2026-09-15 9 min

BMR Calculator

Estimate basal metabolic rate with Mifflin-St Jeor, Revised Harris-Benedict, or Katch-McArdle, then scale to TDEE across five activity levels with loss and gain targets.

Calculator

Gender

Units

Age

yrs

Full years

Height

Barefoot standing height

Weight

lbs

Morning scale weight

Body fat

Needed for Katch-McArdle; estimate or scan

Formula

Activity

Results update live as you type

Status:BMR 1,650 kcalTDEE 2,557 kcalMifflin-St Jeor

BMR Results

BMR (Mifflin-St Jeor)1,650 kcal/day

TDEE2,557 kcal/day

Hourly burn68.7 kcal/h

Lose ~1 lb/week2,057 kcal

Gain leanly2,857 kcal

TDEE Ladder (this BMR)

Activity	Factor	Calories
Sedentary (little or no exercise)	x1.20	1,980 kcal
Light (exercise 1-3 times/week)	x1.375	2,268 kcal
Moderate (exercise 4-5 times/week)	x1.55	2,557 kcal
Heavy (daily or intense exercise)	x1.725	2,846 kcal
Athlete (intense exercise 6-7 times/week)	x1.90	3,134 kcal
Lose ~1 lb/week	TDEE-500	2,057 kcal
Gain leanly	TDEE+300	2,857 kcal

Recommendations

▸At moderate activity, maintenance sits near 2,557 kcal — eat there to hold, 2,057 to lose about a pound weekly, 2,857 to gain leanly
▸You entered body fat, so compare Katch-McArdle above — with known composition it usually beats weight-only equations
▸Weigh daily, judge 2-4 week trends, and recalculate after every 10-15 lbs of change

Results

Normal

BMR

1,650 kcal

Mifflin-St Jeor resting estimate

TDEE

2,557 kcal

Moderate (exercise 4-5 times/week) maintenance

Hourly

68.7 kcal/h

Resting burn per hour, sleep included

Per-kg

23.6 kcal/kg

Metabolic intensity per kilogram

Floor-Ceiling

1,980 to 3,134 kcal

TDEE span from sedentary to athlete activity

Mifflin-St Jeor suits most adults; Revised Harris-Benedict cross-checks; Katch-McArdle wins when body fat is known. All three run here so you can compare instead of guessing.

Visualizations

TDEE by Activity (kcal)

1,980sedentary

2,268light

2,557moderate

2,846heavy

3,134athlete

BMR vs Adult Range

1,650kcal

8002,600

BMR Share of TDEE

Resting64.5%

Resting vs Total Burn

BMR1,650kcal

Formula

Three validated resting equations run side by side: Mifflin-St Jeor (1990, best general accuracy), Revised Harris-Benedict (Roza-Shizgal 1984, the modernized classic), and Katch-McArdle (lean-mass based, best when body fat is known). TDEE multiplies the chosen BMR by the standard 1.2-1.9 activity factors.

Mifflin-St Jeor: M 10W + 6.25H - 5A + 5; F 10W + 6.25H - 5A - 161

Alternative Form

Revised HB: M 88.362 + 13.397W + 4.799H - 5.677A; F 447.593 + 9.247W + 3.098H - 4.33A; Katch: 370 + 21.6 x LBM

Variables

Symbol	Name	Unit	Description
BMR	Basal metabolic rate	kcal/day	Resting burn for vital functions
W / H / A	Weight, height, age	kg / cm / yrs	Equation inputs in metric
LBM	Lean body mass	kg	Weight x (1 - body fat/100), Katch only
TDEE	Total expenditure	kcal/day	BMR x activity factor 1.2-1.9
Hourly	Resting rate	kcal/h	BMR / 24

Explanation

Weight dominates every equation because tissue costs energy; height adds frame; age subtracts the slow muscle loss of aging; the Katch variant swaps all three proxies for measured lean mass when available.

Derivation

Mifflin M: 10W+6.25H-5A+5; F: 10W+6.25H-5A-161. Revised HB M: 88.362+13.397W+4.799H-5.677A; F: 447.593+9.247W+3.098H-4.33A. Katch: 370+21.6xLBM. TDEE = BMR x {1.2, 1.375, 1.55, 1.725, 1.9}.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Normalize weight and height to metric.

kg = lbs / 2.20462; cm = in x 2.54

Age:adult years

Intermediate: Metric pair ready for the equations

Result: Analysis inputs normalized to kg and cm

Step 2

Apply the selected resting equation.

Mifflin-St Jeor

Formula:Mifflin-St Jeor

Intermediate: Weight, height, age (and lean mass for Katch) enter with fitted coefficients

Result: BMR = 1,650 kcal/day

Step 3

Scale resting burn by the activity factor.

TDEE = BMR x factor

Activity:Moderate (exercise 4-5 times/week)

Intermediate: 1,650 x factor = 2,557

Result: TDEE = 2,557 kcal/day

Step 4

Derive hourly and per-kg intensities.

Hourly = BMR / 24; per-kg = BMR / weight

Hourly:68.7 kcal/h

Per-kg:23.6 kcal/kg

Intermediate: Sleep costs roughly 8 x hourly; tissue intensity benchmarks

Result: 68.7 kcal every resting hour

Step 5

Read the full activity ladder.

Five rungs from x1.2 to x1.9 on this BMR

Floor:1,980 kcal

Ceiling:3,134 kcal

Intermediate: Same body, different life: a 1,100+ kcal lifestyle span

Result: Maintenance lives between 1,980 and 3,134

Step 6

Set goal rungs off maintenance.

Lose: TDEE - 500; gain: TDEE + 300

Lose:2,057 kcal

Gain:2,857 kcal

Intermediate: 500 kcal x 7 = 3,500 kcal, about a pound of fat

Result: At moderate activity, maintenance sits near 2,557 kcal — eat there to hold, 2,057 to lose about a pound weekly, 2,857 to gain leanly

Final Answer

1,650 kcal

Worked Examples

See how the calculator works with different scenarios.

Scenario

A 30-year-old man, 69 in (175.3 cm), 154 lbs (69.9 kg), 15% fat, Mifflin, moderate.

Inputs

Age:30

Height:69 in

Weight:154 lbs

Formula:Mifflin

Activity:Moderate

Calculation

BMR = 10x69.9 + 6.25x175.3 - 5x30 + 5 = 699 + 1095.6 - 150 + 5 = 1649.6, rounds 1650. Hourly = 68.7. TDEE = 1650 x 1.55 = 2557.

Result

BMR about 1,650 kcal, TDEE about 2,557 kcal

Interpretation

The reference adult male: maintenance near 2,557, loss near 2,057, lean gain near 2,857.

Understanding Your Result

Your Result: BMR: 1,650 kcal

Typical range: Adult BMR typically spans 1,200-2,200 kcal; TDEE 1,600-3,800. Hourly resting burn runs 50-90 kcal; per-kg intensity 20-26 kcal/kg for most adults.

What This Means

A resting-plus-activity energy dossier: BMR from your chosen equation, TDEE at your activity, hourly and per-kg intensities, the sedentary-to-athlete span, and loss/gain rungs with guardrails.

Why It Matters

Every calorie plan — cut, maintain, bulk — is arithmetic on top of BMR. A trusted resting number plus the activity ladder turns dieting from guessing into bookkeeping.

Professional Interpretation

Prescribe from TDEE, never BMR alone, and keep deficits above the BMR floor. When equations disagree by more than 10%, trust the lean-mass one if fat is measured, Mifflin otherwise.

Why three equations

The 60-75% rule

Recommendations

•Eat at TDEE to hold, TDEE-500 to lose, TDEE+300 to gain
•Never deficit below the BMR floor without supervision
•Recompute every 10-15 lbs of weight change
•Compare formulas when body fat is known
•Validate against 2-4 week weight trends

Educational Content

Introduction

The BMR Calculator estimates your resting calorie burn with three validated equations and scales it across five activity levels. Stats in — BMR, TDEE ladder, hourly rate, and goal calories out.

Concept Explanation

Your body spends most of its energy just staying alive. Equations fitted to thousands of lab measurements predict that cost from weight, height, age, and optionally lean mass — then activity factors complete the daily picture.

Applications

▸Setting maintenance calories honestly

▸Sizing deficits that spare muscle

▸Planning lean bulks without excess fat

▸Comparing equation agreement

▸Adjusting targets as weight changes

▸Pre-consultation numbers for clinicians

Benefits

•Three equations, one screen, no guessing
•Full five-rung TDEE ladder included
•Goal rungs with BMR-floor guardrail
•Hourly and per-kg intensities free
•Engine-backed math shared with our API

Limitations

•Equations estimate; calorimetry measures
•Outlier physiques need lean-mass equations or labs
•Activity factors are population averages
•Illness, meds, and hormones shift real burn

Best Practices

•Default to Mifflin unless fat is measured
•Log intake honestly for two weeks first
•Pick activity by training log, not aspiration
•Re-test quarterly while changing weight
•Trust trends over any single computation

Common Misconceptions

Myth: Starvation mode stops fat loss.

Truth: Adaptation slows loss 10-30% but never stops physics. Plateaus come from smaller bodies burning less plus creeping intake — both fixable.

Myth: Small frequent meals stoke metabolism.

Truth: Meal frequency does not move daily expenditure; totals and protein do. Eat on whatever schedule you sustain.

Myth: Cardio is the BMR lever.

Truth: Resistance training plus protein protects the tissue that sets BMR; cardio spends calories today but builds little resting burn.

Practical Tips

•Run all three formulas once to learn your spread
•Anchor protein at 1.6-2.2 g/kg before cutting calories
•Add 100 kcal NEAT (a daily walk) before cutting 100 kcal of food
•Weigh and measure in the morning before food for repeatable inputs
•Re-run the numbers after every 10-15 lbs of weight change
•Validate any estimate against 2-4 weeks of weight-trend data

Common Mistakes

Picking athlete activity for 3 gym days

Athlete means 6-7 intense sessions plus physical work. Overstated activity is the top reason maintenance estimates overshoot — be honest one rung lower.

Ignoring the Katch option when fat is known

A measured 12% and an assumed 20% describe different engines. If you paid for the scan, use the equation that reads it.

Setting and forgetting for a year

A body 20 lbs lighter burns ~100-150 kcal less daily. Stale targets silently become surpluses — refresh quarterly.

Using goal weight instead of current weight

Equations describe the body you have, not the one you want. Current weight sets today's burn; goal weight enters only when planning the next phase.

Confusing BMR with maintenance

BMR is the resting floor. Eating at BMR while active is an automatic deficit — multiply by activity (TDEE) before setting intake.

Assumptions

This calculator makes the following assumptions to provide estimates:

Healthy adult range: Equations validated roughly ages 18-80 at non-extreme weights.

Stable composition: Snapshot math; recomposition between measures is invisible.

Honest activity: Factors assume the labeled training frequency plus matching NEAT.

Metric internals: Imperial converts at 2.54 and 2.20462 before equations.

Rounded outputs: BMR to 0.1, TDEE table to whole calories.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: 10-15% individual error is normal; labs measure, equations guess.

Factor coarseness: Five activity rungs cannot capture every lifestyle precisely.

No hormonal modeling: Thyroid, menopause, and medications move real burn off-formula.

Single-day view: Illness, sleep debt, and cold exposure swing daily burn.

Frequently Asked Questions

Answers to common questions about this calculator.

Which BMR formula is most accurate?

Mifflin-St Jeor for the general population (within 10% for about 70% of adults). With measured body fat, Katch-McArdle usually wins, especially for lean or muscular people.

Why do three equations give different numbers?

Each was fitted to different populations with different proxies. A 3-8% spread is normal; the median of agreeing equations is a fine working number.

Should I use Katch-McArdle without a DEXA?

Only with a trustworthy body-fat estimate (skinfolds, smart scale trend). A bad fat guess makes Katch worse than Mifflin, not better.

Does BMR include exercise?

No — BMR is zero-activity baseline. Multiply by 1.2-1.9 for lifestyle (the TDEE ladder above) before comparing against what you eat.

What is BMR?

Basal Metabolic Rate is the calories your body burns at complete rest to run vital functions — breathing, circulation, brain, and cell repair. It is typically 60-75% of total daily expenditure and the floor every calorie plan builds on.

What is the difference between BMR, RMR, and TDEE?

BMR is measured under strict lab conditions (fasted, rested, thermoneutral). RMR is measured under looser conditions and reads a touch higher. TDEE adds all activity, digestion, and movement on top — TDEE is your maintenance calories.

How accurate are BMR equations?

Mifflin-St Jeor lands within 10% for roughly 70% of adults. Outliers — very muscular, very lean, or obese bodies — do better with lean-mass equations (Katch-McArdle, Cunningham) or lab indirect calorimetry.

Can I eat below my BMR?

Brief dips are fine, but chronic intake far below BMR costs muscle and triggers metabolic adaptation that can suppress expenditure 10-30%. Keep deficits moderate, protein high, and resistance training in.

How do I raise my BMR?

Build muscle (the durable lever), eat enough protein, sleep 7-9 hours, and move daily. Each pound of muscle adds only about 6 kcal/day at rest — BMR grows through tissue plus the activity that tissue enables.

How often should I recalculate BMR?

Every 4-8 weeks while weight changes, or after each 10-15 lbs lost or gained. Smaller bodies burn less, so targets must follow the body down and up.

Related Calculators

Explore more calculators related to this topic.

Related Guides

Deepen your understanding with these educational resources.

Metabolism Basics

BMR, TDEE, and where your calories actually go.

Setting Calories for Fat Loss

From TDEE to deficit without muscle loss.

Protein and Strength While Dieting

Keep the engine while shrinking the chassis.

Glossary

Technical terms used in mortgage calculations explained in plain language.

Mifflin-St Jeor: 1990 weight-height-age equation; best general accuracy.
Revised Harris-Benedict: 1984 Roza-Shizgal update of the 1919 classic.
Katch-McArdle: Lean-mass equation: 370 + 21.6 x LBM.
Activity factor: 1.2-1.9 multiplier converting BMR to TDEE.
BMR: Basal Metabolic Rate: resting calorie burn for vital functions.
TDEE: Total Daily Energy Expenditure: BMR plus all activity and digestion.
Lean body mass: Weight minus fat mass; the engine room equations like Katch use.
Metabolic adaptation: Down-regulation of expenditure during prolonged dieting beyond what tissue loss predicts.

Authoritative References

Trusted sources and standards referenced by this calculator.

Academy of Nutrition and Dietetics — Energy expenditure guidance ACSM — Metabolism and body composition resources PubMed — Predictive equation literature (Mifflin, Harris-Benedict, Cunningham, Owen) FAO/WHO/UNU — Schofield human energy requirements (1985) CDC — Finding a healthy weight and activity guidance MedlinePlus — Metabolism and weight management

Applicable Standards

Mifflin-St Jeor (AJCN 1990)Harris-Benedict original (1919) and Roza-Shizgal revision (1984)FAO/WHO/UNU Schofield requirements (1985)

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Last Updated:

2026-09-15

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.