Weight Gain Calculator
Calculate your daily calorie surplus target and estimate how many weeks it will take to reach a target weight gain.
Gender
Age
Height
cm
Weight
Activity Level
Gain Pace
Target weight gain
kg
Maintenance calories
2,391 kcal/day
Target surplus calories
2,941 kcal/day
Daily surplus
550 kcal
Time to gain 5kg
~10.0 weeks
How the Weight Gain Calculator Works
This calculator finds your maintenance calories (via the Mifflin-St Jeor equation and your activity level), then adds a daily calorie surplus based on the bulking pace you choose. It also estimates how many weeks it'll take to reach a target weight gain, using the rough estimate that 1 kg of body weight ≈ 7,700 kcal.
How to Use It
- Enter your age, gender, height, and weight.
- Select your activity level and bulking pace — lean, moderate, or fast.
- Enter a target weight-gain amount to see a rough timeline.
Example
A moderately active person with 2,200 maintenance calories choosing a moderate 550 kcal/day surplus would eat around 2,750 calories/day, and take roughly 10 weeks to gain 5kg.
Common Use Cases
- Setting a daily calorie target for a lean bulk or mass-gain phase.
- Planning meals for hard-gainers who struggle to eat enough to gain weight.
- Estimating a realistic timeline for a weight or muscle-gain goal.
FAQs
How big a calorie surplus should I eat to gain weight?
A surplus of 250–500 kcal/day (a "lean bulk") tends to favor muscle gain over fat gain compared to a larger surplus, though the exact split between muscle and fat also depends on training, protein intake, and genetics. Faster bulks pack on weight quicker but with more fat.
Why 7,700 kcal per kg?
It's the standard estimate for the energy stored in 1 kg of body tissue, used here for a rough timeline. Actual weight gain includes water, muscle, and fat in a mix that varies by person and training program, so treat the estimate as a starting point rather than an exact prediction.
How is this different from the Calorie Calculator?
The general Calorie Calculator gives calorie targets for several goals at once (loss, maintenance, gain). This tool is built specifically around a weight-gain goal, letting you pick a bulking pace and see an estimated timeline to a target weight gain.