Select your gender, enter your age, weight, and height in metric or imperial units, and choose a formula. The calculator instantly estimates your Basal Metabolic Rate in kcal and kJ per day, plus your BMI, giving you the calories your body needs at complete rest.
Free BMR calculator – no sign‑up
Calculate Your Basal Metabolic Rate in Seconds
Find out how many calories your body burns at complete rest. Enter your age, gender, height, and weight to see your BMR, understand your minimum energy needs, and plan your diet accordingly – all free, private, and instant.
Understand Your Body’s Minimum Energy Requirement
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform life‑sustaining functions at complete rest. It accounts for 60–70% of your total daily energy expenditure. Knowing your BMR is the foundation for any effective diet or fitness plan — whether you want to lose weight, gain muscle, or simply maintain a healthy lifestyle. This calculator uses the widely accepted Mifflin‑St Jeor equation, providing a personalized estimate based on your age, gender, height, and weight. It’s fast, free, and completely private.
What Is a BMR Calculator?
A BMR calculator is a free online tool that estimates your basal metabolic rate — the amount of energy (calories) your body burns in a day while at complete physical and mental rest. You enter your age, gender, height, and weight, and the calculator applies a scientifically validated formula to produce your BMR. The most common and accurate formula is the Mifflin‑St Jeor equation. The calculator may also display your BMR in comparison to different activity levels (TDEE) to give context to your daily calorie needs. It’s an essential tool for nutritionists, fitness coaches, and anyone taking control of their health.
How to Use the BMR Calculator
Enter Your Body Metrics
Provide your age, gender, height, and weight. These are the only inputs needed for the Mifflin‑St Jeor formula.
Receive Your BMR Instantly
Your BMR appears immediately. It represents the calories you’d burn if you lay in bed all day.
Understand Your Daily Needs (Optional)
Scroll down to see how your BMR translates into total daily energy expenditure (TDEE) at various activity levels, helping you plan meals and workouts – no sign‑up required.
How the BMR Calculator Determines Your Rate
The calculator uses the Mifflin‑St Jeor equation, considered the most accurate BMR formula for the general population. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161. The tool then provides your daily calorie needs at rest. It also shows how your BMR compares to TDEE at different activity levels, using standard multipliers (1.2 for sedentary, up to 1.9 for very active). All computations happen in your browser — your body data stays private.
Mifflin‑St Jeor Formula
BMR (M) = 10W + 6.25H – 5A + 5
BMR (F) = 10W + 6.25H – 5A – 161
W = weight in kg, H = height in cm, A = age in years. This formula is widely validated.
Key Features of This BMR Calculator
Instant, Accurate BMR
Uses the Mifflin‑St Jeor equation, the gold standard for resting metabolic rate estimation.
TDEE Overview
See how your daily calorie needs change with activity — from sedentary to very active — in one clear chart.
Personalized Nutrition Baseline
Use your BMR to build a calorie deficit for weight loss or a surplus for muscle gain safely.
Private & Secure
All body data stays on your device. Nothing is ever uploaded or shared.
Benefits of Knowing Your BMR
- ✅ Tailored weight management – create a calorie deficit or surplus based on your actual metabolic rate, not a guess
- ✅ Avoid metabolic slowdown – eating too few calories can lower your BMR; this tool helps you find a safe minimum
- ✅ Informed meal planning – design a diet that supports your goals without unnecessary restrictions
- ✅ Track changes over time – as you lose weight or gain muscle, your BMR shifts; recalculate to stay on target
- ✅ Understand your body – learn how age, gender, and body composition influence your metabolism
BMR vs. TDEE: What’s the Difference?
BMR (Basal Metabolic Rate)
The calories your body needs to maintain basic life functions — breathing, circulation, cell production — in a completely rested state.
TDEE (Total Daily Energy Expenditure)
BMR multiplied by an activity factor. This is the total number of calories you burn in a day, including movement, exercise, and digestion.
Using Both Together
Your BMR is your baseline. You should never consistently eat below your BMR for extended periods. Your TDEE is the number you eat to maintain, increase, or decrease weight.
How Age, Gender, and Muscle Affect Your BMR
BMR naturally declines about 1–2% per decade after age 20, largely due to loss of muscle mass. Men typically have a higher BMR than women because they carry more lean tissue. Even at the same weight and height, a more muscular person will burn more calories at rest. The calculator accounts for age and gender in the formula, but cannot directly measure muscle mass. For a more refined picture, combine this result with body fat percentage and consider professional metabolic testing.
Common BMR Formulas Compared
Mifflin‑St Jeor
The most accurate for the general population. The calculator uses this formula as the default.
Harris‑Benedict
An older formula that tends to overestimate BMR by about 5% in some populations. Still used in some clinical settings.
Katch‑McArdle
Requires body fat percentage. More accurate if you know your lean body mass, but this calculator uses Mifflin‑St Jeor for broader applicability.
Using Your BMR to Plan Your Diet
To lose weight safely, aim for a daily calorie intake between your BMR and your TDEE. A common approach is to multiply your BMR by 1.2 (sedentary) and then create a deficit of 300–500 calories. Never drop below your BMR for extended periods without medical supervision. For weight gain, add 300–500 calories to your TDEE. The calculator provides these rough figures; for a precise plan, combine it with our Calorie Calculator.
Can You Increase Your BMR?
Yes — primarily by increasing lean muscle mass. Strength training 3–4 times per week can raise your BMR over time. Other factors like eating enough protein, staying hydrated, and getting quality sleep also support a healthy metabolism. However, age‑related decline is normal. The calculator provides a snapshot; recalculate periodically to see the effect of your fitness efforts.
Example BMR Calculation
A 40‑year‑old woman, 5’6″ (168 cm), 150 lbs (68 kg). Her BMR according to Mifflin‑St Jeor is: (10 × 68) + (6.25 × 168) – (5 × 40) – 161 = 680 + 1050 – 200 – 161 = 1,369 calories/day. This is the minimum energy her body needs at complete rest. If she is moderately active, her TDEE would be about 1,369 × 1.55 ≈ 2,122 calories. The calculator provides these numbers clearly, helping her make informed dietary choices.
How Often Should You Recalculate Your BMR?
Recalculate whenever your weight changes by 5–10 pounds, or if your activity level shifts significantly. As you lose fat and gain muscle, your body composition changes, and so does your metabolic rate. The calculator makes it easy to update your numbers and stay on track.
Factors That Influence Basal Metabolic Rate
- ⚖️ Body weight and height
- 📅 Age
- 🚻 Gender
- 💪 Muscle mass
- 🧬 Genetics
- 🌡️ Body temperature and climate
- 🩺 Hormones (thyroid, etc.)
- 💊 Medications
Detailed BMR Scenario
Scenario: Male, 30 years, 6’0″ (183 cm), 200 lbs (90.7 kg).
- ✅ Mifflin‑St Jeor BMR: (10 × 90.7) + (6.25 × 183) – (5 × 30) + 5 = 907 + 1143.75 – 150 + 5 ≈ 1,906 kcal
- ✅ Sedentary TDEE (×1.2): ~2,287 kcal
- ✅ Moderately Active TDEE (×1.55): ~2,954 kcal
- ✅ This person should not drop below ~1,900 calories for extended periods.
Who Can Use This BMR Calculator?
- 🏋️ Weight‑loss seekers – find the lowest safe calorie intake to avoid metabolic damage
- 💪 Bodybuilders & athletes – base bulking or cutting plans on actual energy expenditure
- 👩⚕️ Healthcare & nutrition professionals – calculate baseline energy needs for clients
- 🎓 Students – learn how metabolism and energy balance work
- 📋 Anyone managing their health – understand the foundation of their daily calorie requirements
Key Metabolism Terms
- Basal Metabolic Rate (BMR)
- The minimum number of calories your body needs to sustain vital functions in a resting state.
- TDEE
- Total Daily Energy Expenditure — your BMR multiplied by an activity factor to reflect your lifestyle.
- Mifflin‑St Jeor Equation
- A highly accurate formula for estimating BMR, derived from a large population study.
- Resting Metabolic Rate (RMR)
- Similar to BMR, but measured under less strict conditions; often used interchangeably.
Tips for Using Your BMR Effectively
- Never consistently eat below your BMR — it can slow metabolism and cause muscle loss.
- Use your BMR to set a safe calorie floor and build your diet around whole, nutrient‑dense foods.
- Recalculate BMR after significant weight changes to keep your calorie targets accurate.
- Combine BMR knowledge with our Calorie Calculator for a full TDEE breakdown.
- Remember that BMR is an estimate; listen to your body and adjust based on real‑world results.
Advantages of This BMR Calculator
- ✅ 100% free – no sign‑up, no ads
- ✅ Instant, accurate BMR using Mifflin‑St Jeor
- ✅ Visual TDEE overview for all activity levels
- ✅ Easy metric/imperial unit support
- ✅ Works on any device
- ✅ Private – your body data never leaves your device
Limitations of BMR Estimates
The Mifflin‑St Jeor equation is a population‑based formula and may not perfectly reflect your individual metabolism. It does not directly measure muscle mass, body fat percentage, or hormonal status. For clinical or competitive purposes, consider a metabolic test. Always consult a healthcare professional before starting a very low‑calorie diet.
Accuracy of Results
The Mifflin‑St Jeor equation is widely considered the most accurate BMR formula for the general population, with a typical error margin of about 10%. For most people, it provides an excellent starting point for calorie planning.
Security and Privacy
All calculations are performed locally in your browser. No age, height, weight, or personal information is ever transmitted, stored, or shared. You can use the tool offline after the page loads.
Mobile‑Friendly Design
The BMR calculator is fully responsive. Use it on your smartphone, tablet, or desktop — all inputs, charts, and results adapt seamlessly to any screen size.
Frequently Asked Questions
What is a good BMR number?
There’s no universal “good” BMR, as it depends on your size, age, and gender. A higher BMR generally means you burn more calories at rest. The average BMR for adults ranges from about 1,200 to 2,000 calories per day.
Is BMR the same as RMR?
BMR (Basal Metabolic Rate) is measured under stricter conditions (complete rest, fasting) while RMR (Resting Metabolic Rate) is slightly more relaxed. They are often used interchangeably and the values are very close.
Why does my BMR decrease with age?
Because muscle mass tends to decrease with age (sarcopenia), and muscle burns more calories than fat. Regular strength training can help mitigate this decline.
Can I eat less than my BMR to lose weight faster?
It’s not recommended. Eating below your BMR for extended periods can cause muscle loss, nutritional deficiencies, and a slowed metabolism. Aim for a moderate calorie deficit based on your TDEE, not below your BMR.
Which BMR formula is most accurate?
The Mifflin‑St Jeor equation is widely considered the most accurate for the general population and is the formula used by this calculator.
Is my personal data safe?
Absolutely. All calculations are local. No data is ever sent to a server or stored.
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Conclusion: Know Your Metabolism, Master Your Health
Your BMR is the baseline of your energy needs. Understanding it gives you a powerful tool for managing weight, optimizing performance, and maintaining a healthy lifestyle. Use this calculator to find your number, then build a plan that works for you — all for free and in total privacy.
Ready to Discover Your BMR?
Enter your age, height, and weight now – free, private, and instant.