Calorie Calculator: How Many Calories Do You Need?
A 30-year-old male, 5'9", 170 lbs with light activity needs approximately 2,367 calories per day to maintain weight. For weight loss of 1 lb/week, target 1,867 calories. For lean muscle gain, target 2,667 calories. Based on the Mifflin-St Jeor equation.
Calculate Your Daily Calories
Enter your stats for a personalized calorie target.
Your Daily Calories
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calories/day
Understanding Daily Calorie Needs
Your daily calorie needs are determined by two factors: your Basal Metabolic Rate (BMR) and your activity level. BMR accounts for 60-75% of total daily calories — it is the energy your body uses just to stay alive. The remaining 25-40% comes from physical activity and the thermic effect of food (calories burned during digestion).
Calorie Targets by Goal
| Goal | Calorie Adjustment | Expected Rate | |||||
|---|---|---|---|---|---|---|---|
| Aggressive fat loss | -1,000 cal/day | ~2 lbs/week | |||||
| Moderate fat loss | -500 cal/day | ~1 lb/week | |||||
| Mild fat loss | -250 cal/day | ~0.5 lb/week | |||||
| Maintenance | 0 | Weight stable | |||||
| Lean bulk | +250 cal/day | ~0.5 lb/week gain | |||||
| Muscle building | +500 cal/day | ~1 lb/week gain | Macronutrient BreakdownCalories alone do not tell the whole story. How you distribute those calories across protein, carbohydrates, and fat affects body composition, energy levels, and satiety. | Diet Style | Protein | Carbs | Fat |
| Balanced | 30% | 40% | 30% | ||||
| Low Carb | 40% | 20% | 40% | ||||
| High Protein | 40% | 35% | 25% | ||||
| Keto | 30% | 5% | 65% |
For fat loss, prioritize protein at 0.7-1.0 g per pound of body weight to preserve muscle mass during a deficit.
1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. doi:10.1093/ajcn/51.2.241
2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc. 2005;105(5):775-789. doi:10.1016/j.jada.2005.02.005
3. U.S. Department of Agriculture. Dietary Guidelines for Americans, 2020-2025. USDA. https://www.dietaryguidelines.gov/
Frequently Asked Questions
How many calories should I eat to lose weight?
To lose weight, eat 300-500 fewer calories than your Total Daily Energy Expenditure (TDEE). This creates a caloric deficit that forces your body to use stored fat for energy. A 500-calorie deficit produces approximately 1 pound of fat loss per week. Use the calculator above to find your TDEE, then subtract accordingly.
What is a calorie deficit?
A calorie deficit occurs when you consume fewer calories than your body burns. Your body makes up the difference by burning stored energy (primarily body fat). A deficit of 3,500 calories roughly equals 1 pound of fat loss, though individual results vary based on metabolic adaptation and body composition.
How accurate is this calorie calculator?
The Mifflin-St Jeor equation is accurate to within 10% for most healthy adults. Factors like genetics, medications, hormonal conditions (thyroid disorders, PCOS), and body composition can affect accuracy. Use your calculated number as a starting point and adjust based on actual weight trends over 2-3 weeks.
Should I eat back exercise calories?
Generally, no. The activity multiplier in this calculator already accounts for your exercise. If you separately track exercise calories (via a fitness tracker) and add them back, you risk double-counting. Exception: if you have a single unusually intense workout (marathon, all-day hike), eating back 50% of those extra calories is reasonable.
How many calories is too few?
The American College of Sports Medicine recommends women eat no fewer than 1,200 calories/day and men no fewer than 1,500 calories/day without medical supervision. Very low calorie diets (VLCDs below 800 calories) should only be done under a doctor's care. Eating too little causes muscle loss, nutrient deficiencies, metabolic slowdown, and hormonal disruption.
Does metabolism slow with age?
Yes, but less than commonly believed. A 2021 study in Science found that metabolism remains relatively stable from age 20 to 60, declining only about 0.7% per year. The bigger factor is usually decreased muscle mass and activity level with age, both of which are modifiable through strength training and staying active.
Calories vs macros — what matters more for weight loss?
For weight loss specifically, total calories matter most. You cannot lose weight without a calorie deficit regardless of macro ratios. However, macro distribution affects body composition — higher protein intake (0.7-1g per pound) preserves muscle during a deficit, and adequate fat (minimum 20% of calories) supports hormonal health.
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