Compare two resting-metabolism formulas

You enter weight, height, age, and formula sex. The tool computes Mifflin-St Jeor, featured because it is the resting equation then reused for TDEE and calories on HexaCalc. It also computes Harris-Benedict as re-evaluated by Roza and Shizgal in 1984, so the gap between two published models is visible rather than hidden. Neither is calorimetry. In the lab, strict BMR and resting energy expenditure (REE) are not the same; in public tools, “BMR” often means this resting prediction.

Mifflin femme : 10w + 6,25h − 5a − 161    |    homme : 10w + 6,25h − 5a + 5

Harris-Benedict 1984 femme : 447,593 + 9,247w + 3,098h − 4,330a

Harris-Benedict 1984 homme : 88,362 + 13,397w + 4,799h − 5,677a

Mifflin-St Jeor was proposed as a new predictive equation in healthy adults. Harris-Benedict, older, was re-evaluated in 1984 on resting expenditure and body-cell mass. We do not claim one equation “wins” for every body: comparison studies exist, with results that depend on the group tested, and we do not invent their error percentages. Showing both avoids treating a single number as metabolic truth. To move to a full day, multiply Mifflin (not Harris) by a factor on the TDEE page — that is the tool’s internal consistency choice.

Weight

Both formulas are linear in weight, with different slopes (10 vs 9.247 or 13.397).

Height

Mifflin weights height more (6.25) than Harris-Benedict for women (3.098).

Age

Mifflin age coefficient: −5 per year. Harris-Benedict women: −4.33; men: −5.677.

Sex

Without it, neither publication can be applied as written.

Assumptions

• Adults; outside ICU or clinical calorimetry protocols.
• Typed weight and height are current measurements.
• The Mifflin result is what TDEE and calories reuse next.

Limits

• This is not BMR measured with an oxygen mask.
• Body composition is not in these equations.
• Illness, fever, hyper/hypothyroidism, sarcopenia: outside the model.
• The gap between the two formulas is not an “official scientific range”; it is simply two predictions.

If the two numbers are close, you will mostly see the activity rung’s effect once you go to TDEE. If they spread more, remember that predicted rest is already uncertain by a few percent, sometimes more, depending on the person. Neither 1,780 nor 1,854 kcal “explains” a weight stall. For the day, open TDEE from Mifflin.

• Multiplying Harris-Benedict by the TDEE page’s activity factor and comparing to our calories.

  On HexaCalc, TDEE and calories start from Mifflin. Mixing bases creates a fake gap.

• Picking the higher of the two “to eat more.”

  This is not a buffet of formulas. The primary is Mifflin; Harris-Benedict is for comparison.

• Concluding a metabolic disorder because the number “looks low.”

  Without a measurement and a clinic, a predicted BMR diagnoses nothing. Medical advice is a different channel.

• TDEE calculatorTDEE here is Mifflin-St Jeor resting metabolism times an activity factor. It includes no deficit, no surplus, and no 1,200 kcal floor.
• Calorie calculatorThree steps: Mifflin-St Jeor resting burn, times a lump activity factor, then a goal offset. The result is an estimate, not a diet.
• Macro calculatorThe tool applies an energy percent to the calories you type, then converts with 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat. These are templates, not a care plan.

Written by Rédaction HexaCalc (editorial team). Content last updated: August 25, 2026. No third-party medical or financial review is claimed.

• Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO — A new predictive equation for resting energy expenditure in healthy individuals (1990) — The American Journal of Clinical Nutrition
• Roza AM, Shizgal HM — The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass (1984) — The American Journal of Clinical Nutrition