Calorie Calculator to Lose or Gain Weight (TDEE & BMR)
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Find the calories you need a day to maintain, lose or gain weight. Shows your TDEE and BMR in calories and kilojoules, in kilograms or pounds.
Quick answer: Daily calorie needs (TDEE) = BMR × activity factor. Using Mifflin-St Jeor, Male BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (Female: −161 instead of +5). By a common rule of thumb, a 500-calorie daily deficit below TDEE produces roughly 1 lb of fat loss per week.
Maintenance Calories (TDEE)
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calories/day to maintain current weight
ℹ️ A 500 calorie/day deficit = ~0.5 kg/week loss. Calorie needs vary; these are estimates. Consult a dietitian for personalized advice.
📐 Mifflin-St Jeor Formula
Male BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. Female: same but −161 instead of +5. TDEE = BMR × Activity factor (1.2–1.9). Example: Male, 30yrs, 75kg, 175cm, moderately active: BMR = 750+1,093.75−150+5 = 1,698.75, about 1,699 cal; TDEE = 1,698.75 × 1.55 = 2,633 cal/day.
How to Use the Calorie Calculator
Enter your age, sex, height, and weight
These four inputs feed the Mifflin-St Jeor equation, which estimates your resting calorie burn (BMR).
Select your activity level
Choose the level that reflects your typical week, not your best week. Most office workers are sedentary to lightly active even if they exercise 2–3 times per week.
Read the result for your goal
Read the row for your goal: maintenance is your TDEE, weight loss is 500 calories below it (or 250 for a gentler pace), and weight gain is 250 calories above it.
Use the result as a starting point
Track intake vs weight change over 2–3 weeks. If weight is not moving as expected, adjust your calorie target by 100–200 calories. Individual metabolic rates can differ from formula predictions by around 10%.
How Are Daily Calorie Needs Calculated?
Daily calorie needs are calculated in two steps: first your Basal Metabolic Rate (BMR) (the calories needed at complete rest), then that figure is multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE). This calculator uses the Mifflin-St Jeor equation, published in 1990 from measurements of 498 healthy adults (Mifflin et al.). A 2005 review for dietetics (Frankenfield et al.) compared four common equations and found it within 10% of measured resting metabolic rate for more people than any other, though with noteworthy errors for some individuals. For your resting figure alone, in calories and kilojoules, use the BMR calculator.
Activity Multipliers Explained
| Activity Level | Multiplier | Example |
|---|---|---|
| Sedentary | ×1.2 | Desk job, little or no exercise |
| 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 training daily |
How Many Calories to Lose Weight?
A commonly used rule of thumb is that one pound of fat contains approximately 3,500 calories. To lose 1 lb per week, create a daily deficit of 500 calories (500 × 7 = 3,500). For 2 lbs/week, a 1,000 calorie/day deficit. A commonly cited general guideline is not to go below about 1,200 calories/day (women) or 1,500 calories/day (men). This is general guidance, not medical advice, and individual needs vary, so check with a doctor or dietitian before eating that low, because very low intake risks nutritional deficiencies and muscle loss.
How Many Calories to Gain Weight or Muscle?
For slow weight gain, eat about 250 calories a day above your TDEE, which is the Weight Gain row in the results. Building muscle requires a calorie surplus, typically 200–500 calories above TDEE. Combined with adequate protein (a commonly used rule of thumb is 0.7–1g per pound of bodyweight) and progressive resistance training, a moderate surplus supports muscle growth while minimizing fat gain. A "dirty bulk" with large surpluses adds mostly fat; a "lean bulk" with 200–300 calories above TDEE is more efficient.
What is the Best Diet for Weight Loss?
Total calorie deficit is the main driver of weight loss, and the mix of protein, carbs and fat matters mainly for hunger, muscle retention and sticking with the plan. Whether you follow low-carb, low-fat, Mediterranean or intermittent fasting, adherence to a sustainable calorie deficit is the determining factor. Protein intake (a commonly used target is at least 0.7g/lb bodyweight) is important for preserving muscle during weight loss. Use our Macro Calculator to set protein, carb, and fat targets. Sleep matters here too: insufficient sleep disrupts the hormones that regulate hunger and can undermine an otherwise well-calculated deficit; see how much sleep you need for your age.
How to Calculate a Calorie Deficit for Weight Loss by Hand: Worked Example
Take a 35-year-old male, 80 kg, 178 cm. BMR = (10 × 80) + (6.25 × 178) − (5 × 35) + 5 = 800 + 1,112.5 − 175 + 5 = 1,742.5 calories. With a moderate activity multiplier of 1.55: TDEE = 1,742.5 × 1.55 = 2,701 calories/day, the estimated maintenance calorie level at current weight and activity.
Target for roughly 1 lb/week loss: by the commonly used rule of thumb, one pound of body fat represents approximately 3,500 stored calories, so a 500-calorie daily deficit (3,500 ÷ 7 days) produces roughly that rate: 2,701 − 500 = 2,201 calories/day.
Target for roughly 2 lb/week loss: 2,701 − 1,000 = 1,701 calories/day. A 1,000-calorie deficit lands just above the commonly cited 1,500-calorie general guidance for adult men and can be difficult to sustain; a 500-calorie deficit is a common, moderate starting point and a more sustainable default unless you are working directly with a healthcare provider.
Why does the "3,500 calories per pound" rule become less accurate over a long diet?
The 3,500-calorie estimate assumes a static metabolic rate, but BMR itself typically declines somewhat as body weight drops (a smaller body requires less energy), a phenomenon sometimes called metabolic adaptation. This is why weight loss often slows during an extended diet even with a consistent calorie deficit maintained on paper, and why recalculating TDEE periodically as weight changes keeps the target realistic.
Does the Source of Your Calories Matter Once the Total Is Set?
For the direction of your weight change, mostly not: the total decides it. The mix of protein, carbs and fat still affects hunger and how much muscle you keep.
Protein and the macronutrient mix
The total sets the direction of your weight change. The mix sets how the diet feels and what you keep: a deficit with too little protein tends to cost more muscle alongside the fat, which is why a calorie target is often paired with a macro breakdown (see the macro calculator).
How does muscle mass affect the calorie calculation?
Muscle tissue burns more at rest than fat, so body composition shifts the number in a way the formula cannot see, because it uses weight, height, age and sex alone. Treat the result as a starting estimate to adjust, as the FAQ below explains.
Should you eat back calories burned during exercise?
The activity multiplier in the TDEE calculation already accounts for a general activity level, so deliberately "eating back" additional calories for a workout already reflected in that multiplier can create an unintended surplus. This matters most for people using fitness trackers that separately estimate workout calories on top of an activity-adjusted TDEE: double-counting activity is a common source of stalled weight loss despite an apparently correct calorie deficit on paper.
Frequently Asked Questions
Create a calorie deficit of 500 calories/day below your TDEE for approximately 0.5 kg (1 lb) weight loss per week. This is generally considered safe and sustainable. As a rough rule of thumb, deficits larger than 750–1,000 calories/day risk muscle loss and metabolic adaptation. Commonly cited general guidance is not to go below about 1,200 cal/day (women) or 1,500 cal/day (men); that is not medical advice, so check with a doctor or dietitian first.
No. TDEE varies based on muscle mass, age, sex, hormones and metabolic efficiency. Two people of the same weight and height can have noticeably different TDEEs. The Mifflin-St Jeor formula provides a good estimate, but tracking actual intake and weight change over 2–3 weeks gives your personal TDEE.
BMR (Basal Metabolic Rate) is the calories burned at complete rest, just keeping your organs functioning. TDEE (Total Daily Energy Expenditure) includes all activity. TDEE is always higher than BMR. For a sedentary person, TDEE ≈ BMR × 1.2; for a very active person, TDEE ≈ BMR × 1.725.
Your BMR from the Mifflin-St Jeor equation is multiplied by an activity factor to get your TDEE. The full formula and a worked example are in the formula box above.
The best diet is the one you can stick to while staying in a calorie deficit. See What is the Best Diet for Weight Loss? above for how protein and the macronutrient mix fit in.
Take your TDEE and add 250 calories. For a TDEE of 2,701, that is 2,951 calories a day. Recheck after 2–3 weeks and add or cut 100–200 calories if your weight is not moving as planned. The section above covers the larger surplus used for building muscle.
Multiply calories by 4.184 to get kilojoules (kJ). A TDEE of 2,000 calories is about 8,368 kJ. The calculator shows your maintenance figure in kilojoules in the results grid, which helps if your food labels list kJ.
It gives an estimate, and most of the uncertainty comes from the activity level you pick. In the worked example above, choosing lightly active (×1.375) instead of moderately active (×1.55) lowers TDEE from 2,701 to 2,396 calories, a gap of about 300. Pick the level that matches your typical week, then adjust against your actual weight change.
Sources & Methodology
The equation and the evidence behind the page: