Calorie Calculator (TDEE)
Find out exactly how many calories you need each day — for weight loss, maintenance or muscle gain — based on your age, body and activity level.
What is it?
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, accounting for your basal metabolic rate plus the energy you use through physical activity. Knowing your TDEE is the single most important number in any nutrition plan: eat below it and you lose weight, eat at it and you maintain, eat above it and you gain. This free calorie calculator uses the Mifflin-St Jeor equation — the formula most consistently recommended by nutrition researchers and dietitians because it outperforms older models like Harris-Benedict on real-world accuracy. It first calculates your Basal Metabolic Rate (BMR), the calories your body needs just to stay alive at rest — for breathing, circulation and cell repair — then multiplies by an activity factor that reflects how much you actually move during the day. The result is your maintenance TDEE, along with five calorie targets: aggressive loss (−750 kcal), moderate loss (−500 kcal), mild loss (−250 kcal), maintenance, and a lean bulk (+250 kcal). The tool supports both metric and imperial units and adjusts for biological sex, which affects the BMR constant in the Mifflin-St Jeor formula.
How to use it
- Select your biological sex (male or female) — this affects the BMR offset in the formula.
- Enter your age in years.
- Select your unit system (Metric: cm and kg, or Imperial: ft/in and lbs).
- Enter your height and current body weight.
- Choose your activity level from the five options: Sedentary, Lightly Active, Moderately Active, Very Active or Extra Active.
- Your BMR and TDEE are calculated instantly. Read the calorie targets table for weight loss and gain options.
- Use the Protein/Fat/Carb split panel to get a macronutrient breakdown for your chosen target.
Why use this tool
Generic calorie advice — "eat 2,000 calories a day" — ignores the fact that a 25-year-old male athlete and a 55-year-old sedentary woman have almost nothing in common nutritionally. The Mifflin-St Jeor formula personalises the calculation to your specific body and lifestyle, making it far more accurate than a fixed number or a simple rule of thumb. Understanding your TDEE removes the guesswork from dieting. Instead of arbitrarily cutting food or following a plan designed for someone else, you have a concrete number to work with. A 500 kcal daily deficit, maintained consistently, produces approximately 0.5 kg (1 lb) of fat loss per week — a rate that is sustainable and backed by decades of metabolic research. The macronutrient panel is equally useful: protein needs (roughly 1.6–2.2 g per kg of body weight for active individuals) drive muscle retention during a cut, and seeing your targets in grams makes meal planning concrete rather than abstract. All calculations run locally in your browser — no account, no tracking, no ads.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep you alive. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor, giving the total calories you burn on a typical day including movement and exercise.
Which activity level should I choose?
Sedentary: desk job, little or no exercise. Lightly active: light exercise 1–3 days/week. Moderately active: moderate exercise 3–5 days/week. Very active: hard exercise 6–7 days/week. Extra active: physical job or twice-daily training. Most people overestimate their activity level — when in doubt, choose one step lower.
How accurate is the Mifflin-St Jeor formula?
Studies show it predicts BMR within about 10% for most adults. No formula is perfectly accurate because individual metabolism varies. Treat your TDEE as a starting estimate, track your actual weight change over 2–3 weeks, and adjust calories by 100–200 kcal if results differ from expected.
How fast can I safely lose weight?
A deficit of 500 kcal per day produces roughly 0.45–0.5 kg (1 lb) per week. Deficits larger than 750–1,000 kcal risk muscle loss, nutrient deficiencies and metabolic adaptation. Most guidelines recommend losing no more than 0.5–1% of body weight per week.
Does this calculator work for children or pregnant women?
No. The Mifflin-St Jeor formula is validated for adults aged 18–65. Children have different metabolic needs, and pregnancy significantly changes calorie requirements. Consult a paediatrician or registered dietitian for these groups.