How this instrument works
Estimated Energy Requirement comes from the Institute of Medicine's 2005 Dietary Reference Intakes report, and it is a different design from a typical two-stage calorie estimate. Rather than compute a resting rate and multiply by an activity factor afterward, the IOM fit one full equation per sex, with age, weight, height, and a physical-activity (PA) coefficient combined directly inside a single line: 662 minus 9.53 times age, plus PA times the sum of 15.91 times weight and 539.6 times height, for men; 354 minus 6.91 times age, plus PA times the sum of 9.36 times weight and 726 times height, for women — weight in kilograms, height in metres.
That is a genuinely different design from this site's own TDEE calculator, which multiplies a Mifflin-St Jeor resting rate by a separate activity factor after the fact. Here, the PA coefficient sits inside the same equation as age, weight, and height, and the surrounding constants differ by sex outright — the women's line is not the men's line with a different multiplier snapped on, it is its own fitted equation.
One simplification is worth stating plainly: the IOM's own published tables assign slightly different PA coefficients to men and women within the same tier — 'active,' for example, sits nearer 1.25 for men and 1.27 for women in the source tables, not one shared number. This instrument uses a single PA value per tier for both sexes to keep the interface simple, which introduces a small drift, typically well under two percent, from the fully sex-specific IOM coefficients.
As with any predictive equation, EER describes what a group of similar people tends to require, not a guaranteed figure for one individual. Actual need shifts with muscle mass, health conditions, sleep, and genuine day-to-day movement in ways four or five inputs cannot capture; treat the output as a considered starting point for planning intake, adjusted against how your own weight moves over several weeks.
- Set Sex — Male or Female — which selects an entirely separate equation, not just a different constant.
- Enter Age in years, Weight in kilograms or pounds, and Height in your preferred unit.
- Choose a Physical activity level from Sedentary, Low active, Active, or Very active.
- Read Estimated Energy Requirement in kcal per day; the working shows each term of the sum.
Worked example — active man, 30, 70 kg, 1.75 m
Age term: 9.53 × 30 = 285.9, subtracted from 662, leaving 376.1. Inside the brackets: 15.91 × 70 = 1113.7 and 539.6 × 1.75 = 944.3, summing to 2058. Multiply by the Active coefficient of 1.26: 1.26 × 2058 = 2593.08. Add that to 376.1 for a total of 2969.18 kcal per day.
Switch to a sedentary 30-year-old woman, 60 kg at 1.65 m: 6.91 × 30 = 207.3, subtracted from 354 leaves 146.7; inside the brackets, 9.36 × 60 = 561.6 and 726 × 1.65 = 1197.9, summing to 1759.5; at a sedentary coefficient of 1.0 that stays 1759.5, giving a total of 1906.2 kcal per day. A very active 50-year-old man, 90 kg at 1.80 m, runs the men's equation instead: 662 minus 476.5 leaves 185.5, the bracket sums to 2403.18, and at a Very active coefficient of 1.465 that becomes roughly 3520.66, for a total of about 3706.16 kcal per day.
Questions
How is EER different from the TDEE calculator on this site?
TDEE here works in two stages — it computes a Mifflin-St Jeor resting rate, then multiplies that figure by a separate activity factor. EER instead uses the Institute of Medicine's 2005 equations, which build the physical-activity coefficient directly into one sex-specific formula alongside age, weight, and height, rather than layering it onto a separately computed resting number. The two approaches can return noticeably different figures for the same person, and neither is more official than the other — they come from different research traditions.
Why are there separate equations for men and women?
Because the Institute of Medicine fit its Dietary Reference Intakes equations from measured energy expenditure data collected separately by sex, and men and women showed different relationships between age, weight, height, and total energy use. Rather than force one line through both datasets, the 2005 report published two full equations, each with its own constants and its own physical-activity coefficient set.
Does this instrument use the exact IOM activity coefficients for both sexes?
Not quite, and it is worth saying plainly: the IOM's published tables assign slightly different PA numbers to men and women within the same tier — 'active,' for instance, sits nearer 1.25 for men and 1.27 for women rather than one shared figure. This calculator uses a single PA value per tier for both sexes to keep the interface simple, which introduces a small drift, typically well under two percent, from the fully sex-specific IOM coefficients.
What counts as 'active' versus 'very active' here?
The IOM's tiers describe roughly how much daily movement someone gets beyond a sedentary baseline: Active corresponds to living a moderately busy lifestyle without formal exercise on top, while Very active describes a substantial amount of daily activity, comparable to walking many extra miles a day. Pick the tier that matches a typical week, not an unusually hard or easy one.
Is EER a number I should eat exactly?
No — it is a population-based estimate of maintenance energy for someone of your description, not a personal measurement. Real requirements vary with muscle mass, health status, and how closely an actual week matches the activity tier selected. Use it as a starting figure, then adjust based on how weight trends over several weeks rather than treating it as exact.
Where does the EER equation come from?
From the Institute of Medicine's Food and Nutrition Board, in the 2005 report 'Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids,' published by the National Academies Press. It is the same body of work behind many national dietary reference values, built from doubly labelled water studies measuring free-living energy expenditure.
References
- Institute of Medicine 2005 — Dietary Reference Intakes for Energy (National Academies Press)
- CDC — Physical Activity Basics
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.