A calorie surplus means you take in more energy than you burn over a longer period, so your weight goes up. When building muscle, a surplus is intended because it provides the energy for new tissue. The only question is how big it should be.
Small is enough
Muscle grows slowly, and extra energy does not make it grow faster. Whatever goes beyond what muscle building needs mostly ends up in fat tissue. In a study with elite athletes (Garthe et al. 2013), the group eating a good 600 kcal more per day gained clearly more fat, while lean mass did not differ between the groups.
A review on the off-season (Iraki et al. 2019) suggests roughly 10 to 20 percent above maintenance for beginners and intermediates, and closer to 5 to 10 percent for advanced lifters. Your trend weight should rise by about 0.25 to 0.5 percent of body weight per week.
From rate to calories
It is more practical to start from the rate you want: daily surplus = rate per week × body weight × 7,700 ÷ 7.
Example: At 80 kg and 0.35 percent per week, that is 0.28 kg per week and a surplus of about 310 kcal a day. With 2,800 kcal maintenance you end up at around 3,110 kcal. These numbers are a worked example.
Check it against your trend
Because your maintenance is itself an estimate, your surplus is only an assumption at first. Whether it fits shows in the slope of your trend weight after two to three weeks. The first week barely counts: more carbs refill your glycogen stores, and the scale jumps more than the surplus explains.