Oxford Henry BMR calculator

Basal metabolic rate is the energy your body expends at complete rest to sustain vital processes such as breathing, circulation, cellular repair and thermal regulation. The Oxford equations, published by Henry in 2005, estimate that daily calorie floor from body weight, biological sex and a discrete age band, using a large multi-ethnic dataset that deliberately reduced over-representation of European military cohorts found in older Schofield tables.

What the Oxford Henry equations compute and why they matter

The Oxford (Henry 2005) equations estimate basal metabolic rate from body mass, sex and chronological age band. For each combination of sex and band the formula is a simple linear model: BMR in megajoules per day equals coefficient a times weight in kilograms plus coefficient b. Six age bands are defined for each sex—zero to three years, three to ten, ten to eighteen, eighteen to thirty, thirty to sixty, and sixty and over—with lower bounds inclusive and upper bounds exclusive except for the open sixty-plus group.

Those coefficients come from a re-analysis of more than ten thousand BMR measurements that excluded heavily over-represented Italian military subjects from earlier Schofield databases and added thousands of observations from tropical and developing regions. The result is a resting energy floor, not total daily energy expenditure: it does not add exercise, non-exercise activity thermogenesis, the thermic effect of food or illness-related demand.

UK SACN guidance and many European dietetic manuals prefer Henry over older FAO tables for contemporary multi-ethnic adults because predicted values tend to run lower and closer to measured resting expenditure in validation cohorts. Use the number as a baseline, then layer activity factors or measured intake when you need a full calorie budget.

How to read your Oxford Henry result

Send three required fields: weight as a positive number in kilograms, sex as male or female (short forms m, f, man and woman are accepted), and age as a non-negative number of years at most one hundred thirty. Age is mapped automatically to the Henry band: for example age thirty selects the thirty-to-sixty band, age twenty-five selects eighteen-to-thirty, and age sixty selects the open sixty-plus band. There is no network hop, model call or randomness, so latency stays in the pure edge-parse band.

Pair this result with your own physical activity level multiplier if you need estimated total energy expenditure; this capability deliberately stops at BMR so product copy and clinical tools stay honest about what was measured.

Where it fits in real health and product workflows

Nutrition coaching apps collect onboarding anthropometrics and need a defensible resting calorie number that aligns with UK and European dietetic guidance before suggesting macros. Clinical research coordinators batch-convert study-subject measurements into BMR for secondary analysis without spreading spreadsheet formulas that diverge by cell or use outdated Schofield constants. Fitness platforms show members a transparent Oxford Henry baseline next to wearable burn estimates so users understand the resting floor versus the daily total.

Insurance and employer wellness portals can pre-fill educational calculators without shipping proprietary engines or calling external nutrition APIs. The browser path is free for single checks: enter seventy kilograms, male, age thirty, and confirm the thirty-to-sixty male coefficients produce a stable kcal-per-day figure.