Calorie Calculator
Estimate your daily calorie needs with the Mifflin-St Jeor equation, then pick a goal — lose, maintain or gain. 用 Mifflin-St Jeor 公式估算每日所需热量，再选择你的目标。
Calories in versus calories out is the physics of body weight, and this calculator estimates both sides of the equation. Enter your age, sex, height, weight and activity level, and it computes your Basal Metabolic Rate (BMR), scales it to your Total Daily Energy Expenditure (TDEE), and shows three goal targets: a steady fat-loss intake, the maintain intake, and a modest surplus for building muscle.
The math uses the Mifflin-St Jeor equation, the most validated BMR formula for the general population: 10 × weight(kg) + 6.25 × height(cm) − 5 × age, plus 5 for men or minus 161 for women. Your BMR is what you burn lying still all day — typically 1,400 to 1,800 kcal for adults. The activity multiplier then reflects real life: sedentary is ×1.2, light exercise ×1.375, moderate ×1.55, active ×1.725 and very active ×1.9. Be honest here — most people overestimate their activity, and it is the largest lever in the whole calculation.
The goal cards use standard, sustainable rates: lose weight at roughly 500 kcal below TDEE (about 0.5 kg per week), maintain at TDEE itself, and gain with a 300 kcal surplus (about 0.3 kg per week). Aggressive cuts backfire — your body adapts, hunger wins, and the weight returns. The slow deficit, tracked over weeks rather than days, is what actually works; daily weight swings from water and food can be larger than the weekly fat change you are measuring.
Remember this is an estimate, not a prescription. Medical conditions, medications and unusual activity patterns shift real expenditure. And for the other half of the picture — what that intake means for your body composition — the BMI Calculator places your weight in context.
Frequently asked questions
What formula does this calculator use?
The Mifflin-St Jeor equation is the most validated BMR formula for the general population, outperforming older equations like Harris-Benedict in most studies. It is not perfect — athletes and older adults may differ — but it is the standard starting point.
How many calories should I eat to lose weight?
The classic guidance: lose about 0.5 kg per week by eating 500 kcal below your TDEE. Cutting harder is slower metabolically and hard to sustain; the steady deficit wins over months.
How many calories should I eat to gain muscle?
Roughly 300–500 kcal above your TDEE, paired with resistance training. Without training, a surplus mostly becomes fat — the weights are what tell your body to build muscle.
What is the difference between BMR and TDEE?
BMR is what your body burns at complete rest (breathing, heartbeat, keeping warm). TDEE is BMR multiplied by your activity level — the total you actually burn each day. Your BMR never changes with exercise; your TDEE does.