BMR Calculator (Mifflin-St Jeor)
Estimate basal metabolic rate with Mifflin-St Jeor: 10 x kg + 6.25 x cm - 5 x age, plus 5 for men or minus 161 for women. Result in kcal/day.
BMR (kcal/day)
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Mifflin-St Jeor: the modern BMR standard
Published in 1990, the Mifflin-St Jeor equation estimates Basal Metabolic Rate (BMR), which is the energy your body burns at complete rest. For men it's BMR = 10·kg + 6.25·cm − 5·age + 5; for women, BMR = 10·kg + 6.25·cm − 5·age − 161. Mifflin and colleagues arrived at it by re-running the older Harris-Benedict (1919) data against a modern population, which cut down the systematic overestimation. Expect an error of around ±200 kcal/day. The ACSM now points to it as the reference equation for healthy adults. A quick example — a 70 kg, 175 cm, 30-year-old man works out to 10·70 + 6.25·175 − 5·30 + 5 = 1,700 kcal/day.
Applications and context
Whether the work is clinical nutrition, body recomposition, diabetes management or planning calories around sport, Mifflin-St Jeor is usually where people start. Once you have BMR, multiply it by an activity factor — 1.2 for sedentary up to 1.9 for very active — to get your TDEE. From there you adjust calories for whatever you're after, be it losing fat, gaining lean mass or holding steady.
FAQ
Why is Mifflin-St Jeor preferred over Harris-Benedict? The 1919 dataset rested on a handful of subjects whose body composition doesn't match people today. Mifflin's sample of 498 subjects came back with lower mean errors, and it's what the ACSM references now.
How accurate is it? It lands within ±10% for roughly 80% of healthy adults. Accuracy slips at the extremes of body composition, whether that's very obese or very lean, so reach for Katch-McArdle if you know your body-fat %.
Does it work for children? No. For anyone under 18, turn to the Schofield or FAO/WHO equations. Mifflin-St Jeor was validated on adults aged 19–78.
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Ship Roll Period (IMO IS Code)
Computes the natural roll period of a ship using the empirical formula of the IMO International Code on Intact Stability (IS Code 2008), used in the weather criterion and in the inclining experiment. The period is T = 2 × C × beam ÷ square root of GM, with the coefficient C = 0.373 + 0.023 × (beam ÷ draught) − 0.043 × (length ÷ 100), so that rolling gets faster as the metacentric height grows. The number indicates comfort and safety: short periods, below some 8 seconds, reveal a stiff ship that rolls with high acceleration and punishes cargo and crew; long periods indicate a tender ship, with little stability reserve. The IMO empirical form was adopted rather than the pendulum expression T = 2π × radius of gyration ÷ square root of (g × GM), because the roll radius of gyration is rarely known on board — which is exactly what the coefficient C estimates from hull geometry. Enter the beam, the draught, the waterline length and the metacentric height GM.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.