This tool is for informational purposes only and does not constitute medical advice. Always consult a healthcare professional.
How the Calorie Calculator Works
This calorie calculator uses the Mifflin-St Jeor equation, which is widely regarded as one of the most accurate methods for estimating daily calorie needs. It first calculates your Basal Metabolic Rate (BMR) — the number of calories your body burns at rest to maintain basic life functions like breathing, circulation, and cell repair. The BMR is then multiplied by an activity factor to determine your Total Daily Energy Expenditure (TDEE), which represents the total number of calories you burn in a day.
Based on your selected goal (lose, maintain, or gain weight), the calculator adjusts the recommended calorie intake accordingly. For weight loss, it subtracts 500 calories from your TDEE (targeting approximately 0.45 kg or 1 pound of loss per week). For weight gain, it adds 500 calories. For maintenance, it recommends your TDEE as your daily target. These are general guidelines and individual needs may vary.
How to Use This Tool
- Enter your age and gender — these factors significantly affect your metabolic rate.
- Enter your height and weight — provide your height in centimetres and weight in kilograms.
- Select your activity level — choose the option that best matches your typical weekly exercise routine.
- Select your goal — choose whether you want to lose weight, maintain, or gain weight.
- Click Calculate Calories — your BMR, TDEE, and recommended daily calorie intake appear instantly.
How It Works Behind the Scenes
The Mifflin-St Jeor equation calculates BMR differently for men and women. For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5. For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161. This accounts for the metabolic differences between genders.
The TDEE is calculated by multiplying the BMR by an activity multiplier: Sedentary = 1.2, Lightly Active = 1.375, Moderately Active = 1.55, Very Active = 1.725, Extra Active = 1.9. These multipliers come from established nutritional science research. The recommended calorie intake then adjusts this TDEE based on your goal: subtract 500 for weight loss, add 500 for weight gain, or use the TDEE directly for maintenance.
Frequently Asked Questions
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is a widely used formula for estimating Basal Metabolic Rate (BMR). For men the formula is BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. For women it is BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161. Published in 1990, it is considered one of the most accurate predictive equations for estimating calorie needs in healthy adults compared to older formulas like Harris-Benedict.
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 maintain essential functions like breathing, circulation, and cell production. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor that accounts for your exercise habits and daily physical movement. TDEE represents the total number of calories you actually burn in a typical day and is the more useful number for planning your diet.
How do I choose my activity level?
Choose Sedentary if you work at a desk and do little to no exercise. Light activity means you do light exercise or sports 1-3 days per week. Moderate means regular exercise 3-5 days per week. Very active means hard exercise or sports 6-7 days per week. Extra active is for very intense daily exercise or training combined with a physically demanding job. When in doubt, choose the lower option to avoid overestimating your calorie needs.
How many calories should I eat to lose weight?
A widely recommended approach is to eat 500 calories below your TDEE each day, which typically results in about 0.45 kg (1 pound) of weight loss per week. This calculator applies this moderate deficit when you select the weight loss goal. However, calorie needs vary significantly between individuals, so it is important to consult a healthcare professional or registered dietitian before making significant changes to your diet.
How accurate is this calorie calculator?
The Mifflin-St Jeor equation has been shown in clinical studies to estimate BMR within approximately 10% for most healthy adults. However, individual variation exists due to factors such as genetics, body composition, muscle mass, hormonal balance, and metabolic adaptations. The calculated values should be treated as a starting point and adjusted based on your real-world results over several weeks of tracking.
Is my data stored?
No. All calculations are performed entirely in your browser using JavaScript. Your age, gender, height, weight, activity level, and results are never transmitted to any server or stored in any database. Once you close or refresh the page, all entered data is gone. Daytics is committed to protecting your privacy and operates all its tools completely client-side with no data collection.