What Is the Weight Gain Calorie Calculator?
This calculator estimates how many calories you should eat per day to gain weight at a chosen rate. It first works out your maintenance calories (Total Daily Energy Expenditure, or TDEE), then adds the surplus required to put on your target amount of body mass each week. It is ideal for anyone bulking, building muscle, or recovering lost weight.
How to Use It
Enter your gender, weight in kilograms, height in centimetres, age, and activity level. Then choose how fast you want to gain weight in kilograms per week — a common lean-bulk target is 0.25 kg/week. The tool returns your daily calorie goal along with your BMR, TDEE, and the daily surplus.
The Formula Explained
BMR is calculated with the Mifflin-St Jeor equation: \(10\times\text{weight} + 6.25\times\text{height} - 5\times\text{age} + 5\) for men (−161 for women). Multiplying BMR by your activity factor gives TDEE. Because roughly 7,700 kcal stores 1 kg of body mass, gaining g kg per week needs an extra \(g \times 7700 \div 7\) calories each day. Adding this surplus to TDEE gives your target.
$$\text{Target} = \text{BMR} \times \text{Activity} + \frac{\text{Gain (kg/week)} \times 7700}{7}$$ $$\text{where}\quad \text{BMR} = 10\,\text{Weight} + 6.25\,\text{Height} - 5\,\text{Age} + 5$$
Worked Example
A 25-year-old man weighing 70 kg at 175 cm who is moderately active (×1.55) and wants to gain 0.25 kg/week: BMR = 10×70 + 6.25×175 − 5×25 + 5 = 1,673.75. TDEE = 1,673.75 × 1.55 ≈ 2,594. Surplus = 0.25×7700÷7 = 275. Target ≈ 2,869 calories/day.
$$\text{BMR} = 10\times70 + 6.25\times175 - 5\times25 + 5 = 1{,}673.75$$ $$\text{TDEE} = 1{,}673.75 \times 1.55 \approx 2{,}594$$ $$\text{Surplus} = 0.25\times7700\div7 = 275$$ $$\text{Target} \approx 2{,}869 \text{ calories/day}$$
FAQ
How fast should I gain weight? For lean muscle gain, 0.25–0.5 kg per week is usually recommended to limit fat gain.
Is 7,700 calories per kg exact? No — it is a widely used estimate for body mass. Track your progress and adjust intake every 2–3 weeks.
Should I eat more protein? Yes. While calories drive weight gain, adequate protein (around 1.6–2.2 g/kg) helps ensure the gain is muscle rather than fat.
