π₯ Estimated Energy Requirement Calculator
The Institute of Medicine equations for daily calorie needs.
For informational purposes only, not medical advice. Consult a healthcare professional.
Your Estimated Energy Requirement is the daily calories that keep your weight stable, and the Institute of Medicine equations put a 35-year-old active man at 80 kg and 180 cm at about 3,134 kcal per day. The same formulas give a 35-year-old low-active woman at 65 kg and 165 cm roughly 2,135 kcal. Enter your numbers for your EER plus sensible loss and gain targets.
How to Use This Calculator
EER comes from the Institute of Medicine's 2005 macronutrient report, built on doubly labeled water studies, which is the gold standard for measuring real-world calorie burn. It covers adults 19 and older.
Enter age, sex, weight in kilograms, and height in centimeters. The equations use metric units throughout.
Pick the activity level honestly. Sedentary means a desk day with little intentional exercise; low active is 30 to 60 minutes of moderate activity daily; active is 60+ minutes; very active is hard training or a physical job plus training.
Read your EER, then the minus-500 and plus-300 rows for gradual fat loss (about a pound a week) or lean gain. Those adjustments assume the EER itself is right, so track weight for two weeks before trusting them blindly.
The IOM Equations
Age subtracts calories every year because metabolic rate drifts down with age and muscle loss. Weight adds calories because bigger bodies cost more to run and move. Height adds calories for similar reasons. The physical activity coefficient multiplies the weight-and-height term, which is why activity level swings the result more than any other input: going from sedentary to very active multiplies that whole term by nearly 1.5. These are maintenance equations. They do not include pregnancy, lactation, or the extra cost of gaining muscle, each of which adds its own allowance in the full IOM report.
Worked Example
Man, 35 years, 80 kg, 1.80 m, active (PA 1.25): 662 - 9.53(35) + 1.25(15.91(80) + 539.6(1.80)) = 662 - 333.55 + 1.25(1272.8 + 971.28) = 328.45 + 2805.10 = 3133.55, about 3,134 kcal/day. Drop him to sedentary (PA 1.0): 328.45 + 2244.08 = 2573 kcal, a 561 kcal swing from activity alone. Woman, 35, 65 kg, 1.65 m, low active (PA 1.12): 354 - 241.85 + 1.12(608.4 + 1197.9) = 112.15 + 2023.06 = 2135 kcal/day. I checked both against the equations directly, and the calculator reproduces them exactly.
EER vs BMR vs TDEE
| Term | What it is | Typical size |
|---|---|---|
| BMR | Calories burned at complete rest | 60-70% of EER |
| EER | Total daily need at your activity level | The maintenance number |
| TDEE | Same idea as EER, different formula family | Usually within 5-10% of EER |
People use EER and TDEE interchangeably in conversation, and for practical purposes they are the same concept: everything you burn in a day. BMR is just the sleeping-under-a-blanket portion. If you have tracked food and weight before and your real maintenance differs from the EER by more than 10%, trust your own data; equations describe populations, and individuals vary with muscle mass, NEAT (fidgeting and daily movement), and genetics. For the other half of the energy equation, our BMR calculator isolates the resting portion, our macro calculator splits the calories into protein, carbs, and fat, and our weight loss timeline turns a deficit into a calendar.
Where EER Gets Misused
The most common misuse is treating the number as a prescription rather than a starting estimate. Two weeks of consistent tracking beats any equation: if weight is flat at 2,600 kcal, maintenance is 2,600 regardless of what the formula said. Athletes in heavy training, people with very high muscle mass, and anyone with a thyroid disorder or on weight-affecting medication will deviate systematically. The equations also assume weight stability; during active weight loss, metabolic adaptation shaves 5 to 15% off predicted expenditure over months, which is why plateaus happen at intakes that "should" still be a deficit. Recalculate every 5 kg of weight change, and treat the loss and gain rows as starting points to adjust, not promises.
Putting the Number to Work
A maintenance number only helps if eating matches it within a couple hundred calories, and humans are bad at estimating portions. A food scale for two weeks calibrates your eye permanently; most people discover their "tablespoon" of peanut butter is two. Protein around 1.6 to 2.2 g per kg protects muscle in a deficit, fiber (see our fiber targets) controls hunger, and sleep under 7 hours measurably increases next-day intake. None of that changes the EER, but it changes whether you can live inside it.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is EER in nutrition?
Estimated Energy Requirement: the average daily calories predicted to maintain energy balance in a healthy adult of a given age, sex, weight, height, and activity level. It comes from the Institute of Medicine's 2005 Dietary Reference Intakes report.
How is EER different from TDEE?
Conceptually they are the same thing: total daily energy expenditure. EER is the IOM's equation set; TDEE usually refers to the Mifflin-St Jeor or Harris-Benedict based estimates. They typically land within 5-10% of each other.
What are the physical activity coefficients?
For men: sedentary 1.00, low active 1.11, active 1.25, very active 1.48. For women: 1.00, 1.12, 1.27, 1.45. They multiply the weight-and-height term, so activity level moves the result more than any other input.
How many calories should I eat to lose weight?
A common starting point is EER minus 500 kcal per day, which predicts about a pound (0.45 kg) of fat loss per week. Track for two weeks and adjust: if loss is slower than expected, the EER estimate was high for you.
Does EER work for teenagers?
Not directly; the IOM published separate equations for ages 3-18 that add growth costs. This calculator is for 19 and up. Teen athletes and growing adolescents need the pediatric equations or a dietitian.
Why does EER decrease with age?
Resting metabolic rate falls with age, mostly because muscle mass declines (sarcopenia) and activity often drops. The equations subtract about 7-10 kcal per year of age, which compounds to several hundred calories between 30 and 70.
Is the IOM equation accurate?
It was built on doubly labeled water data, the best available method, and performs well at the population level. Individuals vary by roughly plus or minus 10-15%, mostly from muscle mass and daily movement differences the equation cannot see.
Should athletes use EER?
As a starting point, yes, at the very-active level. Endurance athletes in peak training may exceed even that and do better with sport-specific formulas or measured expenditure. Strength athletes should recalculate as muscle mass changes.
Does EER include exercise calories?
Yes, through the activity coefficient. Do not add workout calories on top of an active-level EER; that double counts. Pick the activity level that already describes your training, then eat to the number.
How often should I recalculate EER?
After every 5 kg of weight change, when your training volume changes substantially, or yearly as you age. During long diets, recalculate monthly since metabolic adaptation lowers expenditure as you get lighter.