Basal Metabolic Rate (BMR) is the energy your body needs at rest to maintain vital functions. It depends on age, sex, height, weight, and lean mass.

Which BMR formula is most accurate?

For most people, Mifflin-St Jeor performs well. If you know your body-fat percentage, Katch-McArdle can be more personalized because it uses lean body mass.

Total Daily Energy Expenditure (TDEE) is an estimate of your daily calorie needs based on your BMR and activity level. It is BMR multiplied by an activity factor.

BMR Calculator | Free Basal Metabolic Rate & TDEE

Welcome to the My Medicine Advisor BMR Calculator — the fastest, most accurate, and mobile-friendly tool for estimating your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Whether your goal is weight loss, weight gain, or weight maintenance, understanding your BMR is the first step to mastering your metabolism.

BMR Calculator

Estimate your Basal Metabolic Rate (BMR) using Mifflin-St Jeor, Revised Harris-Benedict, or Katch-McArdle (if body-fat % known). Optionally estimate daily calories (TDEE). This is educational, not medical advice.

Units Metric (kg, cm) US/UK (lb, ft/in)

Sex Male Female

Age 10–99 years

Height 100–250 cm

Weight 30–250 kg

Body fat (optional) Needed for Katch-McArdle (LBM-based) accuracy

Formula Mifflin-St Jeor (default) Revised Harris-Benedict Katch-McArdle (needs body-fat %)

Show daily calorie estimate (TDEE) Activity level

Your BMR

Mifflin-St Jeor

— kcal/day

≈ — kJ/day

Estimated daily calories (TDEE)

Moderate — 1.55

— kcal/day

Guidance only. Adjust for goals and monitor changes.

Mild loss (~−10%): — kcal

Loss (≈−500 kcal): — kcal

Gain (≈+300 kcal): — kcal

What is BMR?

Your Basal Metabolic Rate (BMR) is the energy your body needs at rest to sustain vital functions like breathing and circulation. It depends on age, sex, height, weight, and lean mass.

Formulas we use

Mifflin-St Jeor: widely used for general populations.
Revised Harris-Benedict: alternative based on height, weight, age, sex.
Katch-McArdle: uses lean body mass; requires body-fat %.

Disclaimer: This tool is educational and not a substitute for professional advice.

Show formulas

Mifflin-St Jeor (kcal/day)
Male: 10×kg + 6.25×cm − 5×age + 5
Female: 10×kg + 6.25×cm − 5×age − 161

Revised Harris-Benedict (kcal/day)
Male: 13.397×kg + 4.799×cm − 5.677×age + 88.362
Female: 9.247×kg + 3.098×cm − 4.330×age + 447.593

Katch-McArdle (kcal/day)
370 + 21.6×LBM(kg), where LBM = kg × (1 − body-fat%/100)

TDEE ≈ BMR × activity factor

This calculator is for education only and does not diagnose, treat, or prescribe. Always consult a licensed professional.

Disclaimer: This tool is for educational purposes only and not a substitute for medical advice. Always consult your healthcare provider for personalized guidance.

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to function at rest. Even if you stayed in bed all day, your body would still require energy for vital functions such as:

Breathing
Blood circulation
Brain activity
Hormone production
Cell repair

Your BMR accounts for 60–75% of daily calorie burn. The rest comes from physical activity and thermic effect of food (calories burned digesting food).

Key factors affecting BMR:

Age: BMR decreases with age.
Sex: Men often have higher BMR than women due to more lean muscle mass.
Height & weight: Larger bodies burn more energy.
Muscle vs. fat: Muscle tissue burns more calories than fat.
Hormones & genetics: Thyroid, genetics, and overall metabolic health influence BMR.

Why You Need a BMR Calculator

Understanding your BMR helps you:

Lose weight safely: Create a calorie deficit without under-eating.
Gain lean muscle: Know how much to eat above maintenance.
Maintain your weight: Balance calorie intake with output.
Personalize fitness goals: Tailor diet and workouts to your unique metabolism.
Improve health awareness: Track changes in metabolism over time.

By using the My Medicine Advisor BMR Calculator, you get instant insights into how your body uses energy, backed by scientifically validated formulas.

How Does the BMR Calculator Work?

Our calculator uses three globally recognized methods:

1. Mifflin-St Jeor Equation (default, most accurate for general population)

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) – 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) – 5 × age – 161

2. Revised Harris-Benedict Equation (older but widely used)

Men: BMR = 13.397 × weight (kg) + 4.799 × height (cm) – 5.677 × age + 88.362
Women: BMR = 9.247 × weight (kg) + 3.098 × height (cm) – 4.330 × age + 447.593

3. Katch-McArdle Formula (best for athletes with known body fat %)

BMR = 370 + (21.6 × Lean Body Mass in kg)
Lean Body Mass = weight × (1 – body fat % ÷ 100)

From BMR to TDEE: Daily Calorie Needs

Your TDEE (Total Daily Energy Expenditure) is BMR × activity factor:

Sedentary (little/no exercise): 1.2
Lightly active (1–3 days/week): 1.375
Moderately active (3–5 days/week): 1.55
Very active (6–7 days/week): 1.725
Extra active (physical job + training): 1.9

👉 Example: A 70 kg, 175 cm, 30-year-old male with moderate activity:

BMR ≈ 1665 kcal/day
TDEE ≈ 2580 kcal/day

This means he needs ~2580 kcal daily to maintain his weight.

BMR Calculator & Fitness Goals

Weight Loss: Aim for ~500 kcal deficit/day for ~0.5 kg weekly loss.
Weight Gain: Add ~300–500 kcal surplus/day for lean mass gain.
Maintenance: Match calorie intake to TDEE.

⚠️ Warning: Never go below 1200 kcal/day (women) or 1500 kcal/day (men) without medical supervision.

Internal Health Tools for Complete Tracking

Combine the BMR Calculator with our other tools for a 360° health profile:

BMI Calculator — know your body mass index category.
Pregnancy Due Date Calculator — track pregnancy timelines.
Symptom Checker — understand symptoms in context (educational).
AI Prescription Checker — decode your medicine labels.
Pill Identifier — identify tablets by imprint, shape, or color.

External Authority References

BMR vs. RMR: What’s the Difference?

BMR (Basal Metabolic Rate): Strict lab measurement under perfect rest.
RMR (Resting Metabolic Rate): Easier to measure, slightly higher than BMR.

Our calculator provides BMR, but for practical purposes, BMR and RMR are often used interchangeably.

How Accurate is the BMR Calculator?

Mifflin-St Jeor: ±10% accuracy for most adults.
Katch-McArdle: Best for those with body fat % data.
Reality check: Lifestyle, stress, and sleep also impact calorie needs.

The calculator gives a scientific baseline — but real-world tracking ensures accuracy.

Practical Uses of BMR Knowledge

Diet planning: Set calorie targets.
Athletic performance: Fuel training appropriately.
Medical context: Monitor metabolic changes with thyroid, diabetes, or hormonal issues.
Weight management apps: Many apps use BMR as a foundation for recommendations.

Frequently Asked Questions (FAQ)

Why should I calculate my BMR?

To understand your body’s calorie needs and set realistic fitness goals.

Which formula is best?

Mifflin-St Jeor is best for most people; Katch-McArdle is better if body fat % is known.

Can exercise increase my BMR?

Yes — building lean muscle raises resting metabolism.

Does age lower BMR?

Yes. Metabolism slows with age due to muscle loss and hormonal shifts.

How do I calculate TDEE?

TDEE = BMR × activity factor (1.2–1.9).

Can diet lower BMR?

Extreme dieting can slow metabolism over time. Focus on balanced nutrition.

What’s the difference between kcal and kJ?

1 kcal ≈ 4.184 kJ. Our calculator shows both.

Is this tool safe for kids?

No. These formulas are validated for adults.

How often should I recalculate BMR?

Every time your weight changes significantly (±5 kg) or every 3–6 months.

Is this medical advice?

No. This is an educational calculator only. Consult professionals for personal care.

The My Medicine Advisor BMR Calculator empowers you to understand your metabolism, estimate daily calorie needs, and set achievable health goals. Pair it with our other tools like the BMI Calculator, Symptom Checker, and Prescription Checker for a complete educational health toolkit.

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