Find out exactly how many calories you need each day based on your age, sex, weight, height and activity level. Set your goal to lose weight, maintain your current weight or gain muscle — the calculator adjusts your target accordingly.
This calculator uses the Mifflin-St Jeor equation — the most accurate formula for estimating Basal Metabolic Rate (BMR) for most people. BMR is the number of calories your body burns at complete rest just to maintain basic functions.
BMR is then multiplied by your activity level to give your Total Daily Energy Expenditure (TDEE) — the number of calories you burn in a typical day.
A deficit of 500 calories per day leads to approximately 0.5kg of weight loss per week. This is considered a safe and sustainable rate. Avoid dropping below 1,200 calories (women) or 1,500 calories (men) without medical supervision.
Calorie requirements typically decrease by about 2-8% per decade after age 30 due to several physiological changes. Muscle mass naturally declines with age through sarcopenia, and since muscle tissue burns more calories at rest than fat tissue, your basal metabolic rate decreases. Hormonal changes also play a role: testosterone decreases in men and estrogen in women during menopause, both affecting metabolism and body composition. Activity levels often decline with age due to lifestyle changes, retirement from physical jobs, or reduced exercise capacity, further lowering total daily energy expenditure. However, these declines aren't inevitable — strength training preserves muscle mass and maintaining high activity levels can keep metabolism elevated even into your 60s and 70s. The formulas account for average age-related changes, but an active 50-year-old who lifts weights may need more calories than a sedentary 30-year-old. This is why simply eating the same amount you did in your 20s often leads to gradual weight gain in your 40s and 50s. You need to either reduce portions slightly each decade or increase activity to compensate for the metabolic slowdown. Genetic factors also influence how dramatically metabolism changes with age — some people maintain high metabolic rates longer than others.
Calorie calculators provide estimates that can be 10-20% off your true needs in either direction. They're based on population averages and don't account for individual variations in metabolism, genetics, muscle mass, hormone levels, or thermogenic efficiency. Someone with more muscle mass burns more calories than the calculator suggests for their weight, whilst someone who has lost significant weight may have adaptive thermogenesis making their metabolism lower than predicted. Medical conditions like hypothyroidism, PCOS, or insulin resistance affect metabolism in ways formulas don't capture. Medications including antidepressants, beta-blockers, and steroids can alter calorie needs. Even fidgeting (NEAT - Non-Exercise Activity Thermogenesis) varies hugely between people and can account for 200-500 daily calorie differences. The only way to know your true needs is through tracking: use the calculator as a starting point, eat that amount for 2-3 weeks, and adjust based on whether your weight changes as expected. If the calculator says 2,000 calories for maintenance but you're losing weight, you actually need more — try 2,200. If you're gaining, drop to 1,800. Think of the calculator as providing a ballpark figure to begin experimentation, not an exact prescription. This is normal and expected — individual metabolic variation is real and significant.
Both approaches work, and personal preference should guide your choice. Eating the same calories daily provides consistency and simplifies tracking: you know your portions, meal prep is routine, and there's no calculation each day. This works well for people who thrive on structure and routine. However, varying calories based on activity can be more optimal physiologically: eating more on training days provides fuel for performance and recovery, whilst eating less on rest days matches lower expenditure. Athletes often carb cycle or calorie cycle this way. Some people naturally prefer eating more some days and less others, and calorie banking (eating less Mon-Fri to "save" calories for weekend social events) can improve dietary adherence. The weekly total matters more than daily precision — 14,000 calories across a week works whether that's 2,000 daily or varying between 1,700 and 2,300. Flexible approaches often improve long-term sustainability because they accommodate real life better than rigid daily targets. That said, excessive variation can disrupt hunger cues and make it harder to establish healthy habits. A middle ground works well: aim for your target most days with 10-20% flexibility for particularly active or sedentary days and social occasions. Don't stress if one day is 500 calories over target — just return to your usual eating the next day rather than trying to compensate with extreme restriction.
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 650 + 1,031 − 150 − 161 = 1,370 kcal. TDEE = 1,370 × 1.55 (moderately active) = 2,124 kcal. For weight loss: 2,124 − 500 = 1,624 kcal daily. For maintenance: 2,124 kcal. For muscle gain: 2,124 + 500 = 2,624 kcal. Weekly total for maintenance: 14,868 kcal.
BMR = (10 × 80) + (6.25 × 180) − (5 × 25) + 5 = 800 + 1,125 − 125 + 5 = 1,805 kcal. TDEE = 1,805 × 1.725 (very active) = 3,114 kcal. For weight loss: 3,114 − 500 = 2,614 kcal. For maintenance: 3,114 kcal. For muscle gain: 3,114 + 500 = 3,614 kcal. This active individual can eat substantially more than a sedentary person while maintaining weight.
BMR = (10 × 70) + (6.25 × 160) − (5 × 50) − 161 = 700 + 1,000 − 250 − 161 = 1,289 kcal. TDEE = 1,289 × 1.2 (sedentary) = 1,547 kcal. For weight loss: 1,547 − 500 = 1,047 kcal (too low — minimum should be 1,200). Better deficit: 1,547 − 300 = 1,247 kcal for safer, sustainable loss. Illustrates how older sedentary individuals have lower calorie needs and must be careful not to create excessive deficits.
Start with the calculator's recommendation and track your weight weekly for three weeks. If losing/gaining as expected, you've found your number. If not, adjust by 100-200 calories and retest. Remember that weight fluctuates daily due to water, sodium, and digestive contents — track the trend, not individual weigh-ins. Focus on whole foods that provide satiety: protein, fiber and healthy fats keep you full on fewer calories than processed foods. Eat adequate protein (1.6-2.2g per kg bodyweight) especially when in a deficit to preserve muscle mass. Don't fear occasional higher-calorie days — they can boost leptin and prevent metabolic adaptation during long diet phases. Consider non-scale victories: measurements, photos, how clothes fit, energy levels, and performance improvements often change before scale weight budges. Menstruating women should track across full cycles as hormones affect water retention significantly. Remember that NEAT matters enormously: someone who paces while on calls, takes stairs, and fidgets can burn 300-500 more daily calories than someone identical who sits still. Building muscle through strength training raises your BMR permanently, allowing higher calorie intake. Sleep quality and stress affect both calorie burn and hunger hormones — prioritizing 7-9 hours sleep and stress management supports your metabolic health as much as hitting calorie targets. Finally, sustainability beats perfection: hitting 80% of your calorie target consistently beats perfect adherence for two weeks followed by abandonment. The best calorie target is one you can maintain long-term while enjoying food and living life.