How Many Calories Do You Burn?
Your body uses energy around the clock — to keep your heart beating, maintain body temperature, repair cells and power every movement. The total is called your Total Daily Energy Expenditure (TDEE). Eat roughly that many calories and your weight tends to stay stable; eat less and you gradually lose weight; eat more and you gain. This calculator estimates your TDEE in two steps.
Step 1 — Basal metabolic rate (BMR)
BMR is the energy your body needs at complete rest. We use the Mifflin-St Jeor equation, published in 1990, which studies have found to be among the most accurate predictive equations for healthy adults:
Notice that age appears in the formula: for the same height and weight, BMR falls by about 5 calories per day for every year of age, largely because of gradual changes in muscle mass and organ metabolism.
Step 2 — Activity multiplier
BMR is multiplied by an activity factor to account for daily movement and exercise:
| Activity level | Multiplier | Typical lifestyle |
|---|---|---|
| Sedentary | 1.2 | Desk job, little exercise |
| Lightly active | 1.375 | Light exercise 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days a week |
| Very active | 1.725 | Hard exercise 6–7 days a week |
| Extremely active | 1.9 | Physical job plus daily training |
Most people overestimate their activity level. If you are unsure, choose the lower option — it is easier to add calories later than to wonder why progress has stalled.
Worked example
A 35-year-old woman who is 170 cm tall and weighs 70 kg has a BMR of 10 × 70 + 6.25 × 170 − 5 × 35 − 161 ≈ 1,427 kcal. With light activity (× 1.375) her maintenance intake is about 1,960 kcal per day. A moderate deficit of 500 kcal gives a target of roughly 1,460 kcal.
Setting a sensible target
- Lose gradually. A deficit of 250–500 kcal a day is a common recommendation for steady, sustainable loss of about 0.25–0.5 kg (0.5–1 lb) per week.
- Prioritise protein and fibre. They help you feel full and preserve muscle while eating less.
- Re-calculate as you change. Your TDEE drops as your weight drops, so update your numbers every few kilograms.
- Get advice for special situations. Pregnancy, breastfeeding, diabetes, eating disorders and other medical conditions need individual guidance from a doctor or registered dietitian.
Frequently Asked Questions
How accurate is this calculator?
Predictive equations like Mifflin-St Jeor are typically within about 10% of measured metabolic rate for most healthy adults, but individuals vary. Use the result as a starting point and adjust based on how your weight actually changes.
What is the difference between BMR and TDEE?
BMR is the energy needed at complete rest. TDEE adds the energy used for daily activity, exercise and digesting food — it is the number to use for maintenance.
Why do calorie needs fall with age?
Muscle mass tends to decline gradually with age, and activity levels often drop. Both reduce energy use. Strength training and staying active help slow this change.
Is a 1,200-calorie diet safe?
Very low intakes can make it hard to meet nutrient needs and are not appropriate for everyone. This tool never suggests targets below about 1,200 kcal for women or 1,500 kcal for men; speak to a professional before going lower.
Disclaimer: This calculator provides general information only and is not a substitute for professional medical advice, diagnosis or treatment. Formulas are population averages and may not fit your individual situation. Always consult a qualified healthcare provider about your health.
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