What formula does this calorie calculator use?
The Mifflin-St Jeor equation, which is widely considered the most accurate BMR formula for most adults. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: same formula minus 161. TDEE = BMR × activity multiplier.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — the minimum energy needed to keep organs functioning. TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through all physical activity. You need to eat at your TDEE to maintain your current weight.
How accurate is this calorie calculator?
The Mifflin-St Jeor equation estimates TDEE within ±10% for most adults. Accuracy decreases for athletes with very high muscle mass (formula underestimates) and individuals with medical conditions affecting metabolism. Treat results as a starting point and adjust based on real-world weight changes over 2–4 weeks.
What calorie deficit does this calculator recommend for fat loss?
After computing your TDEE, choose the weight-loss goal: a 500-calorie daily deficit targets about 1 lb (0.45 kg) per week; a 250-calorie deficit targets about 0.5 lb/week. The tool warns against dropping below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.
How many calories to gain muscle?
A surplus of 250–500 calories above TDEE combined with resistance training supports lean muscle gain. Beginners can gain muscle even at maintenance. Larger surpluses mostly add fat, not muscle, unless you are a beginner or returning to training after a long break.
What activity multiplier should I choose?
Most people underestimate their sedentary time and overestimate their active time. Honest starting points: Sedentary (1.2) if you sit most of the day with minimal exercise; Lightly active (1.375) for 1–3 workout days per week; Moderately active (1.55) for 4–5 workout days; Very active (1.725) for hard training 6–7 days; Extra active (1.9) for physical labor jobs plus daily training.
Why is my calorie count different from other calculators?
Different tools use different BMR formulas. The Mifflin-St Jeor (used here) tends to give lower, more accurate estimates for sedentary adults than the older Harris-Benedict equation. The Katch-McArdle formula (requires body fat %) is more accurate for lean athletes. All are estimates — real-world results depend on metabolic variation, food tracking accuracy, and activity consistency.
How long will it take to lose 10 lbs?
At a 500-calorie deficit: 10 lbs ÷ 1 lb/week = 10 weeks. At a 250-calorie deficit: 20 weeks. Rate slows as you lose weight because your BMR drops — recalculate your TDEE every 10 lbs lost.
Should I eat back calories burned during exercise?
If you select 'Sedentary' and entered your exercise separately, yes — eat back those calories. If your activity level already reflects your workouts (e.g. Moderately Active), do not add them back. The most common mistake is double-counting exercise.
Is this safe for children or teenagers?
The Mifflin-St Jeor formula is validated for adults 18–65. Children and teenagers have different caloric needs that account for growth. Use a pediatric-specific tool or consult a dietitian for those under 18.
Does muscle mass affect the calorie estimate?
Yes. The Mifflin-St Jeor formula uses only weight, height, age, and sex — it cannot distinguish muscle from fat. Muscular athletes will see an underestimate because muscle burns more calories than fat at rest. For lean body mass-based estimation, use the Katch-McArdle formula with a body fat percentage input.
What is the 500-calorie rule?
A 500-calorie daily deficit from your TDEE theoretically produces 1 lb (0.45 kg) of fat loss per week (since 1 lb of fat ≈ 3,500 calories). In practice, weight loss is slightly slower due to water retention changes, metabolic adaptation, and mixed tissue loss. A 250-calorie deficit is gentler and more sustainable long-term.