Your Estimated Energy Requirement (EER) is the number of calories a day that should keep your weight stable. It comes from equations in the National Academies' 2023 Dietary Reference Intakes for Energy, based on age, sex, height, weight and activity level. A 25-year-old reference man who is low active needs about 2,988 kcal/day.
The calculator covers adults, children aged 3–18, infants, pregnancy (2nd and 3rd trimester) and breastfeeding, using the NASEM (National Academies of Sciences, Engineering, and Medicine) equations exactly as published.
How to use the EER calculator
- Choose sex and enter age in years. For babies, enter fractions of a year (6 months = 0.5).
- Enter current weight and height in lb/in or kg/cm.
- Pick a physical activity level from the table below.
- If you are pregnant (2nd or 3rd trimester) or breastfeeding, choose that option. For pregnancy, add weeks of gestation and your BMI before pregnancy.
- Read your EER in kcal/day. The calculator also shows the value at the other activity levels.
Physical activity levels
| Level | Adult example (NASEM Table 7-1) | PAL, adults |
|---|---|---|
| Inactive | Only the activities of daily living | 1.0–1.53 |
| Low active | Daily living plus about 60–80 minutes of walking at 3–4 mph | 1.53–1.68 |
| Active | Daily living plus about 30–50 min walking, 45 min moderate cycling and 40 min doubles tennis | 1.68–1.85 |
| Very active | Daily living plus about 45 min moderate cycling, 25 min jogging (10 min/mile) and 60 min doubles tennis | 1.85–2.5 |
PAL (physical activity level) is total energy expenditure divided by basal energy expenditure. The ranges above are NASEM Table 5-4 for adults; children's ranges are slightly different.
How EER is calculated
Each equation has the form EER = intercept + a × age + b × height (cm) + c × weight (kg), with separate coefficients for each sex and activity level (NASEM 2023, Table S-3 for adults). For example, men 19+: inactive 753.07 − 10.83 × age + 6.50 × cm + 14.10 × kg. Women 19+: inactive 584.90 − 7.01 × age + 5.72 × cm + 11.71 × kg.
- Children 3–18 use their own equations (Table S-2) plus an energy cost of growth of 15–30 kcal/day depending on age and sex.
- Infants 0–2 have no activity levels; a growth allowance is added that is largest in the first months.
- Pregnancy, 2nd and 3rd trimester: a pregnancy equation that adds 9.16 kcal/day per week of gestation, plus energy deposition set by pre-pregnancy BMI (Table S-4).
- Breastfeeding: the non-pregnant equation plus 400 kcal/day (exclusive, 0–6 months) or 380 kcal/day (partial, 7–12 months).
Worked examples
Man, 40, 5′10″, 190 lb, low active
Converted: 177.8 cm and 86.2 kg. EER = 2,912 kcal/day. If he were inactive it would be 2,691 kcal, and active 3,102 kcal.
Woman, 30, 165 cm, 70 kg, inactive, 28 weeks pregnant
Not pregnant, her EER would be 2,138 kcal/day. At 28 weeks with a normal pre-pregnancy BMI, the pregnancy equation gives 2,433 kcal/day.
Woman, 30, 165 cm, 65 kg, inactive, exclusively breastfeeding
Her non-pregnant EER is 2,080 kcal/day. Adding 400 kcal for exclusive breastfeeding gives 2,480 kcal/day.
EER worked examples by life stage
Baby boy, 4 months, 64.4 cm, 7.2 kg
Infants have a single equation with no activity level, plus a growth allowance that is largest in the first months. Enter the age as 4 ÷ 12 = 0.33 years. The result is 589 kcal/day, the value printed in the report's infant reference table.
Girl, 3 years, 96.9 cm, 14.9 kg
At 3 the child equations and activity levels begin. The EER runs from 1,075 kcal/day inactive to 1,217 kcal/day very active, including 15 kcal/day for growth.
Woman, 75, 160 cm, 65 kg, low active
The adult equations cover everyone aged 19 and over. Her EER is 1,895 kcal/day. At 45 with the same body it would be 2,105 kcal, because the women's equations subtract 7.01 kcal for every year of age.
How many calories a day you need by age
This table holds body size constant and changes only age, so it shows the age term on its own. Men lose 10.83 kcal/day per year and women 7.01, in every activity category. Real people also change weight and activity as they age, so enter your own numbers above.
| Age | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
|---|---|---|---|---|---|---|---|
| Man, 175 cm / 80 kg | 3,013 | 2,904 | 2,796 | 2,688 | 2,579 | 2,471 | 2,363 |
| Woman, 162 cm / 68 kg | 2,330 | 2,260 | 2,190 | 2,120 | 2,050 | 1,980 | 1,910 |
Breastfeeding calorie calculator: what changes
NASEM builds the lactation EER from three parts: your non-pregnant energy expenditure, the energy cost of making milk, and, in the first 6 months, energy mobilized from body tissue. Exclusive breastfeeding (0–6 months) is 540 kcal for milk minus 140 kcal mobilized, a net 400 kcal/day. Partial breastfeeding (7–12 months) adds 380 kcal/day with no mobilization term. The report adds nothing in the first trimester of pregnancy, where it treats energy deposition as negligible.
| Status | Inactive | Low active | Active | Very active |
|---|---|---|---|---|
| Not breastfeeding | 2,080 | 2,244 | 2,381 | 2,614 |
| Exclusive, 0–6 mo | 2,480 | 2,644 | 2,781 | 3,014 |
| Partial, 7–12 mo | 2,460 | 2,624 | 2,761 | 2,994 |
EER compared with Mifflin-St Jeor and TDEE
Most TDEE calculators take a resting equation such as Mifflin-St Jeor and multiply it by an activity factor. Mifflin, St Jeor and colleagues derived their equation in 1990 from indirect calorimetry in 498 healthy adults aged 19–78, both normal weight and obese: resting energy = 10 × kg + 6.25 × cm − 5 × age, + 5 for men or − 161 for women (PubMed 2305711). It predicts energy at rest, not total daily need.
The 2023 EER equations skip the multiplier and predict total energy expenditure directly from doubly labeled water data. NASEM explains why: the physical activity coefficient is not constant but varies significantly across age groups, so a single set of multipliers could not serve every life stage. For the 40-year-old man in the first example, Mifflin gives 1,778 kcal/day at rest. His low active EER of 2,912 kcal is 1.64 times that, which the calculator shows alongside your result. A gap of a couple of hundred calories between a TDEE tool and this EER is smaller than the EER's own prediction error: about 339 kcal/day for men and 246 for women.
Turning your EER into macronutrients
For adults the calculator also splits your EER using the Acceptable Macronutrient Distribution Ranges: 45–65% of energy from carbohydrate, 10–35% from protein and 20–35% from fat. It converts them to grams at 4 kcal per gram for carbohydrate and protein and 9 for fat, as StatPearls' nutrients chapter gives. At 2,500 kcal/day that is 281–406 g of carbohydrate, 63–219 g of protein and 56–97 g of fat. These ranges are wide on purpose; any mix inside them is consistent with the DRIs.
EER for NASEM reference people
| Person | Height / weight | Inactive | Low active | Active | Very active |
|---|---|---|---|---|---|
| Man, 25 | 176.1 cm / 81.4 kg | 2,775 | 2,988 | 3,177 | 3,516 |
| Man, 60 | 174.9 cm / 88.7 kg | 2,491 | 2,709 | 2,907 | 3,258 |
| Woman, 25 | 162.7 cm / 69.3 kg | 2,152 | 2,316 | 2,454 | 2,683 |
| Boy, 10 | 141.1 cm / 38.7 kg | 1,959 | 2,082 | 2,252 | 2,460 |
| Girl, 12 | 154.3 cm / 52.1 kg | 2,009 | 2,203 | 2,340 | 2,607 |
| Boy, 16 | 172.6 cm / 66.8 kg | 2,755 | 2,941 | 3,243 | 3,615 |
These match the reference tables printed in the 2023 report. Children's values include the report's energy cost of growth (15–30 kcal/day).
How to use your EER
NASEM describes planning with the EER as a two-step process: estimate the requirement, then monitor body weight over time and adjust intake if you gain or lose weight you did not intend to. Treat your result as a starting point. Because the adult equations have an error of roughly 250–340 kcal/day, eat at your EER for 2–4 weeks, check your weekly average weight, and move up or down by 100–200 kcal if needed.
To lose weight by a set date, use the weight loss by date calculator, which starts from these equations. If you lift and want to lose fat while gaining muscle, the body recomposition calculator splits calories into training and rest days.
What affects the result, and when not to use it
- Activity level has the biggest effect. Moving from inactive to very active can add over 700 kcal/day for an adult man.
- Weight and height are entered as they are now. The EER maintains current weight; it does not tell you what you "should" weigh.
- Age lowers adult EER a little each year.
- Not for illness or recovery. People who are acutely ill, recovering from surgery, have an eating disorder, or are on a medically supervised diet need individual advice.
- Children and pregnancy. Values are for healthy growth and pregnancy. Growth charts and prenatal visits are the right way to check that intake is enough.
This calculator gives general information, not medical or nutrition advice. Ask a doctor or registered dietitian for a personal plan, especially during pregnancy, for children, or if you have a medical condition.
Frequently asked questions
What is EER?
The Estimated Energy Requirement is the average daily calorie intake predicted to maintain energy balance in a healthy person of a given age, sex, height, weight and physical activity level. The National Academies' 2023 equations are built from doubly labeled water measurements of total energy expenditure.
How many calories does a 25-year-old man need?
For the NASEM reference man (25 years, 176.1 cm, 81.4 kg) the 2023 EER is 2,775 kcal/day if inactive, 2,988 low active, 3,177 active and 3,516 very active.
How many calories does a 25-year-old woman need?
For the reference woman (25 years, 162.7 cm, 69.3 kg): 2,152 kcal/day inactive, 2,316 low active, 2,454 active and 2,683 very active.
How accurate is the EER?
It is a population estimate. For adults the 2023 equations have a root-mean-square error of about 339 kcal/day for men and 246 kcal/day for women (NASEM Table S-1), so your true need can differ by a few hundred calories. Track your weight over a few weeks and adjust.
How much extra do you need when pregnant or breastfeeding?
In the 1st trimester the normal equation applies. In the 2nd and 3rd trimesters NASEM uses a pregnancy equation that adds 9.16 kcal/day per week of gestation plus an energy-deposition amount set by pre-pregnancy BMI (+300 underweight, +200 normal, +150 overweight, −50 obese). Exclusive breastfeeding (0–6 months) adds 540 − 140 = 400 kcal/day; partial breastfeeding (7–12 months) adds 380 kcal/day.
Is EER a weight-loss target?
No. EER estimates what maintains your current weight. Eating below it will usually lead to weight loss, but the body adapts. See our weight loss by date calculator for a model that accounts for this.
What is the difference between EER and BMR?
BMR (basal metabolic rate) is the energy you burn at complete rest. EER is total daily energy for maintenance, including activity. The physical activity level (PAL) is the ratio of the two: total energy expenditure divided by basal energy expenditure.
What is the difference between EER and TDEE?
Both describe the calories you burn in a day. TDEE usually means BMR multiplied by an activity factor. EER is the National Academies' estimate of the intake that keeps a person at energy balance, predicted directly from age, sex, height, weight and activity level.
Did the 2023 EER equations replace the 2005 ones?
Yes. The National Academies last updated the energy DRIs in 2005. The 2023 report has new equations and now defines the DRI population as the general population, including people with overweight, obesity and chronic diseases.
Which activity level should I choose?
Pick by how much you move on a typical day. NASEM's examples: low active is roughly daily living plus 60–80 minutes of walking at 3–4 mph; active adds about 2 hours of mixed moderate activity; very active adds more vigorous work such as jogging. Most people with desk jobs and no regular exercise are inactive or low active.
How many calories should I eat while breastfeeding?
NASEM adds 400 kcal/day to your non-pregnant EER while exclusively breastfeeding in the first 6 months (540 kcal for milk production minus 140 kcal drawn from body stores) and 380 kcal/day for partial breastfeeding at 7–12 months. For a 30-year-old, 165 cm, 65 kg inactive woman that is 2,480 kcal/day exclusive and 2,460 kcal/day partial.
Is EER the same as maintenance calories?
In practice, yes. The EER is the intake predicted to keep a person at energy balance, which is what most people mean by maintenance calories. It is an average for people like you, so confirm it by watching your weight for a few weeks.
Is the EER higher or lower than Mifflin-St Jeor?
They measure different things. Mifflin-St Jeor predicts resting energy expenditure; the EER is total daily need. For a 40-year-old, 5′10″, 190 lb man, Mifflin gives about 1,778 kcal at rest and the low active EER is 2,912 kcal, about 1.64 times higher.
How many calories does a 10-year-old need?
For the NASEM reference boy (10 years, 141.1 cm, 38.7 kg) the EER is 1,959 kcal/day inactive to 2,460 kcal/day very active, including the energy cost of growth.
Sources & method
- National Academies (2023) — Dietary Reference Intakes for Energy, Summary (EER equations, Tables S-1 to S-6)
- National Academies (2023) — Chapter 5, physical activity level categories (Table 5-4)
- National Academies (2023) — Chapter 7, applications and reference EER tables (Tables 7-1, 7-5 to 7-10)
- PubMed — Dietary Reference Intakes for Energy (2023), doi:10.17226/26818
- Mifflin et al. (1990), Am J Clin Nutr — A new predictive equation for resting energy expenditure (PubMed)
- National Academies — Dietary Reference Intakes: Macronutrients summary table (AMDR)
- StatPearls (NCBI Bookshelf) — Biochemistry, nutrients (4, 4 and 9 kcal per gram; AMDR)
Results are estimates for general information. Found an error? It helps everyone — see our methodology.