Maintain weight
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Calorie Calculator
See how many calories you burn in a day based on your BMR and activity level. Essential for weight loss, weight gain, or maintaining your current weight.
Daily calorie targets
Lose 0.5 kg/wk
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Gain 0.5 kg/wk
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kcal/day
How your calorie target is set
Every calorie calculator starts with the same foundation: your Basal Metabolic Rate (BMR) — the calories your body burns simply by being alive, with no physical activity whatsoever. This is the energy your organs need, your lungs need to breathe, your heart needs to pump blood, and your brain needs to think. Even in complete bed rest, you burn this many calories. BMR accounts for roughly 60–75% of your total daily energy expenditure, with physical activity and digestion making up the rest.
The calculator above uses the Mifflin-St Jeor equation, which was developed in 1990 and is considered the most accurate BMR formula for most adults. For a 30-year-old male at 70 kg and 175 cm: BMR = (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 1,666 kcal/day. For a 30-year-old female at the same weight and height: BMR = (10 × 70) + (6.25 × 175) − (5 × 30) − 161 = 1,505 kcal/day. The sex difference in this formula is primarily driven by differences in average body composition — specifically, men on average carry more muscle mass, which burns more calories at rest than fat.
BMR is multiplied by an activity factor to give your Total Daily Energy Expenditure (TDEE). A sedentary person (desk job, little exercise) multiplies by 1.2. A moderately active person (exercise 3–5 days per week) multiplies by 1.55. A very active person (intense exercise 6–7 days per week) multiplies by 1.725. These multipliers are population averages and can be off by ±20% for individuals, which is why calorie calculations are estimates — your actual energy needs depend on factors like muscle mass, thyroid function, genetics, and even ambient temperature.
Understanding deficit, maintenance, and surplus
Your maintenance calories are simply your TDEE — the calories that would maintain your current weight. Eating above this is a surplus, eating below is a deficit. A deficit of approximately 3,500 kcal equals 1 pound (0.45 kg) of body fat, because a pound of body fat stores approximately 3,500 kcal of energy. To lose 1 lb per week, you need a daily deficit of 500 kcal — either by eating 500 kcal less, burning 500 kcal more through exercise, or some combination of both. At 2 lb per week, the deficit is 1,000 kcal/day, which is aggressive and typically only sustainable for short periods under professional supervision.
Fat loss and muscle gain cannot happen at the same time in any meaningful way — they are physiologically opposite processes. When you are in a deficit, your body must source energy from its own stores, which includes body fat but also some muscle protein if protein intake is insufficient. This is why adequate protein intake (1.6–2.2 g per kg of body weight per day) during a deficit is critical: it signals your body to preserve muscle mass. When you are in a surplus with resistance training, your body uses the extra energy to build muscle protein. Eating extra protein beyond what your muscles can use for repair does not build more muscle — it is simply stored as fat.
Why tracking calories is harder than it sounds
The calorie numbers on food labels can be off by up to 20% in either direction under FDA regulations. A packet labeled 200 kcal might actually contain anywhere from 160 to 240 kcal. This is not fraud — it is legal tolerance for natural variation in ingredient density and moisture content. Restaurant dishes are typically even more variable, because portion sizes in restaurants bear little relation to what you ordered. A "calorie" in food labeling refers to a kilocalorie (kcal) — the energy needed to raise 1 kg of water by 1°C. In nutrition, the terms calorie and kilocalorie are used interchangeably, which creates confusion when comparing different countries' food databases.
Additionally, the calories your body absorbs from protein, fat, carbohydrates, and alcohol are not equal. Protein has a thermic effect of approximately 20–30% — your body spends 20–30% of the calories in protein processing it. This means 100 kcal of protein effectively yields 70–80 kcal of net energy. Fat has a thermic effect of 0–3%, and carbohydrates 5–10%. This is another reason calorie counts are approximations — the net caloric value of food depends on its macronutrient composition and your body's processing efficiency.
Frequently asked questions
How many calories should I eat to lose weight?
Start from your maintenance calories (TDEE) and subtract 300–500 kcal per day for sustainable fat loss of approximately 0.5–1 lb per week. This is slow enough to preserve muscle mass and fast enough to produce visible results in 4–6 weeks. Going below 1,200 kcal per day for women or 1,500 kcal per day for men without medical supervision is generally not recommended, because these levels are difficult to meet nutritionally and can slow your metabolism further. A registered dietitian can help you set a personalized calorie target based on your weight, height, activity level, and goals.
What is the difference between BMR, TDEE, and calories?
BMR (Basal Metabolic Rate) is the calories you burn at complete rest — essentially the energy needed to keep your organs functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor, representing what you actually burn in a day including movement and exercise. When people say "calories" in the context of weight management, they usually mean TDEE. BMR is always lower than TDEE — typically by 20–40% depending on how active you are. Knowing your TDEE rather than your BMR is essential for weight management, because it is the number you eat relative to that matters for weight change.
Should I eat back the calories I burn exercising?
Generally no, for two reasons. First, calorie burn estimates from fitness trackers and online calculators are often 15–30% exaggerated, meaning you probably burned fewer calories than the number suggests. Second, appetite stimulation from exercise is a poor guide — research consistently shows that exercise does not reliably increase hunger proportionally to the calories burned, but neither does it reliably suppress appetite. Most people who "eat back" their exercise calories end up in maintenance or surplus. If your goal is weight loss and you are eating in a deficit, trust the deficit and do not eat back exercise calories unless you are consistently feeling faint, excessively hungry, or unable to complete your workouts.
How accurate are online calorie calculators?
Online calorie calculators are estimates based on population averages and are typically accurate to ±15–20% for most people. The formula itself (Mifflin-St Jeor) is one of the most accurate BMR equations, with about 10% average error compared to indirect calorimetry (the gold standard lab measurement). The bigger source of error is the activity multiplier — a single number cannot capture your actual movement pattern. A person who walks 10,000 steps a day but sits the rest of the time has a very different TDEE than a person with the same step count who also does resistance training, even if both fall under "moderately active." Treat the result as a starting point and adjust based on actual weight change over 2–4 weeks.
Do calories from protein count differently?
Yes — protein has a higher thermic effect than carbohydrates or fat. While dietary fat is absorbed with minimal processing (0–3% energy cost) and carbohydrates cost 5–10%, protein costs 20–30% of its calories to digest, metabolize, and store. This means the net calories your body actually gets from 100 kcal of protein is approximately 70–80 kcal, compared to 95–100 kcal from carbohydrates and virtually all 100 kcal from fat. This is one reason high-protein diets are often effective for fat loss — the net caloric intake is lower than the raw numbers suggest, and protein's satiety effect reduces overall food intake.
What is a healthy rate of weight loss?
0.5–1 kg per week (1–2 lb per week) is considered a safe and sustainable rate for most people. Faster rates of loss are usually achieved through very low-calorie diets that cause muscle loss, nutrient deficiencies, and metabolic slowdown. A good benchmark: if you are losing more than 1% of your body weight per week consistently, you are probably losing muscle as well as fat. Preserving muscle mass during a diet requires adequate protein (1.6–2.2 g/kg body weight), slow weight loss, and continued resistance training. Sustained fat loss over months and years requires habits you can maintain — extreme short-term diets that are abandoned after 8 weeks produce no lasting change.
How do hormones affect calorie needs?
Hormones significantly affect metabolic rate. Thyroid hormones (T3 and T4) regulate baseline metabolism — hypothyroidism can reduce BMR by 15–20%, while hyperthyroidism increases it. Sex hormones affect body composition and thus BMR: testosterone promotes muscle mass which burns more calories at rest, while estrogen promotes fat storage. During menopause, declining estrogen causes a metabolic shift that often results in weight gain even without changes in food intake. Cortisol, the primary stress hormone, elevates blood sugar and promotes fat storage, particularly visceral abdominal fat, when chronically elevated. These are reasons why identical calorie targets produce different results in different people — the hormonal environment determines how calories are partitioned between storage, muscle synthesis, and expenditure.
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For general wellness information only, not medical advice — see our disclaimer.