Daily Calorie (Energy) Needs Calculator

What the Estimated Energy Requirement means

The result on this page is an Estimated Energy Requirement, or EER. The National Academies of Sciences, Engineering, and Medicine (NASEM) define the EER as the average dietary energy intake predicted to maintain energy balance in an adult of a defined age, sex, weight, height and level of physical activity. It is expressed in kilocalories (kcal) per day.

"Energy balance" means intake equals what the body uses. NASEM's tables say that for weight-stable adults, EER equals total energy expenditure. In other words, the equations estimate how much energy a person like you uses in a day, including movement.

This is why it is not the same as basal metabolic rate. The EER equations take physical activity level into account, which basal metabolic rate does not.

The 2023 report says the earlier energy reference values had last been updated in 2005.

The report also describes a two-step process: calculate the EER, then monitor body weight over time and adjust intake if unwanted weight gain or loss occurs.

Walking through the equation

Each equation has the same shape: a starting number, minus an amount for each year of age, plus an amount for each centimeter of height, plus an amount for each kilogram of weight. The units are age in years, weight in kilograms and height in centimeters.

Age lowers the estimate in every equation: by 10.83 kcal per year for men and 7.01 kcal per year for women. Height and weight raise it. The coefficients for height and weight are different for each of the four activity levels, so choosing a more active level changes more than one term.

As a small check, take the low active equation for women: 575.77 − 7.01 × age + 6.60 × height + 12.14 × weight. For a woman who is 10 years older with the same height and weight, the result is 7.01 × 10 = 70.1 kcal lower.

The report's own worked example is a 22-year-old woman, 165 cm and 63 kg, with a low active level: 575.77 − 154.22 + 1,089.00 + 764.82 = 2,275.37, which the report gives as 2,275 kcal per day. The calculator reproduces this figure.

The report's Table S-1 gives the equations as predictions of total energy expenditure (TEE), which equals the EER for weight-stable adults. Its notes report a root mean squared error (RMSE), roughly a typical size of the gap between predicted and measured values in the data used: 246 kcal per day for women and 339 kcal per day for men. We cannot turn that into a personal margin of error, but it shows the estimate is an average, not an exact figure.

Worked examples

All four activity levels are shown for each person, as the calculator does. The sentence "About ... kcal per day" rounds the chosen level's result to the nearest 10 kcal.

kcal per day. Computed with the same steps as the calculator on this page.

Steps for the man, low active: 581.47 − 10.83 × 60 + 8.30 × 175 + 14.94 × 80 = 581.47 − 649.80 + 1,452.50 + 1,195.20 = 2,579.37. The headline reads 2,579 and "About 2,580 kcal per day".

For the US-unit case, the calculator first converts 64 in to 162.56 cm and 140 lb to 63.50 kg. Low active: 575.77 − 350.50 + 1,072.90 + 770.93 = 2,069.09, shown as 2,069.

The first row matches the example in the National Academies of Sciences, Engineering, and Medicine (NASEM) report: 2,275 kcal per day for a 22-year-old woman, 165 cm, 63 kg, low active.

Choosing an activity level

The National Academies of Sciences, Engineering, and Medicine (NASEM) groups adults into four physical activity level (PAL) categories: inactive (1.00 up to below 1.53), low active (1.53 to below 1.68), active (1.68 to below 1.85) and very active (1.85 to below 2.50). Some tables in the report print 1.69 instead of 1.68 as the low active and active boundary. The difference is small.

"Inactive" does not mean no movement. NASEM says people in this category are not completely sedentary but are minimally active beyond what is involved in daily living and do little or no occupational physical activity.

NASEM's Table 7-1 gives example days. Daily living means 30 minutes of walking plus about 90 minutes of light to moderate activity, such as household tasks. Low active adds 60 to 80 minutes of walking at 3 to 4 mph. Active adds 30 to 50 minutes of walking, 45 minutes of moderate cycling and 40 minutes of doubles tennis. Very active adds 45 minutes of moderate cycling, about 25 minutes of jogging and 60 minutes of doubles tennis.

The report adds that the examples may be most appropriate for people in occupations that need little physical exertion, such as office work. It says other activities can be substituted. It also says that at present it appears no valid, reliable tool exists to classify an individual's PAL category accurately, and it offers Table 7-1 as guidance. So pick the description that fits your usual day, and expect some error.

Limits, and why results differ from other calculators

The National Academies of Sciences, Engineering, and Medicine (NASEM) says the EER equations reflect estimated requirements for weight maintenance and do not predict the energy needed to lose or gain weight. That is why this calculator does not give weight-loss or weight-gain calorie targets. The report describes a separate method for identifying intakes likely to lead to weight change. We do not present it here, because a simple form cannot apply it safely.

Other calculators may use different equations. An older set, from the Institute of Medicine in 2005, takes height in meters and uses an activity multiplier instead of separate coefficients, for example for men 662 − 9.53 × age + PA × (15.91 × weight + 539.6 × height). The 2023 equations use height in centimeters and a different age term (10.83 kcal per year for men versus 9.53 in 2005). The two sets use different inputs and units, so their coefficients should not be mixed in one calculation.

Individuals also vary around the average. NASEM says requirements differ among people with the same age, height, weight and activity category, and advises monitoring body weight over time and adjusting intake if unwanted gain or loss occurs.

The calculator is for adults 19 and older. It is not designed for pregnancy or breastfeeding.

Edge cases and what to discuss with a professional

The form refuses ages under 19. It also checks that age is at most 110, height is 100 to 230 cm (about 39.4 to 90.5 inches) and weight is 30 to 300 kg (about 66.2 to 661 pounds). Values outside these ranges show a message instead of a number.

The headline shows the estimate rounded to the nearest whole number, and the sentence "About ... kcal per day" rounds to the nearest 10. For the first example these are 2,275 and about 2,280.

Because the National Academies of Sciences, Engineering, and Medicine (NASEM) reports that individual requirements can differ from the estimate, a number from this page is best treated as a starting point. NASEM's own advice is to monitor body weight over time and adjust intake as needed.

Questions to bring to a doctor or registered dietitian: whether your activity level has been picked fairly; whether you have a health condition, medicine or life stage that changes energy needs; and how to set any weight goal safely. This page is general information, not medical advice.