Free estimated energy requirement calculator
See exactly how many calories you need each day. Enter your age, weight, height, sex, and activity level and the calculator returns your Estimated Energy Requirement from the Institute of Medicine's 2005 equation — the calories that maintain your weight, at every activity level — updated live, as you type.
On this page15 sections
| Activity | PA | Calories / day |
|---|---|---|
| Sedentary · daily living only | 1.00 | 2,514 cal/day |
| Low active · ~30–60 min/day | 1.11 | 2,749 cal/day |
| Active · ~60 min/day | 1.25 | 3,048 cal/day |
| Very active · heavy daily exercise | 1.48 | 3,540 cal/day |
EER is an estimate for healthy adults; individual needs vary. How accurate is this?
Results are estimates. Consult a professional.
How the EER calculator works
Your Estimated Energy Requirement (EER) is the number of calories you need each day to keep your body weight steady — the energy you burn through everything from breathing and digestion to walking, working, and exercise. The calculator takes five inputs: your sex, age, weight, height, and physical-activity level. It feeds them into the Institute of Medicine's EER equation, which was fitted directly to total-energy-expenditure measurements, and returns your maintenance calories per day.
What the number means
EER is a maintenance figure: eat that many calories and, on average, your weight holds. It already includes the calories you burn moving around — that is what the physical-activity coefficient does — so unlike a basal-metabolic-rate figure, you do not multiply it by anything afterwards. To lose weight you eat below your EER; to gain, above it. It is an estimate built from population averages, so treat it as a well-grounded starting point rather than a precise personal measurement.
What is the Estimated Energy Requirement (EER)?
The Estimated Energy Requirement (EER) is the average daily calorie intake predicted to maintain energy balance — and therefore body weight — in a healthy adult of a given age, sex, weight, height, and activity level. It was defined by the Institute of Medicine (IOM) in its 2005 Dietary Reference Intakes report, the same framework that sets official US and Canadian nutrient recommendations. EER is the reference value dietitians and food labels lean on when they talk about how many calories a person "needs" in a day.
What makes EER distinctive is how it was built. Rather than estimating resting metabolism and then guessing an activity multiplier, the IOM equations were regressed directly against total daily energy expenditure measured by the doubly-labelled water method — the gold standard for measuring how many calories people actually burn over days of normal life. That means the EER equation captures resting metabolism, the energy cost of activity, and the thermic effect of food all in one step.
EER vs TDEE vs BMR: what's the difference?
EER, TDEE, and BMR all answer questions about your calories, but they are not the same thing — and the difference is mostly about how the number is derived, not just what it represents.
| Metric | What it is | How it's calculated |
|---|---|---|
| BMR | Calories burned at complete rest | A formula (e.g. Mifflin-St Jeor) from weight, height, age, sex |
| TDEE | Total daily calories burned, all activity included | BMR × an activity factor (1.2 to 1.9) |
| EER | Calories needed to maintain weight (≈ total expenditure) | One IOM regression fitted to measured total expenditure |
EER and TDEE both estimate total daily calories; BMR is the resting floor underneath them.
So EER and TDEE estimate the same real-world quantity — the calories you burn in a full day — and for most adults they land within 5–10% of each other. The difference is the route. TDEE multiplies a separate BMR by a generic activity multiplier; the EER equation skips the BMR step and predicts total expenditure in one shot from data. BMR is different in kind: it is your resting burn only, the floor you would never multiply your intake by. If you want the BMR-times-factor approach, use the TDEE calculator; if you want the IOM reference value, this EER page is it.
The IOM / DRI equation behind EER
The calculator uses the IOM 2005 EER equations for normal-weight adults aged 19 and older. There is a separate equation for men and women, reflecting the average difference in body composition:
Read the structure carefully, because it differs from the BMR formulas. The equation starts from a sex-specific constant, subtracts an age term (energy needs fall slowly with age), and then adds a bracket combining weight and height that is multiplied by the PA coefficient. Only that bracket is scaled by activity — the constant and the age term are not. This is why EER cannot be reduced to a single "× activity factor" multiplier the way TDEE can.
The physical-activity (PA) coefficient explained
The PA coefficient is how the EER equation accounts for movement. It is not the same as the 1.2–1.9 activity factors used with BMR — the PA values are smaller because they multiply only part of the equation. The IOM defines four levels, and the coefficient differs by sex:
| Activity level | Men (PA) | Women (PA) | Typical week |
|---|---|---|---|
| Sedentary | 1.00 | 1.00 | Daily living only, no deliberate exercise |
| Low active | 1.11 | 1.12 | ~30–60 min/day of moderate activity |
| Active | 1.25 | 1.27 | ~60 min/day moderate, or equivalent |
| Very active | 1.48 | 1.45 | Heavy daily exercise or a physical job |
IOM 2005 physical-activity coefficients by sex. Pick the level that matches a typical week — most people overestimate.
Choosing the right level is the single biggest driver of your result: moving from sedentary to very active can swing the EER by 500 calories or more. The IOM defines these levels in terms of physical-activity level (PAL) — total expenditure divided by basal expenditure — but in everyday terms, "sedentary" means you do little beyond daily living, while "active" already implies a real daily exercise habit. When in doubt, pick the lower level.
A worked example using the EER calculator
Daniel is 30, stands 175 cm (1.75 m), weighs 75 kg, and trains most days, so he picks Active (PA = 1.25). Here is the arithmetic the calculator runs through the men's IOM equation, step by step.
Step 1 — The constant and the age term
The men's equation starts at 662 and subtracts the age term: 9.53 × 30 = 285.9. So far: 662 − 285.9 = 376.1.
Step 2 — The weight and height bracket
15.91 × 75 = 1,193.25, and 539.6 × 1.75 = 944.30. Added together the bracket is 2,137.55.
Step 3 — Apply the PA coefficient
Multiply the bracket — and only the bracket — by Daniel's PA of 1.25: 1.25 × 2,137.55 = 2,671.94.
Step 4 — Add it all up
How to use your EER for weight goals
Your EER is the maintenance line. Setting a calorie target from it is simple arithmetic: a pound of body fat is roughly 3,500 calories, so a 500-calorie daily deficit loses about a pound a week — a sustainable, widely used target.
- To maintain weight — eat at your EER. That is the figure the calculator returns at your activity level.
- To lose weight — subtract 250–500 calories a day for steady fat loss of about half a pound to a pound a week.
- To gain weight or muscle — add 250–500 calories a day for a lean, controlled gain.
Then check it against reality. The equation is built from population averages, so let your scale over two to three weeks be the real test — if your weight is not moving the way the numbers predict, adjust intake by 100–200 calories rather than assuming the formula is exact. To plan the deficit and macros, pair this with the calorie calculator and the calorie deficit calculator.
How accurate is the EER equation?
The EER equations are among the best-validated calorie predictions available, precisely because they were fitted to doubly-labelled water data rather than to resting-metabolism measurements. For most healthy, normal-weight adults the IOM equation predicts daily needs within roughly ±200–300 calories when the activity level is chosen honestly.
- Activity level dominates the error. The biggest source of inaccuracy is overstating how active you are — be conservative when choosing your PA level.
- Body composition isn't an input. Two people of the same weight and height get the same EER even if one carries far more muscle, which burns more at rest. EER captures averages, not your individual lean mass.
- Designed for healthy adults. The equations assume a normal-weight, healthy adult; they are less reliable at the extremes of body size and don't account for illness, medication, or pregnancy.
Limitations and when EER doesn't apply
EER is a planning estimate, not a diagnosis or a prescription. Use it to set a sensible starting calorie target, and read these limits before you treat the number as exact:
- Adults only. This calculator uses the adult (19+) equations. Children and teenagers have age-banded EER equations with a growth allowance.
- Not for pregnancy or breastfeeding. Those states add hundreds of calories through separate IOM equations not modelled here.
- Averages, not individuals. Genetics, thyroid function, and lean-mass differences mean your true needs can sit above or below the estimate.
- Maintenance, not a deficit target. EER tells you what holds your weight steady; you choose the deficit or surplus from there.
Formula and sources
This calculator uses the Estimated Energy Requirement (EER) equations from the Institute of Medicine's 2005 Dietary Reference Intakes for adults aged 19 and over, with the IOM physical-activity coefficients (1.00 sedentary to 1.48/1.45 very active). The equations were derived from total-energy-expenditure measurements by the doubly-labelled water method.
Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005).Frequently asked questions about the free estimated energy requirement calculator
About this EER calculator
This Estimated Energy Requirement calculator runs entirely in your browser. Your age, weight, height, sex, and activity level never leave your device — nothing is sent to a server, logged, or shared. It uses the Institute of Medicine's 2005 DRI EER equations for adults (19+) and their physical-activity coefficients, updating instantly as you type.
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