About This Tool
The Calorie Calculator estimates your total daily energy expenditure (TDEE)—the number of calories you need each day to maintain your current weight based on your activity level. It starts by calculating your BMR (using the Mifflin-St Jeor equation) and then multiplies it by an activity factor that ranges from sedentary (little or no exercise) to extra active (very hard exercise/physical job). This tool is invaluable for anyone looking to manage their weight: if you eat more than your TDEE, you gain weight; if you eat less, you lose weight. Common use cases include setting a calorie target for weight loss or muscle gain, planning meal portions, and understanding how activity level impacts your energy needs. It takes the guesswork out of dieting by providing a science-backed starting point.
How It Works
First, your BMR is calculated using the Mifflin-St Jeor formula based on sex, weight, height, and age. Then, BMR is multiplied by an activity factor: Sedentary (1.2), Lightly active (1.375), Moderately active (1.55), Very active (1.725), or Extra active (1.9). The result is your TDEE in calories per day. For example, a sedentary woman with a BMR of 1,370 calories has a TDEE of 1,370 × 1.2 = 1,644 calories/day. To lose weight, she would subtract 300–500 calories from this number.
Examples
- A 30-year-old woman who weighs 70 kg, is 165 cm tall, and exercises 3–4 times per week (moderately active): BMR = 1,444 calories. TDEE = 1,444 × 1.55 ≈ 2,238 calories/day. To lose 0.5 kg per week, she should aim for about 1,738 calories daily.
- A 40-year-old man who weighs 90 kg, is 180 cm tall, and has a desk job (sedentary): BMR = 1,870 calories. TDEE = 1,870 × 1.2 = 2,244 calories/day. For weight maintenance, he should eat around 2,244 calories; for weight loss, around 1,944 calories.
Pro Tips
- Be honest about your activity level. Most people overestimate how active they are, which leads to overeating. If in doubt, choose a lower activity level.
- Your TDEE is an estimate. Track your weight for 2–3 weeks eating at that calorie level, then adjust up or down by 100–200 calories if your weight isn't changing as expected.
- Re-calculate your TDEE every 5–10 kg (10–20 lbs) of weight loss, as your BMR decreases with weight, so your calorie needs will change.