CalcOS calculator
Calorie Calculator
Estimate an adult's daily maintenance energy from age, sex, body size, and an activity estimate.
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How this calculator works
Estimate an adult maintenance-calorie starting point from the Mifflin-St Jeor resting-energy equation and a selected activity factor. This educational estimate is not a prescription or medical advice.
- Method
- Total Daily Energy Expenditure (TDEE) estimation scaled by Physical Activity Level (PAL)
- Source
- Mifflin et al. (1990); NIH/NIDDK Body Weight Planner scope and limitations
- Last reviewed
- 2026-08-24
Method limitations
- The equation predicts resting energy for adults; it does not measure an individual's metabolism.
- The selected activity factor is a coarse estimate and can materially overstate or understate maintenance energy.
- Not for people under 19, pregnancy, breastfeeding, diagnosis, treatment, or an individualized eating prescription.
- Linear target-date weight forecasts are not certified and are not provided by the bounded experience.
Engine-backed example
Adult maintenance-calorie estimate: worked example
What is the estimated maintenance energy for a 25-year-old man who is 70 kg, 175 cm, and lightly active?
- Adult inputs
- Male, age 25
- Body size
- 70 kg and 175 cm
- Selected activity
- Lightly active (factor 1.375)
Maintenance Calories2,301 kcal/day
- Estimated Resting Energy
- 1,674 kcal/day
- Selected Activity Factor
- 1.375
- Illustrative ±15% Range
- 1,956–2,647 kcal/day
Mifflin-St Jeor predicts about 1,674 kcal/day of resting energy. Multiplying by the selected 1.375 activity factor gives an estimated maintenance starting point of 2,301 kcal/day.
Trust and review
Who created and reviewed this calculator?
- Author
- CalcOS Editorial TeamResponsible for adult-scope calculator explanations, assumptions, examples, and non-diagnostic wording.
- Reviewed by
- CalcOS Scientific ReviewTechnical review of adult Mifflin-St Jeor resting-energy prediction, unit conversion, activity-factor multiplication, applicability boundaries, engine parity, and health-safety communication; not individualized medical or dietetic advice.
- Substantive review date
- 2026-08-24Adults age 19–100, Mifflin-St Jeor equation, metric/imperial equivalence, selected activity factor, rounding, uncertainty communication, exclusions, and worked-example parity.
Sources
- Mifflin et al. (1990) — adult resting-energy prediction equation
- NIH/NIDDK — Body Weight Planner adult scope and limitations
- CDC — Steps for Losing Weight
- National Academies — Dietary Reference Intakes for Energy (2023)
Assumptions used by this calculator
- The calculator is for adults age 19–100 and is not intended for pregnancy or breastfeeding.
- Resting energy is predicted, not measured, using the sex-specific Mifflin-St Jeor equation.
- Maintenance energy multiplies predicted resting energy by the user-selected activity factor.
- The activity factor and illustrative range are coarse estimates, not a calorie prescription.
- Medical conditions, medications, body composition, and individual physiology can materially change energy needs.
- The bounded experience does not provide a target-date weight forecast or individualized deficit/surplus recommendation.