The BMR calculator estimates your Basal Metabolic Rate — the calories your body burns at rest to keep you alive — using the Mifflin-St Jeor equation. For men: 10×weight(kg) + 6.25×height(cm) − 5×age + 5. For women the same formula minus 161. Enter your age, sex, height and weight for an instant, private estimate.
BMR Calculator at a Glance
- What it does: estimates the calories your body burns at complete rest over 24 hours.
- How long it takes: Under a second — the math runs on your own device.
- Cost: Nothing — free forever, no sign-up.
- Where it works: Any browser — phone, tablet, laptop or desktop.
What Is the BMR Calculator?
Your BMR, or Basal Metabolic Rate, is the number of calories your body would burn if you stayed in bed all day just breathing, circulating blood and keeping your organs running. It is the engine-idle figure of your metabolism and the foundation of almost every nutrition plan.
This BMR calculator uses the Mifflin-St Jeor equation, the formula preferred by most dietitians and sports nutritionists today because it tends to be more accurate than the older Harris-Benedict equation for modern populations. You enter a few simple details and get your resting calorie estimate in about a second.
Knowing your BMR helps you understand the lowest sensible number of calories you should eat in a day and, combined with your activity level, the number you need to maintain, lose or gain weight. It is one of the most useful figures in fitness and weight management.
How to Use the BMR Calculator
Using the tool takes only a few seconds. Here is the whole routine, step by step:
- Choose Metric or Imperial.
- Select your sex.
- Enter your age, height and weight.
- Press Calculate to see your BMR in calories per day.
- Multiply by an activity factor (or use our TDEE calculator) for daily maintenance calories.
How the BMR Calculator Works: Formula and Method
The Mifflin-St Jeor equation was published in 1990 and quickly became the standard BMR formula because it matched measured metabolic rates more closely than its predecessors.
For men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
For women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
If you use pounds and inches, the calculator converts them automatically. The result is kilocalories per day at complete rest.
BMR (men) = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
BMR (women) = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
Worked Example with the BMR Calculator
Let us work through a typical example:
- A 30-year-old man weighs 80 kg and is 180 cm tall.
- 10×80 = 800; 6.25×180 = 1125; 5×30 = 150.
- BMR = 800 + 1125 − 150 + 5 = 1780 calories per day.
- That means his body burns roughly 1780 kcal before any movement is added.
Swap in your own numbers and remember that BMR is a strong estimate, not a laboratory measurement.
When Should You Use the BMR Calculator?
Here are the everyday situations where this tool earns its place:
- Setting a calorie baseline. BMR tells you the floor. Eating persistently below it is hard on energy and hormone health, so it anchors any sensible diet.
- Planning weight loss or gain. Once you know maintenance (BMR × activity), a modest deficit or surplus becomes easy to set.
- Understanding metabolism. Seeing how age, height and weight shift the number helps explain why two people can eat differently.
- Fitness coaching. Trainers use BMR to give clients realistic, personalised nutrition targets rather than one-size-fits-all numbers.
Common Mistakes to Avoid With the BMR Calculator
BMR is straightforward, but these slips can distort the picture:
- Confusing BMR with TDEE. BMR is rest only; TDEE includes movement. Most people need TDEE, not BMR, to decide how much to eat.
- Using the wrong sex constant. The +5 and −161 terms matter. Select the option that matches your biology to keep the estimate accurate.
- Guessing your weight. A difference of 5 kg shifts BMR by about 50 kcal, so use a recent scale reading.
- Treating it as exact. Formulas estimate within roughly 5–10%. Body composition, hormones and genetics all play a role.
- Eating at BMR long term. Staying at or below BMR for too long can sap energy and slow progress. Use it as a baseline, not a daily target.
Who Is the BMR Calculator For?
The BMR calculator is for anyone planning nutrition — people losing weight, building muscle, maintaining a healthy lifestyle, or simply curious about their metabolism. Coaches, dietitians and carers also use it as a quick starting point.
No science background is needed. The page explains every term, and the form only asks for age, sex, height and weight.
Quick Reference Table
| Factor | Activity Level |
|---|---|
| 1.2 | Sedentary (little or no exercise) |
| 1.375 | Lightly active (1–3 days/week) |
| 1.55 | Moderately active (3–5 days/week) |
| 1.725 | Very active (6–7 days/week) |
| 1.9 | Extra active (physical job or twice-daily training) |
Multiply your BMR by the matching factor to estimate TDEE — the calories you burn in an average day.
How We Verify the BMR Calculator
Every calculator uses a recognised formula (Mifflin-St Jeor for BMR) and is checked against worked examples before publication. We update pages when guidance evolves and note the review date at the top.
If a reader reports an inconsistency, we reproduce the calculation, fix the issue and note the update.
Questions People Also Ask About the BMR Calculator
These are the conversational, intent-based questions people ask search engines and AI assistants about BMR calculator — each answered directly so it can appear in an AI Overview or featured snippet.
Informational queries
What is my BMR?
Basal Metabolic Rate is the number of calories your body needs to perform basic life functions while at complete rest, such as breathing and circulation.
What is BMR?
Basal Metabolic Rate is the number of calories your body needs to perform basic life functions while at complete rest, such as breathing and circulation.
How-to and navigational queries
How is BMR calculated?
Basal Metabolic Rate is the number of calories your body needs to perform basic life functions while at complete rest, such as breathing and circulation.
How does the bmr calculator work?
It uses the Mifflin-St Jeor equation, which is widely regarded as more accurate than the older Harris-Benedict formula for most adults.
What formula does the bmr calculator use?
It uses the Mifflin-St Jeor equation, which is widely regarded as more accurate than the older Harris-Benedict formula for most adults.
How do I calculate BMR?
Basal Metabolic Rate is the number of calories your body needs to perform basic life functions while at complete rest, such as breathing and circulation.
Decision and advice queries
How many calories do I burn at rest?
The BMR calculator estimates your Basal Metabolic Rate — the calories your body burns at rest to keep you alive — using the Mifflin-St Jeor equation. For men: 10×weight(kg) + 6.25×height(cm) − 5×age + 5. For women the same formula minus 161. Enter your age, sex, height and weight for an instant, private estimate.
What is a normal BMR?
It varies widely with size, age and sex, but many adults fall between roughly 1300 and 2000 calories per day. Larger, younger and more muscular people tend to have a higher BMR.
Does muscle increase BMR?
Yes. Lean muscle tissue is metabolically active, so people with more muscle generally burn more calories at rest than the formula's simple estimate.
How accurate is the bmr calculator?
It uses the Mifflin-St Jeor equation, which is widely regarded as more accurate than the older Harris-Benedict formula for most adults.
Can I trust the bmr calculator result?
It uses the Mifflin-St Jeor equation, which is widely regarded as more accurate than the older Harris-Benedict formula for most adults.
Transactional and tool queries
Is the bmr calculator free to use online?
Yes. It is completely free, with no sign-up, no subscription, no trial and no limit on how many times you use it. Open the page and start calculating.
Best free BMR calculator online?
Yes. It is completely free, with no sign-up, no subscription, no trial and no limit on how many times you use it. Open the page and start calculating.
Frequently Asked Questions About the BMR Calculator
What is BMR?
Basal Metabolic Rate is the number of calories your body needs to perform basic life functions while at complete rest, such as breathing and circulation.
What formula does this BMR calculator use?
It uses the Mifflin-St Jeor equation, which is widely regarded as more accurate than the older Harris-Benedict formula for most adults.
What is a normal BMR?
It varies widely with size, age and sex, but many adults fall between roughly 1300 and 2000 calories per day. Larger, younger and more muscular people tend to have a higher BMR.
Does muscle increase BMR?
Yes. Lean muscle tissue is metabolically active, so people with more muscle generally burn more calories at rest than the formula's simple estimate.
How is BMR different from TDEE?
BMR covers rest only; TDEE, or Total Daily Energy Expenditure, multiplies BMR by an activity factor to include movement and exercise.
Does BMR decrease with age?
Typically yes, partly because lean mass often declines with age. Staying active and resistance training help limit that drop.
Can I eat below my BMR to lose weight?
Eating slightly below maintenance is normal for weight loss, but staying at or below BMR long term can harm energy, hormones and adherence. Aim for a moderate deficit.
Why do men and women have different formulas?
The sex constants (+5 vs −161) reflect average differences in body composition between men and women, improving the estimate across populations.
How accurate is the Mifflin-St Jeor equation?
For most adults it lands within about 5–10% of measured resting metabolic rate, which is accurate enough for everyday nutrition planning.
Does this BMR calculator store my data?
No. The calculation runs in your browser; age, height and weight are never uploaded or saved.
Is the BMR Calculator free to use?
Yes. It is completely free, with no sign-up, no subscription, no trial and no limit on how many times you use it. Open the page and start calculating.
Do I need to create an account?
No. There is no account system and no login. The tool works the moment the page loads.
Does it save or store the numbers I enter?
No. Everything runs inside your own browser. The values you type are never sent to a server, saved in a database, or shared with anyone. Close the tab and they are gone.
Can I use it on my phone or tablet?
Yes. The page is fully responsive and works smoothly on phones, tablets, laptops and desktop computers. There is no app to install.
Does it work offline?
Once the page has loaded, yes. The calculation happens in your browser, so it keeps working even without an internet connection.
How accurate is the result?
The arithmetic is exact and runs at full precision, with rounding only at the final display. The limitations come from the method itself and the numbers you enter, not from the calculator.
What units does it support?
Where both systems are offered, you can switch between metric (centimetres, kilograms) and imperial (feet, inches, pounds). Pick the one you have and the tool handles any conversions.
What formula does it use?
It uses the standard, widely accepted formula for this type of calculation, shown in the Formula section of the page. Nothing is hidden or improvised.
Why is my result slightly different from a manual calculation?
Almost always rounding order. The calculator keeps full precision until the end, whereas hand sums often round intermediate steps and drift by a decimal or two.
What happens if I enter an invalid value?
The form checks the allowed range and shows a short, friendly message. Correct the highlighted value and calculate again.
What if I leave a required field blank?
The calculator will ask you to complete the missing field before working out a result.
Can it handle decimals and large numbers?
Yes. Decimals are accepted and a wide range of values is supported; results stay readable even at the extremes.
How fast will I get my answer?
Instantly, usually in under a second. Because the math runs on your device there is no server delay or loading spinner.
Can I bookmark or share the page?
Absolutely. Each calculator has its own clean URL, so you can bookmark it or share the link with anybody — it is free for everyone.
Is the result a medical diagnosis?
No. The BMR Calculator is an educational and planning tool, not a medical device. It gives a helpful estimate; decisions about your health should be made with a qualified professional.
Who writes and reviews the content?
Content is written and reviewed by the Calculator Converter Tool editorial team, who check both the formula and the plain-language explanation before publication.
Is the tool updated regularly?
Yes. Calculators are tested before release and re-reviewed as the library is updated. The 'Last updated' date at the top shows the most recent review.
Can I use it for work or professional tasks?
Many people use it as a quick, dependable aid during the working day. For important decisions, treat the result as a strong starting point and apply any required professional review.
Is it suitable for students and beginners?
Yes. Every field is labelled, the formula is shown, and there is a worked example on the page, so beginners and students can follow exactly what is happening.
Are there any hidden fees?
None. Free means free here — no trials, no premium tier, no surprise charges.
What should I do if I disagree with the result?
First double-check the values and the units you entered; that is the usual cause. If it still looks wrong, cross-check with a second method or, for health matters, consult a professional.
Does the page show its working?
The formula and a fully worked example are printed above the calculator, so you can follow every step if you want to understand how the answer was reached.
How do I report a bug?
If something looks wrong, please get in touch via the About Us page and describe the tool and the values you entered. We investigate reports and fix confirmed issues.
Does it work in dark mode?
Yes. Use the theme toggle in the header to switch between light and dark; the choice is remembered on your device.
Can I print my result?
The page is print-friendly. Use your browser's print function if you want to keep a paper copy for your records or an appointment.
Does it replace advice from a professional?
No. It is designed to inform and to support planning, not to replace the judgement of a doctor, dietitian, trainer or other qualified professional.
Final Thoughts on the BMR Calculator
Your BMR is the daily calorie cost of simply being alive. This calculator gives you that number quickly, privately and free with the formula shown so you can trust it. From there, TDEE and a sensible eating plan become much easier to build. If you want to go deeper on the topic, Academy of Nutrition and Dietetics is a dependable reference: Academy of Nutrition and Dietetics. We link to one trusted source per page and nothing more.
Five Practical Tips for Using the BMR Calculator
- Pair it with TDEE. BMR is the starting line; TDEE is the number most daily decisions should be based on.
- Recheck after big weight changes. Losing or gaining 5 kg shifts your BMR, so recalculate every few months.
- Don't chase precision you don't need. A 50-kcal estimate is plenty for planning real meals.
- Consider body composition. Muscle burns more energy at rest than fat, which a one-size formula only partly reflects.
- Use it to avoid under-eating. If a diet plan sits well below your BMR, treat that as a red flag.
None of this takes long, but together these habits turn a quick calculation into a dependable one — and that is usually the difference between a tool you use once and one you keep coming back to.