The perimeter of a square can be calculated using the formula:
\[ \text{Perimeter} = 4 \times \text{side length} \]
For a square with a side length of 12 cm, the perimeter would be:
\[ \text{Perimeter} = 4 \times 12 , \text{cm} = 48 , \text{cm} \]
Therefore, the perimeter of the square is 48 cm.