2026-09-15 8 min

Mifflin-St Jeor BMR Calculator

The gold-standard Mifflin-St Jeor equation in isolation: BMR, hourly burn, Mifflin-vs-world context, and the full TDEE ladder.

Calculator

Gender

Units

Age

yrs

Full years

Height

Barefoot standing height

Weight

lbs

Morning scale weight

Results update live as you type

Status:1,650 kcalvs Mifflin +0.0Mifflin-St Jeor

Mifflin-St Jeor Results

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

Hourly burn68.7 kcal/h

vs Mifflin+0.0 kcal (+0.0%)

Per-kg intensity23.6 kcal/kg

TDEE (moderate)2,557 kcal

TDEE Ladder (this BMR)

Activity	Factor	Calories
Sedentary	x1.2	1,980 kcal
Light	x1.375	2,268 kcal
Moderate	x1.55	2,557 kcal
Heavy	x1.725	2,846 kcal
Athlete	x1.9	3,134 kcal

Recommendations

▸Anchor here first — when other equations disagree, Mifflin plus measured-fat Katch settle most debates
▸Versus Mifflin (1,650 kcal): +0.0 kcal (+0.0%) — small gaps mean easy trust
▸Maintain near 2,557 kcal at moderate activity; start cuts there and keep them above the resting floor
▸Recalculate after every 10-15 lbs of weight change — equations follow mass faithfully

Results

Normal

BMR

1,650 kcal

Mifflin-St Jeor resting estimate

Hourly

68.7 kcal/h

Resting burn per hour

vs Mifflin

+0.0 kcal

Gap to the Mifflin-St Jeor cross-check (1,650 kcal)

Per-kg

23.6 kcal/kg

Tissue intensity benchmark

TDEE Mod.

2,557 kcal

Maintenance at moderate activity

Mifflin-St Jeor (1990) validated within 10% for about 70% of adults. The cross-check line shows Harris and Katch so agreement — not authority — earns trust.

Visualizations

This Equation vs Mifflin (kcal)

1,650Mifflin-St Jeor

1,650Mifflin

BMR vs Adult Range

1,650kcal

8002,600

BMR Share of Moderate TDEE

Resting64.5%

Formula

Mifflin-St Jeor (Mifflin et al., 1990) regressed resting burn on weight, height, and age in 498 subjects and validated tighter than every predecessor. The Academy of Nutrition and Dietetics endorses it for healthy adults — weight leads, height frames, age gently discounts.

M 10W + 6.25H - 5A + 5; F 10W + 6.25H - 5A - 161

Alternative Form

Hourly = BMR/24; TDEE = BMR x 1.2-1.9

Variables

Symbol	Name	Unit	Description
BMR	Mifflin-St Jeor resting burn	kcal/day	Equation output for your stats
Hourly	Resting rate	kcal/h	BMR divided by 24
Delta	Mifflin gap	kcal	This BMR minus Mifflin cross-check
TDEE	Maintenance	kcal/day	BMR x activity factor

Explanation

Ten per kilo, six-and-a-quarter per centimeter, minus five per year: each coefficient prices one tissue logic. The gender constants (+5/-161) absorb average composition differences in a single number.

Derivation

Fitted by least squares against indirect calorimetry; validation shows ~70% of predictions within 10% of measured. Cross-check: Revised HB typically within 3-5%, Katch diverges with composition.

Step-by-Step Calculation

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

Step 1

Normalize stats to metric.

kg = lbs / 2.20462; cm = in x 2.54

Equation:Mifflin-St Jeor

Intermediate: Weight, height, age ready; fat if the equation needs it

Result: Inputs normalized for Mifflin-St Jeor

Step 2

Apply the Mifflin-St Jeor equation.

M 10W + 6.25H - 5A + 5; F 10W + 6.25H - 5A - 161

BMR:1,650 kcal

Intermediate: Ten per kilo, six-and-a-quarter per centimeter, minus five per year: each coefficient prices one tissue logic. The gender constants (+5/-161) absorb average composition differences in a single number.

Result: BMR = 1,650 kcal/day

Step 3

Cross-check against Mifflin-St Jeor.

Delta = this BMR - Mifflin BMR

Mifflin:1,650 kcal

Intermediate: Gap +0.0 kcal (+0.0%)

Result: Agreement within 5% — anchor confidently

Step 4

Derive hourly and per-kg figures.

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

Hourly:68.7 kcal/h

Per-kg:23.6 kcal/kg

Intermediate: Same resting total, three lenses

Result: 68.7 kcal every resting hour

Step 5

Scale to moderate-activity maintenance.

TDEE = BMR x 1.55

TDEE:2,557 kcal

Intermediate: 1,650 x 1.55

Result: Maintain near 2,557 kcal

Step 6

Take the prescription.

Anchor, plan, recalculate per 10-15 lbs

Equation:Mifflin-St Jeor

Intermediate: Anchor here first — when other equations disagree, Mifflin plus measured-fat Katch settle most debates

Result: Versus Mifflin (1,650 kcal): +0.0 kcal (+0.0%) — small gaps mean easy trust

Final Answer

1,650 kcal

Worked Examples

See how the calculator works with different scenarios.

Scenario

A 30-year-old man, 175 cm, 70 kg.

Inputs

Age:30

Height:175 cm

Weight:70 kg

Calculation

BMR = 700 + 1093.75 - 150 + 5 = 1648.75, rounds 1648.8. Hourly = 68.7. TDEE moderate = 2556.

Result

BMR 1,649 kcal; hourly 68.7

Interpretation

The equation flagship case: every textbook starts here.

Understanding Your Result

Your Result: BMR: 1,650 kcal

Typical range: Adult outputs typically 1,000-2,400 kcal. Gaps within ±5% of Mifflin read as agreement; wider gaps carry the interpretation in the steps above.

What This Means

Your Mifflin-St Jeor resting burn with hourly rate, per-kg intensity, the Mifflin gap that grades trust, and the five-rung TDEE ladder.

Why It Matters

Single-equation fluency beats multi-equation confusion when a protocol, paper, or coach names this formula. Know exactly what it says about you — and where it disagrees with the field.

Professional Interpretation

Anchor plans on agreement across equations, investigate honest gaps (composition usually), and always name the equation on handoffs — same stats, different formula, different number.

Why the Mifflin gap leads

Equation loyalty vs evidence

Recommendations

•Compare against Mifflin before prescribing
•Start deficits from TDEE, floor at BMR
•Recalculate per 10-15 lbs of change
•Name the equation in notes and handoffs
•Validate against 2-4 week trends

Educational Content

Introduction

The Mifflin-St Jeor Calculator runs the single most trusted BMR equation in clinical nutrition. Stats in — gold-standard resting burn, hourly rate, cross-checks, and the TDEE ladder out.

Concept Explanation

Prediction beats tradition when the regression is better. Mifflin replaced Harris-Benedict in guidelines because newer data and better statistics simply predicted measured burn more accurately.

Applications

▸Running the named equation exactly

▸Translating protocols that cite it

▸Grading trust via the Mifflin gap

▸Teaching equation history hands-on

▸Second opinions on existing targets

▸Pre-consultation preparation

Benefits

•Exact published coefficients
•Mifflin cross-check built in
•Hourly and per-kg figures free
•Full TDEE ladder included
•Honest missing-data behavior

Limitations

•Single-equation lens by design
•Estimates, never calorimetry
•Population fit, individual error
•Inputs assumed honest and fresh

Best Practices

•Always read the Mifflin gap first
•Measure fat before trusting lean-mass variants
•Re-run with fresh weight monthly
•Note the equation name everywhere
•Confirm big gaps with trends

Common Misconceptions

Myth: One true BMR exists per person per day.

Truth: Even labs vary a few percent day to day. Equations add their own error — ranges and agreement beat false precision.

Myth: Newer equations obsolete older ones.

Truth: Each fits some population best. Mifflin leads generally, but Katch, Cunningham, and Schofield each win their home turf.

Myth: The ladder factor is exact.

Truth: Activity multipliers are population averages. Active-job lifters and fidgety NEAT monsters both live off-rung — validate by trend.

Practical Tips

•Screenshot the Mifflin gap for your records
•Re-run quarterly; equations age with inputs, not time
•Use the ladder rung matching your training log
•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

Quoting the number without the equation name

A bare 1,700 kcal means nothing across formulas. Name it every time: Mifflin 1,649 reads differently from Cunningham 1,809.

Planning from an equation that ignores your best data

Measured fat with a weight-only equation wastes information; unknown fat with Katch fabricates it. Match equation to data.

Forgetting age in multi-year comparisons

Five kcal yearly compounds: decade-apart numbers differ 50 kcal before anything else changes. Compare age-adjusted.

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 coefficients: Exact published constants, metric inputs.

Adult validation: Fitted on adult samples unless noted.

Honest inputs: Current weight, barefoot height, full years.

Metric internals: Imperial converts before equations.

Rounded display: BMR to 0.1, ladder to whole calories.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Individual error 10-15% is normal.

Single lens: One equation cannot see what it omits.

Static snapshot: One day inputs, one day output.

No clinical modeling: Illness, meds, hormones excluded.

Frequently Asked Questions

Answers to common questions about this calculator.

Why is Mifflin-St Jeor considered the best?

Its 1990 validation on 498 subjects showed tighter prediction than Harris-Benedict — within 10% for about 70% of people — earning endorsement from the Academy of Nutrition and Dietetics for healthy adults.

When should I not use Mifflin?

With measured body fat at the extremes (very lean athletes, high obesity), Katch-McArdle or Cunningham price composition better. Mifflin assumes average tissue blend.

What do the +5 and -161 mean?

Gender intercepts absorbing average composition differences: male physiology runs about 166 kcal above female at identical weight, height, and age.

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

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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: Resting equation featured on this page.
Cross-check: Mifflin gap grading trust in the featured number.
TDEE ladder: BMR scaled by 1.2-1.9 activity factors.
Missing-data guard: Lean-mass equations prompting for fat instead of guessing.
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.