Calorie Calculator

How Daily Calorie Needs Are Calculated

The Two-Step Process

Calculating your daily calorie needs involves two steps: first calculating your Basal Metabolic Rate (BMR), then multiplying by your activity level. Your BMR is the calories you burn at rest just to keep your body functioning—breathing, heart beating, cells regenerating.

BMR Formula (Mifflin-St Jeor Equation)

This is the most accurate formula for modern populations, developed in 1990:

For Men:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

For Women:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

TDEE (Total Daily Energy Expenditure) = BMR × Activity Multiplier

Step-by-Step Example

Let's calculate for a 35-year-old woman, 5'6" (168 cm), 150 lbs (68 kg), moderately active:

Calculate BMR: (10 × 68) + (6.25 × 168) - (5 × 35) - 161
Do the math: 680 + 1,050 - 175 - 161 = 1,394 calories/day at rest
Apply activity multiplier: Moderately active = 1.55
Calculate TDEE: 1,394 × 1.55 = 2,161 calories/day
Result: She needs about 2,160 calories/day to maintain current weight

Activity Level Multipliers

Sedentary (1.2): Desk job, little to no exercise (most people overestimate their activity)
Lightly Active (1.375): Light exercise 1-3 days/week
Moderately Active (1.55): Moderate exercise 3-5 days/week
Very Active (1.725): Hard exercise 6-7 days/week
Extremely Active (1.9): Physical job + hard exercise daily, or athlete training twice per day

How to Use This Calculator

Enter your age: Your metabolic rate decreases about 2% per decade after age 20
Select biological sex: Men have higher BMR due to typically higher muscle mass
Enter your weight: Use current weight in pounds or kilograms
Enter your height: Be accurate—height significantly affects calorie needs
Select activity level: Be honest. Most people are sedentary or lightly active, not moderate
Choose your goal: Maintain weight, lose weight, or gain weight
Click Calculate: See your maintenance calories and target for your goal

Understanding Your Results

Maintenance Calories

This is the number of calories you need to eat daily to maintain your current weight. If you eat this amount consistently, your weight shouldn't change. This is your TDEE (Total Daily Energy Expenditure). Most adults have maintenance calories between 1,600-2,800 depending on size, sex, age, and activity.

Weight Loss Calories

To lose 1 pound per week (recommended safe pace), you need a 500-calorie daily deficit (1 lb of fat = 3,500 calories ÷ 7 days = 500/day). For the woman in our example (2,160 maintenance), weight loss target would be 1,660 calories/day. Faster weight loss (1.5-2 lbs/week) requires 750-1,000 calorie deficit but shouldn't go below 1,200 calories/day for women or 1,500 for men without medical supervision.

Weight Gain Calories

To gain 0.5-1 pound per week (healthy pace for muscle building), add 250-500 calories to your maintenance. For our example, weight gain target would be 2,410-2,660 calories/day. Combined with strength training, this supports muscle growth with minimal fat gain. Gaining faster (2+ lbs/week) usually means excessive fat gain.

Calorie Goals for Different Objectives

Fat Loss (Preserving Muscle)

500 calorie deficit per day (1 lb/week loss)
Protein: 0.7-1g per lb of body weight
Strength train 3-4x per week to maintain muscle
Eat most carbs around workouts
Don't go below 1,200 (women) or 1,500 (men) calories

Muscle Gain (Lean Bulk)

250-500 calorie surplus per day (0.5-1 lb/week gain)
Protein: 0.8-1g per lb of body weight
Progressive strength training 4-5x per week
Emphasize whole foods, sufficient carbs for energy
Track strength progression, not just scale weight

Athletic Performance

At maintenance or slight surplus (don't diet during season)
Carbs: 45-65% of calories for energy
Protein: 0.5-0.8g per lb (higher for strength athletes)
Time meals around training for optimal performance
Prioritize recovery and sleep

Common Mistakes That Sabotage Calorie Counting

1. Overestimating Activity Level

Most people think they're more active than they are. Working out 3x per week but sitting 8-10 hours daily makes you "lightly active," not "moderately active." Overestimating activity by one level adds 200-400 unnecessary calories, preventing weight loss. When in doubt, choose the lower activity level.

2. Not Tracking Liquid Calories

A large latte (320 cal), orange juice (220 cal), and soda (150 cal) = 690 calories without eating anything. Alcohol is particularly sneaky: a single IPA beer has 200-300 calories. Switch to water, black coffee, or unsweetened tea to save 300-700 calories daily without feeling deprived.

3. Weekend Calorie Amnesia

You track perfectly Monday-Friday (1,600 cal/day = 8,000 total), then eat 3,000 calories Saturday and Sunday (6,000 total). Weekly total: 14,000 calories (2,000/day average), which is maintenance, not a deficit. You can't out-discipline a weekend of overeating. Track weekends or practice moderation.

4. Eating Back All Exercise Calories

Fitness trackers overestimate calories burned by 20-50%. If your watch says you burned 400 calories running, you actually burned 250-320. Eating back all 400 creates a surplus instead of a deficit. Eat back only 50% of exercise calories if weight loss is your goal.

5. Not Adjusting as You Lose Weight

A 200-lb person burns more calories than a 170-lb person doing the same activities. As you lose weight, your calorie needs decrease. Recalculate your targets every 10-15 lbs lost. This is why weight loss slows over time—you need to keep adjusting downward.

Frequently Asked Questions

How accurate are calorie calculators?

Calorie calculators provide estimates within 10-20% accuracy for most people. Individual variation exists due to genetics, muscle mass, metabolic adaptation, and hormones. Use the calculator's result as a starting point, then adjust based on real-world results after 2-3 weeks. If you're not losing weight at the suggested deficit, reduce by another 100-200 calories. If losing too fast (over 2 lbs/week), add 100-200 calories.

Is 1,200 calories enough to lose weight?

1,200 calories is the minimum recommended for women (1,500 for men) without medical supervision. For small, sedentary women (5'0"-5'3", 110-130 lbs), 1,200 may be appropriate for weight loss. For average or tall women, active individuals, or men, 1,200 is too low—it risks nutrient deficiencies, muscle loss, metabolic slowdown, and extreme hunger that leads to bingeing. Most people lose weight successfully on 1,400-1,800 calories (women) or 1,800-2,200 (men).

Do I need to count calories to lose weight?

No, but it's the most reliable method. Alternatives include portion control (half your plate vegetables, quarter protein, quarter carbs), intuitive eating (eat when hungry, stop when satisfied), or macro tracking. However, studies show people who track calories lose 2x more weight than those who don't. You can start without counting and add tracking if you plateau. Even tracking for 2-4 weeks educates you about portion sizes.

Should I eat the same calories every day?

No, your calorie target is a weekly average. You can eat 1,500 Monday-Friday (7,500 total) and 2,000 Saturday-Sunday (4,000 total) for a weekly total of 11,500 (1,643/day average). This "calorie cycling" can make dieting more sustainable psychologically while still creating the necessary deficit. What matters is weekly total, not hitting the exact number daily.

Why am I not losing weight at a calorie deficit?

Common reasons: underestimating food intake (not weighing food, forgetting snacks/drinks), overestimating activity/exercise burn, not giving it enough time (weight fluctuates 2-5 lbs daily due to water, need 2-3 weeks to see trends), medical issues (thyroid, PCOS, medications that affect metabolism), or metabolic adaptation (body reduces calorie burn after prolonged dieting). Solution: track more accurately, be patient, recalculate if needed, or consult a doctor if stalled for 4+ weeks despite compliance.

Can I eat whatever I want as long as I stay under my calorie limit?

Technically yes for weight loss—a calorie is a calorie thermodynamically. But for health, energy, satiety, and muscle preservation, food quality matters enormously. 1,500 calories of vegetables, lean protein, and whole grains keeps you full, energized, and provides nutrients. 1,500 calories of candy and chips leaves you hungry, tired, and nutrient-deficient. Use the 80/20 rule: 80% whole, nutritious foods, 20% treats and flexibility.

Disclaimer: This calculator provides estimates for educational purposes only. Individual calorie needs vary based on genetics, hormones, medications, and other factors not accounted for in standard formulas. Results should not be considered medical advice. Consult with a registered dietitian or physician before starting any diet, especially if you have medical conditions or are taking medications that affect metabolism.