Calorie Calculator
Estimate your daily caloric needs based on your age, gender, weight, height, and activity level using the Mifflin-St Jeor equation.
How to Use
- Enter your age, gender, weight, and height.
- Select your typical activity level from the dropdown.
- Click "Calculate Calories" to see your daily calorie needs.
- Use the results to plan your diet for weight loss, maintenance, or gain.
How It Works
This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR). For men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161. The BMR is then multiplied by an activity factor to estimate Total Daily Energy Expenditure (TDEE). A deficit of 500 calories per day leads to roughly 1 lb of weight loss per week.
What Is a Calorie Calculator?
A calorie calculator estimates how many calories your body needs each day to maintain, lose, or gain weight. Calories are units of energy that fuel everything you do, from breathing and sleeping to running and lifting weights. The number you need depends on your age, gender, body size, and how physically active you are throughout the day.
This tool uses the Mifflin-St Jeor equation, which researchers have found to be the most reliable formula for estimating daily calorie needs in most adults. It first calculates your Basal Metabolic Rate (BMR) — the energy your body uses at complete rest — and then adjusts it based on your activity level to give you a Total Daily Energy Expenditure (TDEE). From there, you can subtract 500 calories per day for steady weight loss of about one pound per week, or add 500 calories for controlled weight gain. Understanding your calorie needs is the foundation of any effective nutrition plan, whether your goal is fat loss, muscle building, or simply maintaining your current weight.
Frequently Asked Questions
How accurate is this calorie calculator?
The Mifflin-St Jeor equation is considered the gold standard for calorie estimation and is accurate within about 10% for most people. However, individual metabolism varies based on genetics, muscle mass, hormones, and other factors. Use the result as a starting point and adjust based on your real-world results over 2 to 4 weeks.
Should I eat my exercise calories back?
If you selected an activity level that reflects your exercise habits, your calorie estimate already accounts for that activity. Eating back additional exercise calories on top of that could lead to eating more than intended. If you track exercise separately, start by eating back about half of those calories and adjust from there.
Is 1,200 calories a day enough?
For most adults, eating fewer than 1,200 calories per day is not recommended without medical supervision. Very low-calorie diets can cause nutrient deficiencies, muscle loss, and metabolic slowdown. If this calculator suggests fewer than 1,200 calories for weight loss, consider a smaller deficit or increasing your activity level instead.
How much weight will I lose at a 500-calorie deficit?
A daily deficit of 500 calories adds up to about 3,500 calories per week, which roughly equals one pound of fat loss. In practice, weight loss is rarely perfectly linear due to water retention, hormonal fluctuations, and metabolic adaptation. Consistency over weeks and months matters more than any single day.
Does my calorie need change as I lose weight?
Yes, as you lose weight your body requires fewer calories to maintain itself. It's a good idea to recalculate your calorie needs every 10 to 15 pounds of weight loss to make sure your plan stays on track. This is one reason weight loss often slows down over time.
Example Calculation
Consider a 30-year-old male who weighs 180 lbs (81.6 kg), stands 5'10" (177.8 cm), and exercises 3 to 5 days per week (moderately active). His BMR using the Mifflin-St Jeor equation is: 10 × 81.6 + 6.25 × 177.8 - 5 × 30 + 5 = 816 + 1,111 - 150 + 5 = 1,782 calories/day. Multiplied by the moderate activity factor of 1.55, his TDEE is approximately 2,762 calories/day. To lose one pound per week, he would target about 2,262 calories per day. To gain weight steadily, he would aim for around 3,262 calories per day.