Calorie Calculator
Calculate your basal metabolic rate and the daily calories you need to maintain your current weight.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
Daily calorie needs start from your basal metabolic rate — the energy your body burns at complete rest — and multiply it by an activity factor. The Mifflin-St Jeor equation used here is the most accurate of the simple predictive formulas for most adults.
Worked example
calculated with the default values below
Sex Male · Age 30 years · Height 178 cm · Weight 80 kg · Activity level Moderate — exercise 3-5 days a week Maintenance estimate 2,740 kcal/day · Estimated resting energy 1,768 kcal/day · Example: 550 kcal below 2,190 kcal/day · Example: 550 kcal above 3,290 kcal/day
Method and assumptions
Formula basis and scope
The resting-energy component uses the rounded Mifflin–St Jeor equation; the activity option multiplies that estimate.
The cited study supports resting energy, not the activity multipliers or the fixed ±550 kcal scenarios. Those are planning assumptions, not prescribed weight-change targets.
Data sources
Disclaimer
These calculators are for general information only and are not a medical device, a diagnosis or a treatment plan. Reference ranges describe populations, not individuals, and do not account for pregnancy, medication, disability or athletic training. Discuss your own situation with a qualified healthcare professional.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
RMR = 10w + 6.25h − 5a + s; TDEE = RMR × k
- w
- Weight, kg
- h
- Height, cm
- a
- Age, years
- s
- Sex constant: +5 male, −161 female
- k
- Activity factor 1.2–1.9
- RMR
- Estimated resting metabolic rate
- TDEE
- Total daily energy expenditure
Mifflin–St Jeor estimates resting metabolic rate for adults in the study population aged 19–78 in the original study; activity multipliers and ±550 kcal/day are rough scenarios, not individualized advice.
Frequently asked questions
How fast can I lose weight safely?
This calculator does not determine a safe rate of weight loss. It estimates energy needs from the selected inputs and activity factor; it does not assess age, pregnancy, medical conditions, medications or nutritional adequacy. Discuss a calorie target or planned weight change with a qualified health professional, especially if you are under 18 or have a medical condition.
Why has my weight loss stalled?
The calculator cannot identify why weight changed or stalled. Its result is an estimate based on the values and activity factor entered, not a measurement of your energy expenditure. Day-to-day scale changes and individual needs are not modeled; avoid making large dietary changes from this estimate alone.