Calorie Surplus Calculator
Muscle gain is limited by training and recovery, not by how much you eat. A modest surplus supplies the rate your body can actually use; a large one adds fat.
Your results
Not all of the weight gained will be muscle. Expect closer to 1:1 muscle-to-fat in your first year of training and considerably worse after several years.
Why a small surplus is enough
A first-year lifter might build 0.7–1.1 kg of muscle in a good month. By the fourth year that may be 0.1–0.35 kg. Eating 1,000 kcal over maintenance does not change those numbers — it changes how much fat arrives alongside them.
200–350 kcal above maintenance supplies the rate comfortably. Beginners can use the higher end; experienced lifters should use the lower.
Where to stop
Around 15–18% body fat for men and 25–28% for women is a sensible ceiling — beyond that, the ratio of muscle to fat gained gets worse. By measurement: if your waist has grown more than about 4–5 cm from where you started, the surplus is too large.
And if your lifts have not improved in six weeks, more calories are not the answer. The programme is.
Common questions
How fast should I gain?
0.25–0.5% of body weight per week. Beginners at the top, experienced lifters at the bottom.
Can I build muscle without gaining fat?
Beginners, people returning after a layoff, and people with fat to lose often can. Trained and lean, expect some fat alongside.
Why is my weight up 2 kg in a week?
Not muscle. More food means more glycogen, water and gut contents.
How long should a bulk last?
16–24 weeks, then maintenance or a short cut.
Related calculators
Track the numbers, not just calculate them
MyFitsy stores your weight, measurements and every session, so the figures above become a trend instead of a one-off.
