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Daily calorie needs calculator: energy requirement and resting estimate

Estimate an adult's daily energy requirement with a current 2023 DRI equation, then see a separately calculated Mifflin–St Jeor resting-energy estimate without treating either result as a prescription.

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Calculate your result

Choose the equation set

The published daily-energy and resting-energy equations use female and male study categories. Choose the equation set that applies to the calculation, not as a judgement about identity. If neither is appropriate, do not rely on this estimate.

Choose the 2023 DRI calculation category that best reflects usual daily life. The examples are approximate and are not exercise recommendations.

Enter completed years. This version is limited to ages 19 to 78, matching the original study sample.

Accepted range: 19 to 78 years

Enter a current measured weight. The accepted range is a technical limit, not a health category.

Accepted range: 25 to 300 kg

Enter standing height without shoes. The accepted range is a technical limit, not a health category.

Accepted range: 100 to 250 cm

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What this result means

Daily energy expenditure includes energy used at rest plus activity and other demands. This calculator uses the 2023 National Academies adult equation for the main daily estimate and calculates Mifflin–St Jeor resting energy separately; it does not multiply one model by an unrelated activity factor. [1][2][7]

Daily energy and resting energy use separate models

The main result uses the 2023 National Academies adult equation for the selected activity category. It predicts daily energy expenditure directly from age, height and weight; it is not created by multiplying a resting estimate. [2][7]

The separate Mifflin–St Jeor number predicts resting energy and is often called BMR online. It is not a measured metabolic rate, an activity allowance or a component to add to the main result. [1]

What the activity categories mean

For adults, the 2023 model uses four physical-activity categories: inactive at PAL 1.00 to under 1.53, low active at 1.53 to under 1.68, active at 1.68 to under 1.85, and very active at 1.85 to under 2.50. Each category has its own equation. [2][4]

Choose the category that best reflects usual life over time. The activity examples are calculation aids, not health recommendations, and one unusually active day or hard workout does not establish a category. [4][8]

Why the result is an estimate, not an exact target

The adult male equations reported RMSE 339 kcal/day, MAE 266 kcal/day and MAPE 9.4%; the adult female equations reported RMSE 246 kcal/day, MAE 191 kcal/day and MAPE 8.7%. These are model-performance statistics, not a personal confidence interval. [2][7]

Body composition, illness, medicines, recent weight change, environment and the activity category can all affect the gap between an equation and real expenditure. LongevityMate rounds the result and does not present it as calories you must eat.

Why the calculator asks for a female or male equation set

Both cited models publish separate female and male equation sets. The selector chooses mathematical coefficients; it is not an inference about identity, and this version does not invent an unsupported neutral average. [1][2]

If neither equation set is appropriate for your situation, or if hormones, surgery, illness or body composition make the model uncertain, do not rely on the estimate for a decision.

Units and careful rounding

One international pound is exactly 0.45359237 kilograms and one inch is exactly 2.54 centimetres. One kilocalorie is 4.184 kilojoules. [3][6]

LongevityMate converts units before calculation, rounds the daily estimate to the nearest 50 kcal/day and 200 kJ/day, and rounds the separate resting estimate to the nearest 10 kcal/day. The coarser display reflects model uncertainty rather than calculator precision.

This model comes from United States and Canadian guidance

The main equations were developed for United States and Canadian dietary reference guidance using doubly labelled water data. Health Canada uses the same adult equations and warns that its calculation categories are not physical-activity health guidelines. [2][4][7][8]

Australia's Eat For Health calculator similarly frames daily requirements as estimates that depend on age, body size and activity and commonly reports energy in kilojoules. [5][6]

This worldwide English page labels that jurisdiction instead of presenting the model as a universal national recommendation. Follow local professional guidance when an intake decision matters.

A safe next step

Treat the result as rough orientation. If food intake, weight change, illness, training, pregnancy, an eating concern or medication makes the question important, discuss it with a qualified clinician or dietitian rather than acting on this estimate alone. [4][5]

Formula and assumptions

Formula
Daily energy = the selected 2023 adult EER equation: intercept − age coefficient × age + height coefficient × height(cm) + weight coefficient × weight(kg). Resting energy = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + the selected Mifflin equation constant. [1][2][3][7]
Version
2023 adult DRI energy equation with a separate Mifflin–St Jeor resting estimate, nasem-2023-adult-eer-plus-mifflin-ree-v1
Rounding
Normalize units with exact SI factors and calculate each model independently with exact decimal rational arithmetic. Round daily energy to the nearest 50 kcal/day and 200 kJ/day; round resting energy to the nearest 10 kcal/day.
Worked example
For the male equation set, age 19, 70.0 kg, 175.0 cm and the active category, the 2023 daily-energy equation gives 1,004.82 − (10.83 × 19) + (6.52 × 175) + (15.91 × 70) = 3,053.75 kcal/day, displayed as 3,050. The separate Mifflin resting equation gives 1,703.75 kcal/day, displayed as 1,700. The resting number is not multiplied or added to the daily estimate.

Who this is for — and when not to use it

Intended use

Adults aged 19 to 78 who want a transparent educational estimate of daily energy from the 2023 U.S./Canada adult DRI model and a separately calculated Mifflin–St Jeor resting estimate.

Not intended for

This tool does not measure metabolism, prescribe calorie or kilojoule intake, provide deficit or surplus targets, plan weight change, calculate macros or meals, estimate a particular workout, support athletic fueling, diagnose a condition or replace clinical nutrition care.

Exclusions

  • Anyone under age 19 or over age 78
  • Pregnancy, breastfeeding or postpartum energy planning
  • A diagnosed or suspected eating disorder, severe undernutrition or use that could reinforce calorie fixation
  • Acute illness, recovery, metabolic or endocrine disease, substantial oedema or another situation requiring clinical nutrition assessment
  • Highly specialized athletic fueling or very unusual body composition
  • Deficit, surplus, weight-change timeline, meal, macro, minimum-intake, treatment or diagnosis decisions

Evidence sources

  1. 1. A new predictive equation for resting energy expenditure in healthy individuals — American Journal of Clinical Nutrition. Accessed Aug 17, 2026.
  2. 2. TEE prediction equations by age, sex and life-stage group (Table S-1) — National Academies of Sciences, Engineering, and Medicine. Accessed Aug 17, 2026.
  3. 3. NIST Guide to the SI, Appendix B conversion factors — National Institute of Standards and Technology. Accessed Aug 17, 2026.
  4. 4. Dietary reference intake equations and adult physical-activity categories — Health Canada. Accessed Aug 17, 2026.
  5. 5. Daily energy requirements calculator — Australian Government Eat For Health. Accessed Aug 17, 2026.
  6. 6. Kilojoules and daily energy needs — Australian Government healthdirect. Accessed Aug 17, 2026.
  7. 7. Dietary Reference Intakes for Energy — National Academies of Sciences, Engineering, and Medicine. Accessed Aug 17, 2026.
  8. 8. Dietary Reference Intakes Calculator — Health Canada. Accessed Aug 17, 2026.