for where you are, and what actually gets things moving again.
Frequently asked questions
Frequently Asked Questions
Your BMR drops as you lose weight
The number above is true today. Six weeks and 5 kg from now it is not, which is why calorie targets quietly stop working and fat loss stalls. Calqulate Vitals keeps your weight, meals and doses on one timeline so your numbers stay current instead of going stale.
- Log a weight or meal in seconds
- Everything you log on one timeline
- Protein check on your meals
- Fat vs muscle trend (Premium)
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Tool Information
June 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.
About the authors
Meet Akabari
·Co-Founder, Calqulate.net