EER Calculator
Estimate your daily caloric needs using the official Institute of Medicine equations — covering every life stage from infancy through lactation
Enter age in years. For infants under 1 year, enter 0 and use the months field.
Standing height — used in the IOM height term of the EER equation
Body weight — used directly in the IOM weight term of the EER equation
Calculate Your Energy Requirement
Enter your age, sex, weight, height, and physical activity level, then click Calculate EER to see your results.
How to Use the EER Calculator
Frequently Asked Questions
What is EER and how does it differ from TDEE or BMR?
EER (Estimated Energy Requirement) is the average daily dietary energy intake predicted to maintain energy balance in a healthy person at their current weight and activity level. It is defined by the Institute of Medicine in the Dietary Reference Intakes (DRI) framework. TDEE (Total Daily Energy Expenditure) is conceptually similar but is typically estimated by multiplying BMR (Basal Metabolic Rate) by an activity factor. The critical difference is the methodology: EER uses empirically derived polynomial regression equations from doubly labeled water (DLW) studies — the gold standard method for measuring energy expenditure in free-living people. BMR-multiplier approaches use theoretical approximations. EER equations also differ by life stage, with separate equations for infants, children, adolescents, and adults, whereas most TDEE calculators apply a single adult equation to everyone. For clinical and research use, EER from IOM equations is the scientifically preferred method.
What are the four physical activity levels and how do I choose mine?
The IOM defines four Physical Activity Level (PAL) categories based on observed PAL values from doubly labeled water studies. Sedentary (PAL 1.0–1.39) means only typical daily life activities — sitting at a desk, cooking, slow walking — with no deliberate exercise. This is equivalent to zero additional miles walked per day beyond normal movement. Low Active (PAL 1.4–1.59) adds 30–60 minutes of moderate-intensity activity such as brisk walking, leisurely cycling, or light household work — roughly equivalent to an extra 2.2 miles walked per day. Active (PAL 1.6–1.89) requires at least 60 minutes of moderate physical activity daily — equivalent to about 7.3 extra miles. Very Active (PAL 1.9–2.5) combines at least 60 minutes of moderate and 60 minutes of vigorous activity daily — equivalent to 16.7 extra miles. Most office workers fall in the Sedentary to Low Active range. If you exercise 3–5 days per week for an hour, you are likely Active. Very Active applies to athletes in daily training or people with extremely demanding physical jobs.
How does EER change during pregnancy?
The IOM pregnancy energy adjustments are added on top of the woman's base EER computed from her current weight, height, age, and activity level. In the first trimester, the adjustment is zero additional calories — the evidence base shows most women have sufficient energy reserves early in pregnancy, and some naturally reduce activity. In the second trimester, an additional 340 kcal/day is needed to support increasing fetal growth, placental development, and maternal tissue expansion. By the third trimester, the addition rises to 452 kcal/day to meet the accelerating energy demands of the final growth phase. These adjustments assume a woman is gaining pregnancy weight within the IOM-recommended range. Women carrying multiples or those with gestational complications may have different needs. Always work with a healthcare provider or registered dietitian for personalized pregnancy nutrition guidance.
Why are there different equations for children, adolescents, and adults?
The IOM uses age-specific EER equations because the relationship between body size, activity, and energy expenditure changes dramatically across the lifespan. Infant equations use body weight only because PA assessment is impractical at this stage, and energy needs are dominated by rapid growth — the age-specific constants (175, 56, 22, and 20 kcal/day for successive infant age groups) represent energy deposited for growth tissue at each stage. Children aged 3–8 and adolescents 9–18 use equations with a +20 or +25 kcal/day growth energy deposit baked in, plus sex-specific PA coefficient sets that differ from adult values. Adult equations have an aging term (negative coefficient on age) that captures the decline in total energy expenditure as lean body mass decreases with age. Using an adult equation for a child would yield inaccurate results, which is why the IOM provides separate validated equations for each group.
What does doubly labeled water mean and why does it matter for EER?
The doubly labeled water (DLW) method is the gold standard for measuring total daily energy expenditure in free-living people — meaning people going about their normal lives, not confined to a lab. Participants drink water where the hydrogen and oxygen atoms have been replaced with stable (non-radioactive) isotopes: deuterium (²H) and oxygen-18 (¹⁸O). The body uses these isotopes normally, and they are eliminated at slightly different rates. The difference between the elimination rates reflects the rate of carbon dioxide production, which can be precisely converted to energy expenditure using known respiratory quotient relationships. DLW is accurate to within about 2–3% and requires no behavioral changes from the participant. The IOM EER equations were derived by regressing DLW-measured total energy expenditure against age, sex, weight, height, and physical activity level in thousands of study participants across all age groups. This means EER equations are grounded in actual measured energy expenditure, not theoretical metabolic formulas.
Should I eat exactly my EER value, or adjust it?
EER is designed to maintain current body weight and energy balance — it is a maintenance target, not a universal prescription. Whether your EER is the right calorie level depends on your goals and current health status. If you want to maintain your weight, eating close to your EER is appropriate. If you want to lose body fat, a deficit of 300–500 kcal/day below your EER is a common evidence-based starting point, aiming for roughly 0.5–1 pound of fat loss per week. If you are trying to gain muscle or recover from illness or surgery, eating above your EER provides the surplus needed. EER also assumes you are at a healthy weight — if you are significantly above or below a healthy weight, your actual energy needs may differ from the prediction, since EER equations are population-level estimates. For the most personalized guidance, consult a registered dietitian who can account for your individual metabolic history, body composition, medical conditions, and dietary preferences.