Is Mifflin–St Jeor better than Harris–Benedict?

Many modern apps prefer Mifflin–St Jeor for typical adults, but individual fit still varies.

Do I need to memorize coefficients?

No—use a vetted calculator; understanding inputs matters more.

Can I use it if muscular?

Equations approximate; very high muscle may need outcome-based adjustments.

Does keto change BMR?

Short-term shifts exist; long-term weight change still ties to average intake vs expenditure.

Is this medical advice?

No—educational overview only; clinicians guide clinical nutrition.

Where is it implemented here?

The homepage calculator uses Mifflin–St Jeor internally for BMR.

BMR & TDEE

Mifflin–St Jeor formula explained (BMR)

Mifflin–St Jeor is a regression equation that predicts resting energy expenditure from simple body measurements—fast, cheap, and good enough to start, then refine with data.

Why this formula exists

Researchers measured oxygen use in many people, then fitted an equation so apps can estimate BMR without a metabolic cart. It trades precision for accessibility.

What inputs do and why they matter

Weight and height

Larger bodies generally cost more energy to maintain at rest; height contributes to surface area and lean mass proxies.

Age and sex

Population trends show average lean mass and hormonal environments differ by age and sex—equations encode those averages, not destiny.

From BMR to TDEE in apps

After BMR, software multiplies by activity factors to approximate TDEE—see TDEE calculation.

Limitations (evidence-aware)

Elite athletes, certain illnesses, pregnancy, and atypical body composition can sit off the line. Use estimates as starting points, not verdicts.

What “good enough” looks like

Validation beats theory.

Food / context	Typical serving	Approx. kcal
Prediction says	2,600 maintenance	hypothesis
You track	2,350 stable	use 2,350

Values are rounded planning estimates—check labels for your brand.

Misunderstandings

Treating coefficients as biological laws.
Switching equations weekly instead of testing one pipeline.
Ignoring that activity errors dwarf equation differences.

Fitness planning

Pair formula literacy with BMR basics.

Educational use only

This guide summarizes general nutrition and energy-balance concepts. It is not medical advice, a diagnosis, or a substitute for care from a registered dietitian or physician—especially if you are pregnant, under 18, have an eating disorder history, or manage diabetes, heart disease, or other conditions.

Same topic cluster plus useful cross-links—built for crawl depth and readers exploring a goal end-to-end.

Deep dives: FAQ index · Weight-loss calculator · Keto macro calculator

Quick answers

Matches the FAQ structured data on this page.

Is Mifflin–St Jeor better than Harris–Benedict?: Many modern apps prefer Mifflin–St Jeor for typical adults, but individual fit still varies.
Do I need to memorize coefficients?: No—use a vetted calculator; understanding inputs matters more.
Can I use it if muscular?: Equations approximate; very high muscle may need outcome-based adjustments.
Does keto change BMR?: Short-term shifts exist; long-term weight change still ties to average intake vs expenditure.
Is this medical advice?: No—educational overview only; clinicians guide clinical nutrition.
Where is it implemented here?: The homepage calculator uses Mifflin–St Jeor internally for BMR.

Try the free calculator

Estimate maintenance calories, deficits, surpluses, and macro targets in one place—updated live as you adjust your inputs.

Open calorie calculator

Presets: fat loss, keto macros, men, women.