AtlasCalcsUtility Calculation Suite
2026-09-15 8 min

TDEE Comparison Calculator

Compare TDEE across all activity levels and both engines: Mifflin vs Katch maintenance side by side, range width, and the honest rung picker.

Calculator

Gender
Units
Age
yrs
Full years
Height
in
Barefoot standing height
Weight
lbs
Morning scale weight
Activity
Body fat
%
Adds the Katch column; blank keeps Mifflin only
Results update live as you type
Status:Mifflin 2,557 kcalKatch 2,563 kcalSpan 1,154 kcal

Comparison Results

TDEE (Moderate, Mifflin)2,557 kcal/day
Katch column2,563 kcal/day
Engine gap+6 kcal
Lifestyle span1,154 kcal/day

Maintenance Matrix (kcal)

ActivityMifflinKatch
Sedentary1,9801,984
Light2,2682,273
Moderate (you)2,5572,563
Heavy2,8462,852
Athlete3,1343,141

Recommendations

  • ▸At moderate: Mifflin maintenance 2,557 kcal vs Katch 2,563 (gap +6)
  • ▸Engines agree within shouting distance — anchor on either and spend accuracy efforts on honest rung selection instead
  • ▸Lifestyle span here is 1,154 kcal — rung honesty still outweighs engine choice

Results

Normal

TDEE

2,557 kcal

Moderate maintenance via Mifflin

Engine Gap

+6 kcal

Katch minus Mifflin at your rung

Span

1,154 kcal

Sedentary-to-athlete lifestyle range

Katch TDEE

2,563 kcal

Lean-mass maintenance at your rung

Mifflin and Katch (with measured fat) each scale across all five factors. Engine gaps reflect composition; rung gaps reflect lifestyle — read them separately.

Visualizations

Mifflin TDEE by Activity (kcal)

1,980Sedentary
2,268Light
2,557Moderate
2,846Heavy
3,134Athlete

Katch TDEE by Activity (kcal)

Engines at Your Rung

Mifflin2,557kcal

Formula

Two resting philosophies times five lifestyles produce the ten-cell maintenance matrix. Engine columns reveal composition truth; activity rows reveal lifestyle truth; your honest cell sits at their intersection.

Matrix: {Mifflin, Katch} x {1.2, 1.375, 1.55, 1.725, 1.9}

Alternative Form

Engine gap = Katch cell - Mifflin cell at your rung

Variables

SymbolNameUnitDescription
Matrix10 maintenance cellskcal2 engines x 5 rungs
Engine gapColumn differencekcalKatch minus Mifflin at one rung
SpanRow rangekcalAthlete minus sedentary, Mifflin column
CellYour maintenancekcalHonest rung x trusted engine

Explanation

Rows and columns separate the two great uncertainties: lifestyle (which you report) and composition (which you measure). Reading them independently stops rung errors from masquerading as equation errors and vice versa.

Derivation

Mifflin and Katch BMRs each scale by the five factors. Gap = Katch-Mifflin per rung (constant ratio, so gap scales with rung). Span = Mifflin x (1.9-1.2).

Step-by-Step Calculation

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

Step 1

Compute both resting engines.

Mifflin from stats; Katch from lean mass when fat known
Mifflin:1,650 kcal
Katch:1,653 kcal
Intermediate: Two philosophies of rest: demographic vs tissue
Result: Resting pair priced for scaling
Step 2

Scale each engine across five rungs.

TDEE = engine x 1.2-1.9
Cells:5 x 2 matrix
Intermediate: Ten maintenance numbers from one body
Result: Full matrix from 1,980 to 3,134 kcal
Step 3

Read your cell honestly.

Your rung x your engine
Cell:Moderate = 2,557 kcal
Intermediate: Rung from logs, engine from composition
Result: Your maintenance = 2,557 kcal
Step 4

Measure the engine gap.

Gap = Katch cell - Mifflin cell
Gap:+6 kcal
Intermediate: Composition signal isolated from lifestyle
Result: Engines differ by 6 kcal here
Step 5

Measure the lifestyle span.

Span = athlete - sedentary (Mifflin)
Span:1,154 kcal
Intermediate: Same engines, different lives
Result: Lifestyle swings 1,154 kcal — rung honesty dominates
Step 6

Commit to one cell.

Anchor rung x trusted engine
Cell:Moderate
Intermediate: At moderate: Mifflin maintenance 2,557 kcal vs Katch 2,563 (gap +6)
Result: Engines agree within shouting distance — anchor on either and spend accuracy efforts on honest rung selection instead
Final Answer
2,557 kcal

Worked Examples

See how the calculator works with different scenarios.

Scenario

A 30-year-old man, 175 cm, 70 kg, 15% fat, moderate.

Inputs

Stats:175 cm / 70 kg / 15%
Activity:Moderate

Calculation

Mifflin BMR 1648.8, Katch BMR 1655.2. Moderate cells: 2556 vs 2566 — gap +10. Span: 1979 to 3133 (Mifflin).

Result

Cells 2,556 vs 2,566; span 1,154

Interpretation

Average composition, tiny engine gap — rung choice is the entire decision here.

Understanding Your Result

Your Result: TDEE: 2,557 kcal

Typical range: Engine gaps typically ±150; rung spans 900-1,400. Cells range from sedentary-Mifflin floors to athlete-Katch ceilings.

What This Means

The complete maintenance matrix: five rungs, two engines, your highlighted cell, engine gap, lifestyle span — every maintenance conversation in one table.

Why It Matters

Single-number TDEE hides its own uncertainty. The matrix displays both axes of doubt so plans carry the right humility in the right places.

Professional Interpretation

Choose engine by composition evidence, rung by logged behavior, then plan from the intersecting cell. Document both choices — future stalls get audited against them.

Two-axis uncertainty

Median thinking

Recommendations

  • •Measure fat to unlock the full matrix
  • •Gaps over 150 kcal deserve an engine decision
  • •Spans over 1,000 demand rung honesty
  • •Plan from one cell, reference the matrix
  • •Re-run matrix with every phase change

Educational Content

Introduction

The TDEE Comparison Calculator builds your full maintenance matrix: Mifflin and Katch engines across all five activity rungs. Compare everything — then commit to one honest cell.

Concept Explanation

Maintenance has two independent uncertainties worth separating: how you live (rows) and what you are made of (columns). The matrix prices each axis so neither hides behind the other.

Applications

▸Settling engine vs rung debates
▸Coaching transparent target selection
▸Auditing stalled plans by axis
▸Teaching maintenance uncertainty
▸Second opinions with full context
▸Phase-change recalibration

Benefits

  • •Ten cells from one body
  • •Engine gap quantified per rung
  • •Span exposes lifestyle leverage
  • •Graceful missing-data behavior
  • •Your cell highlighted

Limitations

  • •Estimates on both axes
  • •Katch column needs honest fat
  • •Rung honesty still required
  • •Snapshot matrix per run

Best Practices

  • •Enter measured fat for both columns
  • •Highlight with logs, not hopes
  • •Screenshot the matrix per phase
  • •Revisit quarterly
  • •Trust gaps over gut feelings

Common Misconceptions

Myth: One TDEE fits all contexts.
Truth: Cutting, maintaining, and bulking interrogate different cells; deloads and seasons move rungs. The matrix is a map, not a monument.
Myth: Engine gaps mean broken math.
Truth: Gaps mean different assumptions meeting different bodies. A 400 kcal gap on a bodybuilder is information, not malfunction.
Myth: More precision beats better inputs.
Truth: A honest rung with Mifflin beats a fantasy rung with Katch every time. Inputs first, equations second.

Practical Tips

  • •Circle your cell and date it in training logs
  • •Re-check the gap after each DEXA or cut phase
  • •When torn between rungs, eat the lower for two weeks
  • •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

Planning from the max cell
Athlete-Katch is the matrix maximum, not your maintenance, unless both describe you. Max-cell planning is surplus by spreadsheet.
Ignoring a 400+ engine gap
Huge gaps are composition diagnoses demanding engine commitment, not shrugs. Pick the honest engine and note why.
Freezing one matrix all year
Cuts move mass, seasons move rungs, training moves both. Quarterly re-runs keep the map matched to territory.
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:

Published engines: Mifflin and Katch exact coefficients.
Standard rungs: Five population-average factors.
Honest fat: Katch column needs measured %.
Metric internals: Imperial converts before math.
Rounded cells: Whole-kcal matrix entries.

Limitations

Be aware of these limitations when using this calculator:

Estimate matrix: Ten estimates, zero measurements.
Shared blind spots: Both engines miss meds, hormones, illness.
Snapshot cells: One-day inputs per run.
Rung coarseness: Five rows cannot fit every life.

Frequently Asked Questions

Answers to common questions about this calculator.

Mifflin or Katch TDEE — which should I use?
Average builds: either (gaps run small). Muscular or very lean with measured fat: Katch. Soft or unknown composition: Mifflin. The gap row above grades your specific case.
Why compare across activity levels too?
Because rung errors (±280) triple engine gaps (±90). The matrix keeps the bigger uncertainty visible so it gets the honesty it deserves.
What does a negative engine gap mean?
Katch below Mifflin: softer-than-average composition at your weight. Trust Katch if fat is measured — it is correctly pricing quiet tissue.
How do I pick my cell?
Rung from two weeks of logs plus step averages; engine from composition evidence. Intersect them, screenshot it, validate by trend.
What is TDEE?
Total Daily Energy Expenditure — every calorie burned in 24 hours: basal metabolism (60-75%), food digestion TEF (~10%), daily movement NEAT (15-30%), and deliberate exercise (5-10%). Eating at TDEE holds weight steady.
How is TDEE calculated?
Estimate BMR (usually Mifflin-St Jeor), then multiply by an activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 heavy, 1.9 athlete. The product is maintenance.
What is NEAT and why does it matter?
Non-Exercise Activity Thermogenesis — walking, standing, chores, fidgeting. It varies 200-800+ kcal/day between people and is the most adjustable TDEE lever after formal exercise.
How accurate are TDEE estimates?
Within about 10-15% for most people when activity is honestly rated. Validate by eating at the estimate 2-4 weeks: stable weight confirms it, drift corrects it.
How do I use TDEE to lose weight?
Eat 250-500 kcal below TDEE for 0.5-1 lb weekly loss, keep protein high and lift to protect muscle, and never hold intake below your BMR floor for long.
How do I use TDEE to gain muscle?
Eat 250-350 kcal above TDEE with progressive resistance training and 1.6-2.2 g/kg protein. Bigger surpluses mostly accelerate fat gain, not muscle.
How often should I recalculate TDEE?
Every 4-8 weeks while changing, or per 10-15 lbs. Smaller bodies burn less, so yesterday maintenance becomes today surplus silently.

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

Maintenance matrix
2 engines x 5 rungs of TDEE cells.
Engine gap
Katch minus Mifflin at one rung.
Honest cell
Logged rung x evidenced engine.
Span
Athlete minus sedentary in one column.
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.

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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Page Information

Last Updated:

2026-09-15

Version:

2.0.0

License:

Free to use for educational and professional purposes.