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Home›Health & Fitness›BMR Calculator

BMR Calculator

Basal Metabolic Rate (Mifflin-St Jeor)

Quick Answer — BMR

The BMR Calculator is a free online health & fitness tool that helps you basal metabolic rate (mifflin-st jeor). Enter your values above for instant, accurate results — no signup required. All calculations run privately in your browser.

Standard Formula Updated 2026
kg
70kg
20kg200kg
cm
170cm
50cm250cm
years
30years
0years100years

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Free forever Data stays on your device Works offline (PWA) Verified formulas

Maintained by: Sagar Sahni, Calc Labz  |  Review: formula checks, worked examples, and periodic updates

Use with care: Health outputs are informational estimates only and do not replace medical advice.

Need a correction? Contact us with the calculator name and the issue you found.

Formula & Worked Example

The math behind the BMR Calculator

Mathematical Formula

BMR = 10 \times W + 6.25 \times H - 5 \times A + S
**Mifflin-St Jeor Equation** (most accurate for modern populations): - **W** = Weight in kg - **H** = Height in cm - **A** = Age in years - **S** = Sex factor (+5 for males, −161 for females) - BMR represents the minimum calories your body burns at complete rest.

Step-by-Step Worked Example

For a **25-year-old female**, 165 cm, 60 kg: - BMR = 10 × 60 + 6.25 × 165 − 5 × 25 − 161 - BMR = 600 + 1031.25 − 125 − 161 - **BMR ≈ 1,345 kcal/day** - This means she burns ~1,345 calories just to stay alive.

Frequently Asked Questions

Common questions about the BMR Calculator

What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at absolute rest — just to keep your heart beating, lungs breathing, and brain functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity factor. TDEE is what you actually burn in a day including movement and exercise.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990) is considered the most accurate by the Academy of Nutrition and Dietetics. It is more accurate than Harris-Benedict (1919, revised 1984) and Katch-McArdle (which requires body fat %). Our calculator uses Mifflin-St Jeor.
Why does BMR decrease with age?
BMR drops ~2-3% per decade after age 30, primarily due to loss of muscle mass (sarcopenia) and hormonal changes. A 25-year-old man may have a BMR of 1,800 kcal, but the same person at 55 may have 1,550 kcal. Strength training helps preserve muscle mass and maintain a higher BMR.
Can I increase my BMR?
Yes. Build more muscle through resistance training (muscle burns more calories at rest than fat). Stay hydrated, get adequate sleep (7-9 hours), and eat enough protein (1.6-2g per kg). Crash dieting lowers BMR, so avoid extreme calorie restriction.
Should I eat my BMR calories if trying to lose weight?
Your calorie target should be TDEE minus 300-500, not BMR. Eating at BMR means a moderate deficit if you are active. Eating below BMR for extended periods can cause metabolic adaptation, muscle loss, and nutrient deficiencies. Minimum safe intakes: 1,200 kcal/day (women), 1,500 kcal/day (men).

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What is the BMR Calculator?

The BMR Calculator is a free online health & fitness tool that helps you basal metabolic rate (mifflin-st jeor). Built for accuracy and speed, this calculator uses verified formulas and provides instant results without requiring any signup or registration. All calculations run entirely in your browser, ensuring complete privacy — no personal data is ever sent to our servers.

How to Use the BMR Calculator

  1. Enter Weight: Enter your weight (in kg) in the input field. The calculator will validate your input automatically.
  2. Enter Height: Enter your height (in cm) in the input field. The calculator will validate your input automatically.
  3. Enter Age: Enter your age (in years) in the input field. The calculator will validate your input automatically.
  4. View Your Results: The BMR Calculator displays your results instantly in the output panel. You will see the primary result along with a detailed breakdown of secondary outputs. Scroll down for charts, interpretations, and expert advice.

Key Features

  • Instant BMR calculations with real-time updates
  • No signup, no registration — 100% free forever
  • All calculations happen in your browser — zero data sent to servers
  • Works offline as a Progressive Web App (PWA)
  • Mobile-friendly responsive design
  • Verified health & fitness formulas updated for 2026

Why Use Calc Labz BMR Calculator?

The Calc Labz BMR Calculator stands out because it combines accuracy with simplicity. Unlike other online calculators, we provide detailed breakdowns, step-by-step formulas, and actionable advice alongside your results. Our health & fitness calculators are regularly updated to reflect current rates, rules, and standards for India (2026). Whether you are a student, professional, or just need a quick calculation — Calc Labz delivers reliable results instantly.

Key Terms & Glossary

BMI
Body Mass Index — a screening tool that estimates body fat using weight and height (kg/m²).
BMR
Basal Metabolic Rate — the number of calories your body burns at complete rest to maintain vital functions.
TDEE
Total Daily Energy Expenditure — total calories burned per day including BMR, activity, and thermic effect of food.
Macros
Macronutrients: protein, carbohydrates, and fats — the three main nutrients that provide energy (calories).
Caloric Deficit
Consuming fewer calories than your TDEE, causing your body to use stored fat for energy, leading to weight loss.
Body Fat %
The percentage of your total body weight that is composed of fat tissue, as opposed to lean mass.

Sources & References

Our BMR Calculator uses formulas and guidelines from the following authoritative sources:

  • Mifflin-St Jeor et al. (1990) — AJCN
  • NIDDK — Calorie Calculator