CLINICAL BMR EQUATIONS • ZERO SIGNUP

Basal Metabolic Rate (BMR) Calculator

Calculate your baseline resting metabolic rate using the clinical Mifflin-St Jeor and Katch-McArdle equations. Instant, 100% private in-browser analysis.

Formula: Mifflin-St Jeor

1. Physical Profile

Step 1 of 2

Biological Sex

Age

28 years

Current Body Weight 175 lbs (79.4 kg)

lbs

Height 5 ft 10 in (178 cm)

I know my Body Fat % (Optional) Unlocks Katch-McArdle formula for lean mass precision

2. Smart Activity Wizard

Multiplier: 1.500

Daily Occupation (NEAT - Non-Exercise Activity)

Structured Exercise Sessions (EAT - Lifting / Cardio)

Desk Job (1.15 base) + 3–4 Workouts/wk (+0.25)

Calculates total energy expenditure without the 30% overestimation error of standard activity dropdowns.

Ideal Body Weight Matrix

Clinical reference benchmarks

Reference

Devine (1974) 161 lbs Medical standard

Robinson (1983) 156 lbs Modern clinical

Hamwi (1964) 166 lbs Rule of thumb

Max Muscular 172 lbs At 8-10% drug-free

Standard formulas estimate healthy body weight based on height and frame. Athletic individuals with high muscle mass naturally exceed these ranges without elevated adiposity.

Energy Anatomy (TDEE)

4-Part metabolic burn model

Breakdown

TDEE Component Split 2,350 kcal total

BMR (Basal)

1,720 kcal Coma/survival baseline

NEAT (Walking)

353 kcal Daily non-exercise steps

TEF (Digestion)

185 kcal Thermic cost of food

EAT (Training)

92 kcal Structured workouts

Peer-Reviewed BMR Formula Audit: Baseline BMR

Mifflin (1990) 1,720

Harris-B (1984) 1,768

Katch (LBM) 1,732

Daily Maintenance Output

2,350 kcal / day

Zero weight gain or loss baseline

Basal BMR 1,720 Coma rate

Clinical BMI 25.1 Normal

Hydration 2.8 L 95 oz / day

Select Desired Target Goal

Daily Calorie Target:

1,850 kcal/day (-500 kcal)

-150 kcal (Mild) -500 kcal -1,000 kcal (Max Safe)

Hybrid Deficit Engine

Cardio vs. Diet Tradeoff

Decide how your deficit is created: eat less food, burn more movement, or balance both.

Net Deficit: -500 kcal

Diet: 50% (-250 kcal)

Cardio: 50% (-250 kcal)

100% Kitchen 50 / 50 Hybrid Balance 100% Cardio

Daily Plate Target -250 kcal food

2,100 kcal to eat

You eat +250 kcal more food per day than a sedentary diet!

Preserved Food Allowance +1 large sweet potato, or +2 whole eggs on sourdough, or +55g oats with berries & honey.

Cardio & Step Target -250 kcal cardio

+4,800 extra daily steps

Target total: 10,800 steps/day (~2.4 miles)

Prescribed Cardio Modality ~28 min outdoor brisk walk (3.2 mph) or 18 min 8% incline treadmill walk at 3.0 mph.

The G-Flux (High Energy Flux) Advantage:

Clinical research shows combining moderate food restriction with daily steps produces the same fat loss rate with 42% less hunger, lower cortisol, and zero metabolic slowdown compared to starvation-only diets.

Goal Weight Timeline Simulator

Interactive metabolic projection & milestone roadmap

Projected: Jan 27, 2027

Target Goal Arrival -1.5 lbs / week pace

Jan 27, 2027

At 1,518 kcal/day, you will hit your goal of 152.0 lbs in 15 weeks!

Prescribed Intake 1,518 kcal / day

Target Goal Weight Step: ±1 lbs

lbs

Fat to Lose

22.5 lbs

12.8% of body weight

Estimated Duration

15.0 Weeks

~105 calendar days

Interactive Milestones:

*Assumes consistent weekly adherence at current prescribed deficit (1 lb fat ≈ 3,500 kcal / 7,700 kcal per kg). Weight fluctuates daily by 1–3% due to glycogen, hydration, and digestion.

ISSN Macronutrient Distribution

Protein anchored to bodyweight (1.0g/lb) to prevent muscle loss while cutting

1,850 kcal/day

Protein

175g

700 kcal (38%)

1.0g / lb bodywt

Fats

51g

462 kcal (25%)

Hormone health

Carbs

172g

688 kcal (37%)

Training energy

Meal Split:

(~44g P / 13g F / 43g C per meal)

Sync with logging apps or print a diet sheet

Sample Report →

Targets copied to clipboard!

Quick TDEE Calculator

PERSONAL METABOLIC REPORT • quicktdeecalc.com

Report ID: QTD-2026-105C

Issued: 21 October 2026

quicktdeecalc.com

01. Patient Anthropometrics & Baseline Biometrics

Your basic information and body composition overview.

Biological Sex

Male

Patient Age

28 years

Total Body Mass

49.9 kg (110 lbs)

Stature / Height

178 cm (5 ft 10 in)

Body Mass Index (BMI)

15.7 Underweight

Body Fat % & LBM

Standard Anthropometric

(No body fat % provided)

Activity Tier (Work)

Standing Work

On your feet most of the day

Exercise Frequency

0 workouts / week

No structured exercise

02. Daily Energy Expenditure Summary

Key metabolic values and your recommended daily target.

Basal Metabolic Rate (BMR)

1,452 kcal / day

Mifflin–St Jeor Equation

Total Daily Energy Expenditure (TDEE)

1,888 kcal / day

Maintenance (Activity Adjusted)

Suggested Daily Caloric Target

2,638 kcal / day

+750 kcal Surplus · Lean Mass Gain

Illustrative estimate — adjust based on observed weight trend and professional guidance.

03. Daily Macronutrient Targets (ISSN Partitioning)

Recommended macronutrient intake based on your selected plan.

Protein

14%

90 g / day

360 kcal

Supports muscle protein synthesis and recovery.

Dietary Fats

83%

242 g / day

2,178 kcal

Important for hormone production and overall health.

Carbohydrates

25 g / day

100 kcal

Primary energy source for daily activities and brain function.

Macro targets shown as entered; verify total energy before use. The sum of macro calories may not match your daily target.

04. 4-Component Energy Expenditure Matrix

Estimated contribution of each component to your TDEE.

Component	Details	Estimated Calories	% of TDEE (Approx.)
BMR (Basal Metabolic Rate)	Core energy for vital functions	1,452 kcal	77%
NEAT (Daily Movement)	Non-exercise activity (standing, walking, etc.)	283 kcal	15%
TEF (Thermic Effect of Food)	Energy used for digestion and processing food	264 kcal	14%
EAT (Exercise Activity)	Planned workouts / exercise	0 kcal	0%

Percentages are approximate and can exceed 100% due to overlapping and model-based estimates. Actual values vary by individual.

05. Goal Timeline & Physiological Projection

Estimated timeline based on your selected calorie target.

Starting Weight

49.9 kg (110 lbs)

Target Goal Weight

65.3 kg (144 lbs)

Projected Date

March 29, 2027

Estimated Duration

22.7 weeks (~159 days)

49.9 kg

65.3 kg

06. Clinical Notes & Professional Sign-off

Formulas used and important information.

Mifflin–St Jeor Equation

Used for BMR. Accurate and reliable for the general adult population (≈90% of people).

Activity-Adjusted Estimate

Combines your work style and exercise frequency to estimate total daily energy expenditure (TDEE).

Important

For adults only. Not medical advice. Seek a clinician's guidance before major dietary changes, especially if underweight or managing a medical condition.

Scientific Decomposition

The Four Metabolic Pillars of TDEE

Daily burn is not just workouts. Understanding where your body oxidizes energy is the key to escaping the 'wearable tracker fallacy' and establishing a predictable, sustainable calorie deficit.

Workouts account for only 5–10% of daily burn for most lifters.

65–70% of TDEE

Basal Metabolic Rate (BMR)

The involuntary vegetative energy required to sustain cellular survival at complete rest: brain activity, liver processing, kidney filtration, and heart contraction.

Formula basis Mifflin / Katch

15–20% of TDEE

Non-Exercise Activity (NEAT)

All movement outside deliberate workouts: pacing, posture, daily steps, typing, and fidgeting. NEAT is the primary metabolic differentiator between fast and slow metabolisms.

Highest variance Step Count Index

8–10% of TDEE

Thermic Effect of Food (TEF)

The metabolic cost of digesting, absorbing, and processing food. Dietary protein demands 20–30% of its caloric value just to metabolize, compared to 0–3% for fats.

Protein burn 20–30% TEF

5–10% of TDEE

Exercise Thermogenesis (EAT)

Deliberate athletic conditioning and resistance training. While critical for muscular retention and cardiovascular health, exercise accounts for a modest slice of total daily oxidation.

Gym sessions Lifting & Cardio

RESTING METABOLISM • CELLULAR BIOENERGETICS

Understanding Your Basal Metabolic Rate (BMR)

Basal Metabolic Rate accounts for 60% to 75% of the total energy an average human expends each day. Even in a state of complete muscular paralysis or coma, your body expends thousands of calories maintaining chemical gradients across cellular membranes, filtering blood through kidneys, producing bile, and regulating core internal body temperature.

Where Do BMR Calories Go?

Liver: ~27% of BMR (gluconeogenesis, detox, protein synthesis)
Brain: ~19% of BMR (continuous glucose & neurotransmitter turnover)
Skeletal Muscle: ~18% of BMR (protein turnover & ion maintenance)
Kidneys: ~10% of BMR (filtration & active electrolyte transport)
Heart: ~7% of BMR (continuous cardiovascular pumping)
Other Organs & Tissues: ~19% of BMR

How to Optimize Your BMR

Build & Retain Lean Tissue: Progressive overload resistance training stimulates myofibrillar hypertrophy.
Avoid Chronic Low-Calorie Starvation: Cyclic refeeds and diet breaks prevent thyroid T3 depression.
Prioritize Deep Sleep (7–9h): Poor sleep disrupts growth hormone pulse and elevates evening cortisol.
Ensure Adequate Iodine, Zinc & Selenium: Essential micronutrients for thyroid hormone conversion.

Evidence-Based Nutrition Answers

Frequently Asked Questions About TDEE & Energy Balance

Answers to common questions regarding metabolic calculations, safe deficits, muscle retention, and formula accuracy.

What is the difference between BMR and TDEE?

Basal Metabolic Rate (BMR) represents the absolute minimum energy required to keep your vital organs functioning at complete physical and emotional rest in a temperate environment. Total Daily Energy Expenditure (TDEE) takes your BMR and multiplies it by an activity factor to include the energy burned through daily movement, work, digestion, and structured exercise.

Which BMR formula is more accurate: Mifflin-St Jeor or Katch-McArdle?

Mifflin-St Jeor is the most reliable equation for general populations when body fat percentage is unknown, with an accuracy rate within 10% of indirect calorimetry. Katch-McArdle is superior for athletic, muscular, or lean individuals because it directly calculates BMR from Lean Body Mass (LBM), preventing underestimation in athletes or overestimation in obese individuals.

Can I safely eat below my BMR to lose weight faster?

Clinical nutritionists strongly advise against eating below your BMR for extended periods. Doing so forces your body into a state of severe biological conservation: thyroid hormone conversion drops, resting energy expenditure slows, hair and nail growth decelerates, and reproductive hormones decline.

Does building muscle increase my BMR significantly?

Yes, but moderately. One pound of skeletal muscle tissue burns approximately 6 kcal per day at rest, compared to about 2 kcal per pound of adipose tissue. While 10 pounds of muscle burns an extra 60 kcal/day at rest, the primary metabolic benefit of muscle lies in increased glycogen storage capacity, insulin sensitivity, and the elevated energy cost of training with greater mass.

Why does BMR decrease with age?

BMR declines by approximately 1% to 2% per decade after age 25–30. However, the majority of this decline is not an inevitable consequence of aging, but rather the result of age-related sarcopenia (loss of skeletal muscle mass) and a gradual reduction in daily physical movement (NEAT).