Calorie Calculator
This calorie calculator determines how many calories you need per day based on your age, gender, height, weight, and activity level. Get personalized targets for weight loss, maintenance, and muscle gain using the scientifically validated Mifflin-St Jeor equation.
Frequently Asked Questions
How many calories should I eat per day?
Daily calorie needs vary based on age, gender, height, weight, and activity level. On average, adult women need 1,600-2,400 calories per day and adult men need 2,000-3,000 calories per day for weight maintenance. Use this calculator to get a personalized estimate based on the Mifflin-St Jeor equation, which is considered the most accurate predictive formula for calorie needs.
How do you calculate daily calorie needs?
Daily calorie needs are calculated by first determining your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiplying by an activity factor. For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5. For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161. The BMR is then multiplied by your activity level (1.2 to 1.9).
How many calories for weight loss?
To lose weight, you need to eat fewer calories than you burn. A safe and sustainable rate of weight loss is 1-2 pounds per week, which requires a daily deficit of 500-1,000 calories below your maintenance level. For most people, this means eating 1,200-1,800 calories per day depending on their size and activity level. Never go below 1,200 calories (women) or 1,500 calories (men) without medical guidance.
What is a calorie deficit?
A calorie deficit occurs when you consume fewer calories than your body burns in a day. Your body makes up the difference by using stored energy (primarily body fat), leading to weight loss. A deficit of 3,500 calories roughly equals one pound of fat loss. You can create a deficit by eating less, exercising more, or combining both approaches. A moderate deficit of 500 calories per day is sustainable for most people.
How many calories should I eat to gain muscle?
To gain muscle, eat a calorie surplus of 250-500 calories above your maintenance level combined with resistance training. This supports muscle protein synthesis while minimizing fat gain. Ensure adequate protein intake of 0.7-1 gram per pound of body weight. A surplus of 250 calories per day leads to approximately 0.5 pounds of weight gain per week, which is ideal for lean muscle building with minimal fat accumulation.
Are all calories the same?
While all calories provide the same amount of energy (4.184 kilojoules), the source of calories matters significantly for health, satiety, and body composition. Protein has a higher thermic effect (20-30% of calories burned during digestion) compared to carbs (5-10%) and fat (0-3%). Whole foods tend to be more satiating and nutrient-dense than processed foods. For weight management, total calories matter most, but food quality affects overall health.
How accurate are calorie calculators?
Calorie calculators provide estimates that are typically within 10-15% of actual needs. The Mifflin-St Jeor equation used in this calculator is the most accurate predictive formula available, but individual variation exists due to genetics, body composition, and metabolic differences. Use the calculator as a starting point, then track your weight over 2-4 weeks and adjust intake based on actual results.
How to Calculate Your Daily Calorie Needs
What is a Calorie Calculator?
A calorie calculator estimates the number of calories you need to consume each day to achieve your weight goals — whether that's losing weight, maintaining your current weight, or gaining weight. It takes into account your Basal Metabolic Rate (BMR), activity level, and personal goals to provide personalized daily calorie targets.
This calculator also generates a zigzag calorie cycling schedule, which varies your daily calorie intake throughout the week while keeping the same weekly total. This approach can help prevent metabolic adaptation and make dieting more sustainable.
How to Use This Calculator
- Choose your unit system (Imperial for lbs/feet or Metric for kg/cm)
- Select your gender
- Enter your age in years
- Enter your height
- Enter your current weight
- Select the activity level that best describes your weekly routine
- Choose your goal: Lose Weight, Maintain, or Gain Weight
- Click "Calculate" to see your personalized results
Formulas Used
This calculator uses the Mifflin-St Jeor equation to estimate your BMR, which is then multiplied by an activity factor to determine your maintenance calories.
Mifflin-St Jeor Equation:
- Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Activity Multipliers:
- Sedentary: ×1.2
- Lightly Active: ×1.375
- Moderately Active: ×1.55
- Very Active: ×1.725
- Extra Active: ×1.9
Calorie Adjustments:
- To lose ~0.25 kg/week: subtract 250 calories from maintenance
- To lose ~0.5 kg/week: subtract 500 calories from maintenance
- To lose ~1 kg/week: subtract 1,000 calories from maintenance
- To gain ~0.25 kg/week: add 250 calories to maintenance
- To gain ~0.5 kg/week: add 500 calories to maintenance
A deficit of approximately 7,700 calories is needed to lose 1 kg of body fat. Spreading this over a week gives roughly 1,100 cal/day, but deficits greater than 1,000 cal/day are generally not recommended without medical supervision.
Calculation Examples
Example 1: Weight Loss Goal
A 28-year-old female, 5'6" (167.6 cm), 155 lbs (70.3 kg), lightly active, wanting to lose weight:
- BMR = 10 × 70.3 + 6.25 × 167.6 − 5 × 28 − 161 = 1,410 cal/day
- Maintenance = 1,410 × 1.375 = 1,939 cal/day
- Mild loss: 1,689 cal/day | Moderate loss: 1,439 cal/day
Example 2: Weight Gain Goal
A 22-year-old male, 5'10" (177.8 cm), 150 lbs (68 kg), very active, wanting to gain weight:
- BMR = 10 × 68 + 6.25 × 177.8 − 5 × 22 + 5 = 1,676 cal/day
- Maintenance = 1,676 × 1.725 = 2,891 cal/day
- Mild gain: 3,141 cal/day | Moderate gain: 3,391 cal/day
What is Zigzag Calorie Cycling?
Zigzag calorie cycling (also called calorie shifting) is an eating approach where you vary your daily calorie intake throughout the week while keeping your weekly total the same. Instead of eating the exact same number of calories every day, you eat more on some days and less on others.
The main benefits of zigzag calorie cycling include:
- Prevents metabolic adaptation: Varying calories can help prevent your metabolism from slowing down during a calorie deficit
- Improved adherence: Higher-calorie days can make a diet feel less restrictive and more sustainable
- Aligns with activity: Eating more on workout days provides fuel when you need it most, and less on rest days
- Psychological benefit: Having higher-calorie days to look forward to can improve motivation
This calculator assigns higher calories on Monday, Wednesday, and Friday (typical workout days) and lower calories on rest days, while ensuring the weekly total matches your target.
Use Cases
- Weight Loss Planning: Determine a safe calorie deficit to lose weight steadily without extreme restriction
- Muscle Building: Calculate a calorie surplus to support muscle growth during a bulking phase
- Meal Prep: Use the zigzag schedule to plan meals for the entire week with varied portion sizes
- Plateau Breaking: If your weight loss has stalled, use calorie cycling to overcome metabolic adaptation
- Athletic Performance: Align higher calorie intake with training days and lower intake with recovery days
Tips for Effective Calorie Counting
- Use a food scale to measure portions accurately — estimating can lead to significant errors
- Track everything you eat and drink, including cooking oils, sauces, and beverages
- Do not go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision
- Focus on nutrient-dense foods rather than just calorie numbers for overall health
- Weigh yourself at the same time each day (ideally morning, after bathroom) for consistent tracking
- Adjust your calorie targets every 2-4 weeks based on actual results, since calculators provide estimates
- Stay hydrated — thirst is often confused with hunger, and water supports metabolism
- Be patient: safe, sustainable weight change is typically 0.25-0.5 kg per week