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How Many Calories Do You Need Per Day?
Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period. It accounts for your Basal Metabolic Rate (BMR) — the energy your body uses at complete rest — plus the calories burned through physical activity, the thermic effect of food (digesting what you eat), and non-exercise activity thermogenesis (fidgeting, walking, standing).
Understanding your TDEE is the foundation of any nutrition strategy. To lose weight, you need to consume fewer calories than your TDEE. To gain weight or build muscle, you need to consume more. To maintain your current weight, you match your intake to your TDEE. Our calculator estimates your personal TDEE based on your age, sex, height, weight, and activity level.
Quick reference: A moderately active 30-year-old male at 5'10" and 175 lbs has an estimated TDEE of approximately 2,650 calories/day. A moderately active 30-year-old female at 5'5" and 140 lbs has an estimated TDEE of approximately 2,050 calories/day.
How Our Calculator Works
We use the Mifflin-St Jeor equation, which research has shown to be the most accurate predictive equation for estimating BMR in most populations. The formula calculates your Basal Metabolic Rate, then multiplies it by an activity factor to estimate your TDEE.
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
The activity multiplier ranges from 1.2 (sedentary — desk job, little exercise) to 1.9 (extremely active — physical job plus intense daily training). Most people overestimate their activity level. If you work a desk job and exercise 3–4 times per week, "lightly active" (1.375) or "moderately active" (1.55) is typically most accurate.
The result is an estimate. Individual metabolism varies by 5–15% due to genetics, body composition, hormonal factors, and metabolic adaptation. Use your TDEE as a starting point, then adjust based on real-world results over 2–4 weeks.
Calorie Targets for Different Goals
Weight loss: A deficit of 500 calories below your TDEE produces approximately 1 lb of weight loss per week. A 750-calorie deficit targets about 1.5 lbs/week. Deficits beyond 1,000 calories daily are generally not recommended — they increase muscle loss, lower metabolic rate, and are difficult to sustain. For most people, a 500-calorie deficit provides a sustainable pace.
Muscle gain (bulking): A surplus of 250–500 calories above your TDEE supports muscle growth when combined with resistance training. Larger surpluses don't accelerate muscle growth — they just increase fat gain. Beginners can build muscle effectively at a 300-calorie surplus, while experienced lifters may need only 200–300 above TDEE.
Maintenance: Match your calorie intake to your TDEE. This is useful for body recomposition (building muscle while losing fat, which happens slowly at maintenance calories with adequate protein and progressive resistance training) or for maintaining results after a cut or bulk phase.
Reverse dieting: After an extended calorie deficit, gradually increasing calories by 50–100 per week back toward your TDEE helps restore metabolic rate without rapid fat regain. This approach is particularly important after prolonged dieting.
Why Your TDEE Changes Over Time
Your TDEE is not a fixed number — it shifts in response to changes in your body and behavior. Metabolic adaptation is the most significant factor: when you eat in a deficit, your body gradually reduces energy expenditure through lower non-exercise activity, reduced thermic effect of food, and hormonal changes. Studies show metabolic adaptation can reduce TDEE by 5–15% below what equations predict after extended dieting.
Age reduces BMR by approximately 1–2% per decade after age 20, primarily due to loss of muscle mass. This is why the same diet that maintained your weight at 25 may cause gradual gain at 45.
Body composition matters: muscle tissue burns approximately 6 calories per pound per day at rest, while fat tissue burns roughly 2 calories per pound. Adding 10 lbs of muscle raises your resting metabolic rate by approximately 40 calories/day — meaningful over time but not the metabolic miracle sometimes claimed.
Hormonal factors including thyroid function, cortisol levels, and sex hormones influence metabolic rate. Conditions like hypothyroidism can reduce BMR by 10–20%. If your weight loss stalls despite accurate tracking, hormonal testing may be warranted.
Common Calorie Counting Mistakes
Underestimating portions is the most common error. Research consistently shows that people underestimate calorie intake by 20–50%. Using a food scale for at least 2 weeks — even if you don't continue long-term — calibrates your visual portion estimates and dramatically improves accuracy.
Ignoring liquid calories from coffee drinks, smoothies, juice, alcohol, and soda can add 300–800 calories/day. A large latte with flavored syrup is 300+ calories. Two glasses of wine add 250+ calories. These add up quickly.
Overestimating exercise calories is nearly universal. Fitness trackers and cardio machines typically overestimate calorie burn by 20–40%. A 30-minute jog might display 400 calories burned, but the actual additional expenditure (above what you'd burn at rest) is closer to 250. Don't "eat back" all your exercise calories.
Weekend inconsistency derails many plans. Five days at a 500-calorie deficit (2,500 calories saved) followed by two weekend days at a 1,000-calorie surplus (2,000 calories added) leaves you with only a net 500-calorie weekly deficit — one-seventh of what you'd expect.
Not adjusting over time. As you lose weight, your TDEE decreases because you're moving a smaller body. Recalculate every 10–15 lbs lost, or every 4–6 weeks, to ensure your deficit remains appropriate.
TDEE vs. BMR: What's the Difference?
Your BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — lying in bed, awake, in a temperature-neutral environment, having fasted for 12 hours. It represents the energy required for basic physiological functions: breathing, circulation, cell production, nutrient processing, and brain function. BMR typically accounts for 60–75% of your TDEE.
Your TDEE (Total Daily Energy Expenditure) includes your BMR plus all additional energy expenditure: physical activity (15–30% of TDEE), the thermic effect of food (approximately 10% of calorie intake), and non-exercise activity thermogenesis or NEAT (varies widely — can be 200–900 calories/day depending on your job and habits).
Why this matters: You should never eat below your BMR for extended periods. Doing so can trigger significant metabolic adaptation, muscle loss, hormonal disruption, and nutrient deficiencies. A safe calorie floor is generally your BMR or 1,200 calories for women and 1,500 for men — whichever is higher.
Frequently Asked Questions
To lose approximately 1 lb per week, eat 500 calories below your TDEE. For a moderately active person with a TDEE of 2,400, that means eating 1,900 calories/day. Don't go below your BMR or below 1,200 calories (women) / 1,500 calories (men) without medical supervision. Sustainable weight loss is 0.5–1% of body weight per week.
The Mifflin-St Jeor equation is considered the most accurate for most adults, as confirmed by the Academy of Nutrition and Dietetics. It's more accurate than the older Harris-Benedict equation, particularly for overweight and obese individuals. However, no formula is perfectly accurate — use results as a starting point and adjust based on real-world results.
Your sedentary TDEE (no exercise) is your BMR multiplied by 1.2. This accounts for basic daily movement — walking around your home, cooking, light activities. For a person with a BMR of 1,600, sedentary TDEE is approximately 1,920 calories/day. Add exercise calories on top of this as needed.
Generally, no — or at most, eat back half. Calorie burn estimates from fitness trackers and gym machines are typically inflated by 20–40%. If your tracker says you burned 500 calories running, the actual additional expenditure above your baseline is likely 300–350. Eating back all reported exercise calories often eliminates your deficit entirely.
The most common reasons are inaccurate calorie tracking (underestimating intake or overestimating expenditure), metabolic adaptation from prolonged dieting, water retention masking fat loss (especially in the first 2–3 weeks of a new diet or exercise program), and weekend overconsumption offsetting weekday deficits. Try using a food scale for one week to verify your actual intake.
When eating in a calorie deficit, higher protein intake helps preserve muscle mass. Research supports consuming 0.7–1.0 grams of protein per pound of body weight during a cut. For a 170 lb person, that's 120–170 grams of protein daily. This also increases satiety, making the deficit easier to sustain.
The thermic effect of food (TEF) is the energy your body uses to digest, absorb, and metabolize what you eat. It accounts for approximately 10% of your total calorie intake. Protein has the highest TEF (20–30% of calories consumed), followed by carbohydrates (5–10%) and fats (0–3%). This is one reason high-protein diets can support weight loss — more energy is spent processing the food itself.
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