Calorie Calculator
Calculate your daily calorie needs based on your goals
Quick Answer
Most adults need 1,600–2,400 calories per day. Your exact number depends on age, gender, weight, and activity level.
Calorie Calculator: formula, worked examples and limitations
A complete reference answer — readable without using the calculator.
Definition
Daily calorie needs are the energy intake that produces a chosen rate of weight change, derived from Total Daily Energy Expenditure (TDEE).
What it measures
It estimates the intake target, not the weight change itself. Approximately 7,700 kcal equals 1 kg of body mass, which is where the 500 kcal/day ≈ 0.5 kg/week rule comes from.
Formula
- BMR (Mifflin-St Jeor) → TDEE = BMR × activity multiplier
- Weight loss = TDEE − 500 kcal/day
- Maintenance = TDEE
- Weight gain = TDEE + 500 kcal/day
Worked examples
Computed with the same engine as the calculator above.
Man, 30 y, 80 kg, 180 cm, moderate activity
Inputs: BMR 1780 kcal, activity ×1.55
TDEE = 2759 kcal; loss = TDEE − 500; gain = TDEE + 500
Lose 2259 · Maintain 2759 · Gain 3259 kcal/day
| Goal | Daily calories | Expected change |
|---|---|---|
| Weight loss | 2259 kcal | ≈ −0.5 kg per week |
| Maintenance | 2759 kcal | Stable weight |
| Weight gain | 3259 kcal | ≈ +0.5 kg per week |
Method
The calculator computes BMR with Mifflin-St Jeor, applies the activity multiplier to get TDEE, then adds or subtracts a fixed 500 kcal for the chosen goal.
Limitations
- Intake below about 1,500 kcal (men) or 1,200 kcal (women) is not recommended without medical supervision.
- Metabolic adaptation reduces expenditure during prolonged deficits, so targets need re-calculating after 4–6 weeks.
- Food label and portion errors of 20% are common and easily cancel a 500 kcal deficit.
Rounding rules
Calorie targets are rounded to whole calories.
Evidence level
Established basis, estimated output. The energy requirement comes from Mifflin-St Jeor; the deficit/surplus sizes follow common public-health guidance (about 0.25–1 kg per week). Individual response varies with adherence, adaptation and activity.
Sources
Method and reference values last reviewed by the SnapBodyCalc editorial team.
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Calorie Deficit Explained: The Science of Weight LossA calorie deficit is the foundation of all weight loss. Learn how to create a sustainable deficit that promotes fat loss while preserving muscle and energy.
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Frequently Asked Questions
Understanding Your Daily Calorie Needs: The Complete Guide
Calories are units of energy that fuel every function in your body — from breathing and thinking to walking and exercising. Understanding how many calories you need each day is the single most important step in any nutrition plan, whether your goal is losing weight, building muscle, or simply maintaining your current physique. Our calculator provides personalized calorie targets based on your unique body composition and lifestyle.
How Your Calorie Targets Are Calculated
We use the Mifflin-St Jeor equation, recognized by the American Dietetic Association as the most accurate BMR prediction formula for healthy individuals. First, your Basal Metabolic Rate (BMR) is calculated using your age, weight, height, and sex. Then, we multiply by an activity factor to estimate your Total Daily Energy Expenditure (TDEE). Finally, we apply goal-specific adjustments: approximately −500 calories for weight loss (targeting ~0.5 kg per week), your TDEE for maintenance, or +300–500 for lean muscle gain.
Calorie Deficit: The Foundation of Weight Loss
A calorie deficit occurs when you consume fewer calories than your body burns. A deficit of 500 calories per day typically results in approximately 0.5 kg of fat loss per week, since 1 kg of body fat contains roughly 7,700 calories. However, creating too large a deficit (eating below your BMR) can backfire — causing metabolic slowdown, muscle loss, increased hunger hormones, and nutrient deficiencies. A moderate deficit of 300–500 calories below TDEE is the sweet spot for sustainable fat loss.
Calorie Surplus for Muscle Building
Building muscle requires extra energy. A controlled surplus of 200–500 calories above your TDEE, combined with progressive resistance training and adequate protein (1.6–2.2 g/kg), provides the building blocks for muscle growth while minimizing fat gain. This approach, known as "lean bulking," is more effective than excessive surpluses that primarily add body fat. Use our Protein Calculator to optimize your protein intake during a surplus.
Activity Level: Getting It Right
Choosing the correct activity level is crucial for accurate results. Most people overestimate their activity level, leading to calorie targets that are too high. "Sedentary" applies if you have a desk job and get minimal exercise. "Lightly active" means you walk regularly or exercise 1–3 times per week. "Moderately active" describes consistent exercise 3–5 days per week. "Very active" is reserved for intense daily exercise or physical labor. When in doubt, select a lower activity level and adjust based on real-world results over 2–3 weeks.
Why Your Calorie Needs Change Over Time
Your calorie requirements aren't static. They change as your weight changes (lighter bodies burn fewer calories), as you age (metabolic rate decreases by about 1–2% per decade after age 20), and as your activity patterns shift. During a prolonged deficit, your body undergoes metabolic adaptation — becoming slightly more efficient and burning fewer calories. This is why periodic "diet breaks" at maintenance calories can help overcome weight loss plateaus.
Tracking and Adjusting Your Intake
After calculating your target, track your intake for 2–3 weeks and monitor your weight trend. If you're not seeing expected results, adjust by 100–200 calories. Weigh yourself at the same time daily (ideally morning, after bathroom, before eating) and average the weekly results to account for normal daily fluctuations of 0.5–2 kg from water, food volume, and sodium intake.
Beyond Calories: The Quality Factor
While calorie quantity determines weight change, calorie quality affects body composition, energy, and long-term health. A 2,000-calorie diet of whole foods (lean proteins, vegetables, whole grains, healthy fats) produces dramatically different health outcomes than 2,000 calories of processed foods. Once you know your calorie target, use our Macro Calculator to break it into optimal protein, carbohydrate, and fat ratios for your goal.
Calorie Needs for Special Populations
Pregnant and breastfeeding women need approximately 300–500 additional calories per day. Teenagers and growing adolescents should avoid restrictive diets and focus on nutrient density. Adults over 60 may benefit from slightly higher protein despite lower overall calorie needs. Athletes with high training volumes may need 3,000–5,000+ calories depending on sport, body size, and training phase.
Your Inputs Stay in Your Browser
All calculations happen entirely in your browser — your age, weight, height, and calorie targets are never sent to any server or stored anywhere. SnapBodyCalc is built with privacy as a core principle. Analytics and web fonts still make standard requests that include your IP address and the page URL — but never your measurements.