Calorie Calculator: Lose, Maintain or Gain Weight
Calories are the basic unit of the energy game: eat more than you burn and you gain weight; eat less and you lose it. This free calorie calculator does the arithmetic for you — it estimates your TDEE from your age, size and activity, then tells you exactly how many calories to eat per day to lose, maintain or gain weight at a pace you choose.
Calorie Calculator
How to Use This Calorie Calculator
Enter your sex, age, weight and height, choose metric or imperial units, and pick the activity level that matches your typical week. Together these produce your maintenance calories — the number you can eat without gaining or losing weight.
Next, choose your goal: lose weight, maintain, or gain. If you chose lose or gain, pick a pace — slow (about 0.25 kg per week), moderate (0.5 kg per week) or aggressive (0.75 kg per week). Click Calculate and you get a single daily calorie target.
The tool also shows the math behind it: your BMR, your maintenance calories and your weekly change. If your target would land below a safe floor (1,200 calories for women, 1,500 for men), the calculator clamps it and warns you — pick a slower pace instead.
The Formula
The calculation runs in two steps. First, your TDEE: TDEE = BMR × activity factor, where BMR uses the Mifflin-St Jeor equation (10 × kg + 6.25 × cm − 5 × age + 5 for men, − 161 for women) and the factor ranges from 1.2 (sedentary) to 1.9 (athlete).
Second, the adjustment. A pound of body fat holds about 3,500 calories, so 0.25 kg is roughly 1,925 calories — about 275 calories per day. Each pace step therefore moves your target by 275 calories: losing subtracts 275, 550 or 825 per day; gaining adds the same amounts; maintaining changes nothing.
Worked example: a 30-year-old man, 70 kg and 170 cm, moderately active, has a BMR of about 1,618 calories and a TDEE of 1,618 × 1.55 ≈ 2,508 calories. To lose 0.5 kg per week, he eats 2,508 − 550 = 1,958 calories per day.
Tips for Hitting Your Calorie Target
Weigh and measure your portions for at least the first few weeks. Studies consistently show people underestimate what they eat by 20 to 30%, and that gap is often the whole difference between losing and stalling.
Reassess after 10 lb (4.5 kg) of change — your maintenance drops by roughly 45 to 85 calories per day as you get lighter, so the same intake stops working. Recalculate and reset your target.
Protein matters more than any other macro while you cut: aim for 1.2–2.2 g per kg of body weight to protect muscle and stay full. The Macro Calculator turns your calorie target into gram targets.
Frequently Asked Questions
How many calories should I eat to lose weight?
Start from your maintenance (TDEE) and subtract 300–550 calories a day. A 500-calorie daily deficit gives roughly 1 lb (0.45 kg) of fat loss per week — about 0.5 kg. Going much more aggressive than that rarely speeds results and often costs you muscle and energy.
Why can't I eat fewer than 1,200 (or 1,500) calories a day?
Below about 1,200 calories for women or 1,500 for men, it becomes very hard to get enough protein, vitamins and minerals, and muscle loss and fatigue become likely. Very low intakes can also slow your metabolism and rebound into bingeing. If your target lands there, slow the pace — not the floor.
How many calories are in a pound of fat?
About 3,500. That is where the classic "500 calories per day for 1 lb per week" rule comes from — 500 × 7 = 3,500. In metric terms, 1 kg of fat stores roughly 7,700 calories, which is why this calculator uses daily deficits of 275, 550 and 825 calories for 0.25, 0.5 and 0.75 kg per week.
Why am I not losing weight even in a calorie deficit?
Check your logging first — underestimating portions by a couple of hundred calories is the most common cause. Also make sure you used an honest activity level, and remember water retention and normal daily fluctuations can hide fat loss for a week or two. Judge the trend after 3–4 consistent weeks before changing anything.
Do I need to count calories forever?
No. Most people use counting for a few months to learn what a sensible portion looks like, then switch to looser habits — weighing occasionally and eating mostly whole foods. Revisit counting when you change goals or if your weight drifts.