What it does
The Maintenance Calorie Calculator estimates the number of calories you need to eat each day to maintain your current weight. It does this by combining two values:
- Basal Metabolic Rate (BMR) — the calories your body burns at complete rest just to keep your organs functioning.
- Activity Multiplier — a factor that accounts for how much you move throughout the day, from desk-bound sedentary to multiple daily training sessions.
The result — your Total Daily Energy Expenditure (TDEE) — is the number of calories that keeps your weight stable. Eat below it to lose weight; eat above it to gain.
The science: Mifflin–St Jeor equation
The calculator uses the Mifflin–St Jeor equation, first published in the American Journal of Clinical Nutrition in 1990. In multiple independent validations it has been shown to be more accurate than older formulas (such as the original 1919 Harris–Benedict equation) for predicting resting metabolic rate in modern adults.
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
The BMR is then multiplied by an activity factor (ranging from 1.2 for sedentary to 1.9 for very active) to produce TDEE.
Key features
Completely private
No account required. No data is sent to any server. Everything runs locally in your browser.
Imperial & metric
Enter height in feet/inches or centimetres, and weight in pounds or kilograms.
Goal guidance
Alongside maintenance calories, you get estimates for gradual weight loss and gain (±500 Cal/day).
Macronutrient split
A suggested protein, fat, and carbohydrate breakdown (in grams) based on your calorie target.
Food calorie table
A searchable reference table of common foods with calorie, protein, fat, and carb counts.
Saves your profile
Your inputs are saved in your browser's localStorage so the form is pre-filled on your next visit.
Limitations to be aware of
No equation-based tool is perfect. The Mifflin–St Jeor equation produces a population average. Your actual TDEE can differ because of:
- Body composition — muscle burns more calories at rest than fat. Two people with the same height and weight can have very different metabolisms.
- Metabolic adaptation — prolonged calorie restriction causes the body to slow its metabolism in response.
- Medical conditions and medications — thyroid disease, diabetes, antidepressants, and other factors can significantly affect calorie needs.
- Activity estimation — it is difficult to estimate your true activity level; most people overestimate it.
Use the result as an informed starting point. Track your actual weight over 2–4 weeks and adjust your intake up or down by 100–200 Cal/day as needed.
How to get the most accurate result
- Weigh yourself in the morning after using the bathroom, without clothes, and use that number.
- Be honest about your activity level — if in doubt, choose one level lower than you think.
- Track your intake for 2–3 weeks without changing anything to establish your real maintenance level.
- If you want personalised guidance, consult a registered dietitian who can account for your full health picture.
References
The formulas and activity multipliers used in this calculator are based on the following published sources:
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247. doi:10.1093/ajcn/51.2.241
- Harris JA, Benedict FG. A Biometric Study of Human Basal Metabolism. PNAS. 1918;4(12):370–373. doi:10.1073/pnas.4.12.370
- U.S. Dietary Guidelines 2020–2025. dietaryguidelines.gov
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