Mifflin-St Jeor vs Harris-Benedict: Which BMR Formula Is Better?

Every calorie calculator starts with BMR — Basal Metabolic Rate. The two names you see everywhere are Mifflin-St Jeor and Harris-Benedict. They often differ by 50–150 kcal/day, which adds up over a month.

So which one should you use?

Mifflin-St Jeor (1990) — the modern default

Developed from a larger, more diverse sample. Most nutrition apps and research summaries treat it as the best general-purpose BMR estimate for healthy adults.

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

Use when: You are a typical adult without a reliable body fat measurement. This is our calculator default.

Revised Harris-Benedict (1984)

A revision of the 1919 classic. Still common in older tools and clinical settings.

Men: BMR = 88.362 + 13.397×W + 4.799×H − 5.677×A
Women: BMR = 447.593 + 9.247×W + 3.098×H − 4.330×A

(W = kg, H = cm, A = years)

Use when: You want to compare against legacy calculators, or your dietitian references this formula.

Katch-McArdle — for known lean mass

BMR = 370 + 21.6 × lean body mass (kg)

Requires accurate body fat % (DEXA, skilled caliper reading). Guessing body fat can make this less accurate than Mifflin-St Jeor.

Use when: You have a real body composition measurement, not a bathroom-scale guess.

Side-by-side: what changes in practice?

For a 28-year-old man, 80 kg, 178 cm:

Formula	Approx. BMR
Mifflin-St Jeor	~1,780 kcal
Harris-Benedict (revised)	~1,855 kcal
Difference	~77 kcal/day

At moderate activity (×1.55), that is a ~119 kcal difference in TDEE — about 0.25 lb (0.1 kg) per week in fat loss projections.

Takeaway: Formula choice matters, but consistency and adherence matter more. Pick one, track results, adjust.

What research generally says

Validation studies (various populations) tend to favor Mifflin-St Jeor for predicting resting energy expenditure in non-obese and obese adults. Harris-Benedict can overestimate in some modern sedentary groups.

No formula is perfect for every individual — thyroid health, muscle mass, genetics, and sleep all shift real burn.

How to test which works for YOU

1. Calculate TDEE with Mifflin-St Jeor in our calculator
2. Eat at maintenance ±100 kcal for 14 days
3. Track morning weight trend
4. If weight creeps up → TDEE estimate may be high; if down → may be low
5. Adjust calories by 100–150, not 500

Try all three in one place

Calorie Cal supports Mifflin-St Jeor, Revised Harris-Benedict, and Katch-McArdle (with optional body fat %). Switch formulas and watch BMR, TDEE, and goal calories update instantly.

Read next: What is TDEE? · How to calculate macros