HealthApril 12, 2026

Mifflin-St Jeor vs Harris-Benedict: Which Calorie Formula Is More Accurate?

Q: Which is more accurate: Mifflin-St Jeor or Harris-Benedict?

Mifflin-St Jeor is more accurate for most people. A 2005 study in the Journal of the American Dietetic Association found it predicted BMR within 10% of measured values for 82% of individuals, compared to 74% for Harris-Benedict. The American Dietetic Association recommends Mifflin-St Jeor as the best equation for estimating BMR in healthy adults.

Q: What is the Mifflin-St Jeor equation?

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161. Published in 1990, it was designed using data from modern populations and accounts for changes in body composition and lifestyle since the original Harris-Benedict equation was created in 1918.

Q: What is the Harris-Benedict equation?

The original 1918 Harris-Benedict equation: Men BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.755 × age). Women BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age). A revised version was published in 1984 by Roza and Shizgal. It tends to overestimate BMR by 5-15% compared to modern measurements.

Q: Why does Harris-Benedict overestimate calories?

Harris-Benedict was created in 1918 using data from young, active, lean individuals. Modern populations tend to have higher body fat percentages and more sedentary lifestyles, both of which lower BMR. The equation wasn't designed for today's bodies and consistently overestimates caloric needs, which can lead to unintended weight gain if used for calorie planning.

Q: Should I use BMR or TDEE for calorie counting?

Use TDEE (Total Daily Energy Expenditure), not BMR. BMR is just the calories your body burns at complete rest — lying in bed all day. TDEE multiplies BMR by an activity factor (1.2 for sedentary up to 1.9 for very active) to estimate total daily needs including exercise and daily movement. Eating at BMR would leave most people in a large caloric deficit.

By The hakaru Team·Last updated March 2026

Quick Answer

*Mifflin-St Jeor (1990) — more accurate for modern populations. Recommended by the American Dietetic Association. Accurate within 10% for 82% of people.
*Harris-Benedict (1918) — the original BMR formula. Tends to overestimate by 5-15% because it was developed with leaner, more active subjects.
*Use Mifflin-St Jeor. It’s the better formula for calculating your calories in 2026.

Feature	Mifflin-St Jeor	Harris-Benedict
Year Created	1990	1918 (revised 1984)
Accuracy	Within 10% for 82% of people	Within 10% for 74% of people
Tendency	Slight underestimate	Overestimates by 5-15%
ADA Recommended	Yes	No (outdated data)
BMR (30M, 180cm, 80kg)	1,780 cal	1,843 cal

TDEE Calculator →

What Is the Mifflin-St Jeor Equation?

Published in 1990 by Mifflin, St Jeor, and colleagues, this equation was developed using a diverse sample of modern adults — both normal weight and obese. It accounts for the body composition and activity patterns of contemporary populations.

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

For a 30-year-old man, 180 cm (5’11”), 80 kg (176 lbs): BMR = 800 + 1,125 − 150 + 5 = 1,780 calories/day.

What Is the Harris-Benedict Equation?

Created in 1918 by James Arthur Harris and Francis Gano Benedict, this was the first widely used BMR equation. It was revolutionary for its time but used data from mostly young, lean, active subjects at the Carnegie Nutrition Laboratory.

Men: BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) − (6.755 × age)

Women: BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) − (4.676 × age)

Same 30-year-old man: BMR = 66.5 + 1,100 + 900.5 − 202.7 = 1,864 calories/day. That’s 84 calories/day higher than Mifflin-St Jeor — about 5% more.

Key Differences

Accuracy in Modern Populations

A landmark 2005 study in the Journal of the American Dietetic Association compared both equations against indirect calorimetry (the gold standard for measuring BMR). Mifflin-St Jeor predicted BMR within 10% of actual measurements for 82% of participants. Harris-Benedict hit that mark for only 74%. The ADA subsequently recommended Mifflin-St Jeor as the preferred equation.

The Overestimation Problem

Harris-Benedict consistently overestimates by 5-15%. If you’re using it to set a calorie target, you’re eating 100-250 calories/day too many. Over a month, that’s 3,000-7,500 extra calories — roughly 1-2 pounds of potential fat gain. For someone trying to lose weight, this overestimation can stall progress entirely.

Who They Were Designed For

Harris-Benedict’s subjects were predominantly young, active, and lean. The average American in 2026 is heavier, less active, and carries more body fat than a 1918 lab volunteer. Mifflin-St Jeor was calibrated on subjects that look like us: a mix of weights, activity levels, and body compositions.

When to Use Mifflin-St Jeor

Calorie counting for weight loss. The slightly more conservative estimate prevents accidentally eating at maintenance.
General fitness planning. For most adults, it’s the most reliable starting point.
You’re overweight or obese. Mifflin-St Jeor handles higher body weights better than Harris-Benedict.
When accuracy matters. If you’re dialing in macros precisely, start with the better equation.

When Harris-Benedict Might Still Work

You’re young, lean, and very active. Harris-Benedict’s study population matches your profile more closely.
Using the 1984 revised version. Roza and Shizgal’s update is closer to Mifflin-St Jeor in accuracy.
Quick ballpark estimate. Both formulas get you in the right range. The difference is 50-100 calories for most people.

Which Is Better? Mifflin-St Jeor by a Clear Margin

The data is unambiguous. Mifflin-St Jeor is more accurate for more people. It’s the equation recommended by the American Dietetic Association and used by most modern TDEE calculators. Harris-Benedict isn’t wildly wrong — it’s just consistently a bit high, which can undermine weight loss goals.

That said, any formula is just a starting point. Monitor your weight and adjust calories based on real-world results every 2-3 weeks. No equation perfectly predicts your individual metabolism.

Calculate your TDEE with the Mifflin-St Jeor equation

Use our free TDEE Calculator →

Disclaimer: This guide is for educational purposes only and does not constitute medical or nutritional advice. Calorie formulas are estimates. Consult a registered dietitian for personalized nutrition planning.

Frequently Asked Questions

Which is more accurate: Mifflin-St Jeor or Harris-Benedict?

Mifflin-St Jeor. It predicts BMR within 10% for 82% of people vs 74% for Harris-Benedict. The American Dietetic Association recommends it as the best equation for healthy adults.

What is the Mifflin-St Jeor equation?

Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5. Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161. Published in 1990 using modern population data.

What is the Harris-Benedict equation?

Created in 1918: Men = 66.5 + (13.75 × kg) + (5.003 × cm) − (6.755 × age). It tends to overestimate BMR by 5-15% because it was calibrated on leaner, more active subjects.

Why does Harris-Benedict overestimate calories?

Its data came from 1918 subjects who were younger, leaner, and more active than today’s population. Modern bodies with higher fat percentages and less activity have lower BMRs than the equation predicts.

Should I use BMR or TDEE for calorie counting?

TDEE. BMR is only the calories burned at complete rest. TDEE adds your activity level. Eating at BMR would put most people in a large, unsustainable deficit.