Calorie Calculator
Calculate your daily calorie needs using the scientifically validated Mifflin-St Jeor formula. Enter your age, sex, weight, height, and activity level to get your BMR (basal metabolic rate), TDEE (total daily energy expenditure), and calorie targets for weight loss, maintenance, and gain.
All calculations use standard published formulas. Results are for informational use only.
Unit system
Sex
Activity level
How to use this calorie calculator
- Select your unit system and sex.
- Enter your age, weight, and height.
- Choose the activity level that best describes your typical week.
- Your BMR, maintenance TDEE, weight loss, and weight gain targets appear instantly.
- Use the step-by-step section to see exactly how each number was calculated.
- Adjust your intake by no more than 500 kcal from maintenance in either direction for safe, sustainable results.
The calorie formula -- how daily energy needs are calculated
Step 1: Basal Metabolic Rate (BMR)
BMR is the number of calories your body needs to sustain vital functions at complete rest -- breathing, circulation, cell repair, and temperature regulation. This calculator uses the Mifflin-St Jeor equation, the most accurate widely available BMR formula:
Step 2: Activity multiplier (TDEE)
To get TDEE, multiply your BMR by the activity factor that reflects your typical weekly exercise:
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise | 1.2 |
| Lightly active | 1-3 days of exercise per week | 1.375 |
| Moderately active | 3-5 days of exercise per week | 1.55 |
| Very active | Hard exercise 6-7 days per week | 1.725 |
| Extra active | Physical job or twice-daily training | 1.9 |
Step 3: Goal adjustments
One pound (0.45 kg) of fat stores roughly 3,500 calories. A consistent daily deficit or surplus of 500 calories creates a weekly change of approximately 0.5 kg:
What is TDEE and why does it matter?
Total Daily Energy Expenditure (TDEE) is the total number of calories your body uses in a day. It is the sum of four components: Basal Metabolic Rate (the largest share, typically 60-75% of TDEE), the Thermic Effect of Food (energy used to digest and absorb food, roughly 10%), Non-Exercise Activity Thermogenesis (NEAT -- fidgeting, standing, walking around daily life), and deliberate exercise.
Most people know roughly how much they exercise per week but significantly underestimate NEAT. NEAT can account for a 500-1,000 calorie-per-day difference between two people of the same size who do the same structured workouts, if one sits all day and the other moves around actively. This is one reason activity multipliers have such a large effect on TDEE.
Understanding your TDEE changes how you think about nutrition. Instead of following a fixed calorie number from an app or a magazine, you have a personalised starting point based on your actual body size and activity level. From there, a small, consistent adjustment -- rather than extreme restriction or overfeeding -- is all you need to move toward any weight goal.
TDEE is not fixed. It changes as your weight, age, and activity level change. Losing 10 kg reduces both BMR (you are carrying less mass) and potentially NEAT (lighter body, less effort). Recalculating every 4-8 weeks when actively managing weight keeps your targets accurate.
Understanding your calorie results
BMR -- your biological floor
BMR is how many calories your body burns at complete rest over 24 hours. Think of it as the minimum your body needs just to stay alive -- before any movement at all. Eating significantly below your BMR for extended periods causes metabolic adaptation, muscle loss, and hormonal disruption. Sensible calorie targets never drop below BMR.
TDEE -- your maintenance level
Eat consistently at your TDEE and your weight should hold steady. This assumes your activity level and body composition remain roughly constant. Most people are surprised by how high their maintenance calories are -- TDEE for a moderately active adult is often 2,000-2,800 kcal. This is the target for weight maintenance.
Weight loss -- the 500-calorie deficit
A 500 kcal daily deficit below TDEE produces approximately 0.5 kg (1 lb) of fat loss per week. This is the conservative, evidence-backed approach. More aggressive deficits accelerate the scale but also increase muscle loss, hunger, fatigue, and the risk of nutrient deficiency. For most people, 500 kcal under TDEE is the sweet spot between meaningful progress and sustainability.
Weight gain -- eating above TDEE
Adding 500 kcal per day above TDEE supports a weight gain of roughly 0.5 kg per week. Not all gained weight will be muscle -- without resistance training, a significant portion will be fat. If muscle gain is the goal, pair the caloric surplus with a consistent lifting programme and adequate protein (1.6-2.2 g per kg body weight per day).
Calorie calculation examples
Example 1 -- 35-year-old male, moderately active
Weight: 80 kg, Height: 178 cm, Age: 35, Moderately active (3-5 days/week)
- BMR = (10 x 80) + (6.25 x 178) - (5 x 35) + 5 = 800 + 1112.5 - 175 + 5 = 1,742.5 kcal
- TDEE = 1,742.5 x 1.55 = 2,701 kcal/day
- Weight loss target: 2,701 - 500 = 2,201 kcal/day
Example 2 -- 28-year-old female, lightly active
Weight: 63 kg, Height: 165 cm, Age: 28, Lightly active (1-3 days/week)
- BMR = (10 x 63) + (6.25 x 165) - (5 x 28) - 161 = 630 + 1031.25 - 140 - 161 = 1,360.25 kcal
- TDEE = 1,360.25 x 1.375 = 1,870 kcal/day
- Weight loss target: 1,870 - 500 = 1,370 kcal/day
Example 3 -- Imperial inputs
Weight: 180 lbs, Height: 6 ft 0 in, Age: 42, Male, Very active
- Convert: 180 lbs = 81.6 kg, 72 inches = 182.9 cm
- BMR = (10 x 81.6) + (6.25 x 182.9) - (5 x 42) + 5 = 816 + 1143.1 - 210 + 5 = 1,754 kcal
- TDEE = 1,754 x 1.725 = 3,026 kcal/day
Quick tips for hitting your calorie targets
- Weigh yourself consistently: Same time, same conditions (morning, after toilet, before eating). Average across a week to see the real trend.
- Recalculate every 4-6 weeks: As your weight changes, so does your TDEE. Recalculate to keep your target accurate.
- Protein is key: Aim for 1.6-2.2 g of protein per kg body weight to preserve muscle during a calorie deficit.
- Activity level underestimation: Most people overestimate their activity. If weight is not changing as expected, drop one activity level and reassess.
- Do not go below BMR: Very low calorie diets trigger metabolic adaptation and muscle breakdown. Stay above your BMR in all scenarios except medically supervised protocols.
- Liquid calories count: Juice, alcohol, and high-calorie coffee drinks are frequent reasons calorie budgets are exceeded without noticing.
Common calorie calculation mistakes
Overestimating activity level
Selecting "Very active" when you exercise 3 days a week overstates your TDEE by several hundred calories. Consistent overestimation is the most common reason people do not lose weight despite "eating at a deficit." Be conservative with your activity level and adjust upward if the results do not match expectations after 2-3 weeks of tracking.
Ignoring tracking consistency
A TDEE estimate is only useful if you track calories accurately. Research shows most people underestimate their food intake by 20-40%. Weighing food (rather than estimating portions) for at least the first few weeks gives a far more accurate picture and helps calibrate future estimates.
Treating the formula as exact
The Mifflin-St Jeor formula is the most accurate predictive equation available for general use, but it is still a statistical estimate. People with unusually high or low muscle mass, thyroid conditions, or significant hormonal differences can deviate meaningfully from the prediction. Use the calculator as a starting point and let your real-world weight trend adjust your targets.
Setting too large a deficit
A 1,000 kcal/day deficit sounds twice as good as 500 kcal, but in practice it increases hunger, reduces training performance, accelerates muscle loss, and is harder to sustain. Meta-analyses consistently show that moderate deficits (400-600 kcal/day) produce comparable long-term fat loss to aggressive deficits while preserving more muscle and being far easier to maintain.
Frequently Asked Questions
What is a calorie calculator and what does TDEE mean?
A calorie calculator estimates your Total Daily Energy Expenditure (TDEE) -- the number of calories your body burns in a day when you factor in your activity level. TDEE is made up of two components: your Basal Metabolic Rate (BMR), which is the energy your body needs at complete rest just to sustain vital functions, and the energy burned through movement and exercise. Knowing your TDEE lets you set an accurate calorie target for weight maintenance, loss, or gain.
What is the Mifflin-St Jeor formula?
The Mifflin-St Jeor equation is the formula this calculator uses to estimate BMR. Published in 1990, it is considered the most accurate BMR formula for most people compared to older alternatives like the Harris-Benedict equation. For men: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5. For women: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) - 161. Multiple validation studies have found it produces results within 10% of measured expenditure for most healthy adults.
How many calories should I eat to lose weight?
To lose approximately 0.5 kg (1 lb) per week, eat roughly 500 calories per day below your maintenance TDEE. This creates a 3,500-calorie weekly deficit, which corresponds to about 0.5 kg of fat. For most adults, this means consuming no fewer than 1,200-1,500 calories per day -- going lower than this risks nutritional deficiency and muscle loss. Sustainable weight loss is a gradual process: a deficit of 500 cal/day is generally considered safe and effective.
How many calories do I need to maintain my weight?
Your maintenance calorie level is your TDEE -- the number shown as the main result in this calculator. If you consistently eat at this level, your weight should remain stable. This assumes your activity level stays constant. Any significant change in exercise habits, age, or body composition will shift your TDEE over time, so recalculating every few months is useful.
How accurate is this calorie calculator?
The Mifflin-St Jeor formula estimates BMR within about 10% for most healthy adults. The activity multiplier introduces additional variability because self-reported exercise levels are often inaccurate. For most people, the TDEE estimate will be within 5-15% of actual expenditure. Use the result as a starting point, track your weight for 2-3 weeks, then adjust intake by 100-200 calories if not seeing the expected change.
Does sex affect calorie needs?
Yes -- men generally have higher calorie needs than women of the same height, weight, and age, primarily because men typically carry more skeletal muscle mass. The Mifflin-St Jeor formula applies a sexdifference through the constant at the end: +5 for men and -161 for women. At the same weight and height, a man's BMR will be approximately 166 calories per day higher than a woman's.