UNDERSTAND THE METHOD
How to use this calculator
Choose the equation edition and age group. The 2023 option uses adult equations. The 2005 option includes infants, children, and adults. Activity categories are equation-specific and are not extra multipliers to add after the calculation.
What the result can tell you
These are population estimates, not measured expenditure or individual intake prescriptions. Child energy results need professional interpretation. The 2005 FatCalc convention adds 20 or 25 kcal to the child overweight branch; the published branch omits this term. Pregnancy and breastfeeding inputs are outside this calculator; the source reports separate life-stage adjustments.
Daily calories by age and activity: worked examples
These tables run the 2023 adult equations this calculator uses for two example people: a woman 163 cm (about 5 ft 4 in) tall weighing 64 kg (141 lb), and a man 178 cm (about 5 ft 10 in) tall weighing 80 kg (176 lb). These are examples, not averages or targets. Your own result depends on your height, weight, age, sex and activity level.
Woman, 163 cm, 64 kg: kcal per day
| Age | Sedentary | Low active | Active | Very active |
|---|---|---|---|---|
| 20 | 2,127 | 2,288 | 2,426 | 2,654 |
| 30 | 2,056 | 2,218 | 2,356 | 2,584 |
| 40 | 1,986 | 2,148 | 2,286 | 2,514 |
| 50 | 1,916 | 2,078 | 2,216 | 2,444 |
| 60 | 1,846 | 2,008 | 2,145 | 2,373 |
| 70 | 1,776 | 1,938 | 2,075 | 2,303 |
| 80 | 1,706 | 1,868 | 2,005 | 2,233 |
Man, 178 cm, 80 kg: kcal per day
| Age | Sedentary | Low active | Active | Very active |
|---|---|---|---|---|
| 20 | 2,821 | 3,037 | 3,222 | 3,573 |
| 30 | 2,713 | 2,929 | 3,113 | 3,465 |
| 40 | 2,605 | 2,821 | 3,005 | 3,356 |
| 50 | 2,497 | 2,713 | 2,897 | 3,248 |
| 60 | 2,388 | 2,604 | 2,788 | 3,140 |
| 70 | 2,280 | 2,496 | 2,680 | 3,031 |
| 80 | 2,172 | 2,388 | 2,572 | 2,923 |
In these equations, each extra year of age lowers the estimate by 10.83 kcal a day for men and 7.01 kcal a day for women, at every activity level. Each extra kilogram adds 14.10 to 19.11 kcal a day for men and 11.71 to 12.56 kcal a day for women, depending on activity level. The activity levels are separate equations, not multipliers added on top of a resting value.
Common questions
What is the difference between the 2023 and 2005 editions?
The 2023 option uses adult equations. The 2005 option includes infants, children, and adults with age-specific equations.
Should I add an activity multiplier after the result?
No. The activity categories are part of their selected equation and are not extra multipliers to add afterward. These are population estimates, not individual intake prescriptions.
How can I find my real TDEE?
Weigh yourself each morning and log everything you eat for at least three weeks, leaving out the first week of a new diet. Your maintenance is about your average intake plus the energy of the weight you lost, or minus the energy of the weight you gained, at about 7,716 kcal per kilogram (3,500 per pound) spread over the days. The weigh-in check on this page does the arithmetic.
Sources & limitations7 sources
Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.
- 2023 estimated energy requirement equations.canada.ca
- 2005 Dietary Reference Intakes and activity coefficients.doi.org
- Published child overweight energy equations omit the extra growth term.pmc.ncbi.nlm.nih.gov
- Adult basal and total energy equations.cdc.gov
- Wishnofsky (1958) estimated the calories in gained or lost body weight.pubmed.ncbi.nlm.nih.gov
- Hall (2008): the 3,500 kcal rule assumes all lost weight is fat tissue, water holds no energy, glycogen changes usually show within the first week, and the rule overstates the energy per kilogram for people with less body fat.pmc.ncbi.nlm.nih.gov
- Lichtman et al. (1992): people with obesity who did not lose weight on a reported low intake had under-reported intake by 47% on average.doi.org