Fitness · 5 min read
How to Calculate BMR
Mifflin–St Jeor calories at rest — and what the number is not
Basal metabolic rate (BMR) estimates the calories your body uses at rest. This tutorial walks through the Mifflin–St Jeor formulas, a 70 kg / 175 cm / age 30 worked example, and a playground that substitutes your numbers. BMR is an estimate of resting energy, not a meal plan or a medical assessment.
Written by the My Calculator Stack editorial team. About our methods
BMR is an estimate of resting energy, not a diet prescription or medical advice. It does not replace a clinician or a registered dietitian.
1.What BMR is
BMR is an estimate of calories burned at complete rest — the energy needed to keep breathing, circulating blood, and maintaining temperature. It is not a daily meal plan, a weight-loss target, or medical advice. Activity, thermic effect of food, and exercise sit on top of BMR (often as TDEE). Treat the number as a resting-energy screen, then talk to a qualified clinician if you need a diet or a care plan.
2.The formula
This site uses Mifflin–St Jeor (1990), not Harris–Benedict. Weight w is in kilograms, height h in centimeters, and age a in years. Male: 10w + 6.25h − 5a + 5. Female: 10w + 6.25h − 5a − 161. US customary inputs convert first: pounds × 0.45359237 → kg, and inches × 2.54 → cm. After that conversion the same formulas apply, so Metric and US results stay comparable.
\[ \begin{aligned}\mathrm{BMR}_{\mathrm{male}} &= 10w + 6.25h - 5a + 5 \\\mathrm{BMR}_{\mathrm{female}} &= 10w + 6.25h - 5a - 161\end{aligned} \]
3.Worked example
Take a metric male, 70 kg, 175 cm, age 30 — the same defaults as the BMR calculator. Then 10×70 + 6.25×175 − 5×30 + 5 = 700 + 1093.75 − 150 + 5 = 1648.75 kcal/day. The female formula with those same size and age inputs replaces +5 with −161 and gives 1482.75 kcal/day. In US units that size is about 154 lb and 69 in; convert to kilograms and centimeters and you get the same BMR.
\[ BMR=10(70)+6.25(175)-5(30)+5=1648.75 \]
4.Resting energy playground
Switch Metric/US and male/female, then move weight, height, and age to see BMR update and the energy bar fill. The caption substitutes Mifflin–St Jeor with your current numbers. This is a teaching widget — no favorites, no full calculator chrome. Open the BMR calculator when you want the standalone tool.
Inline playground
BMR
1648.75 kcal/day
10×70 + 6.25×175 − 5×30 + 5 = 1648.75
Screening aid only — BMR is an estimate of resting energy, not a diet prescription or medical advice.
Open the full BMR calculator →5.Open the full calculator
The BMR calculator uses the same Mifflin–St Jeor equation, the same 70 kg / 175 cm / age 30 example, and the same screening disclaimer, with How it works, FAQ, and related fitness tools on one page. Browse other fitness calculators if you need BMI, calories, or body-fat estimates next.
Try it yourself
Open the related calculator and put these formulas to work.