2.25 inch / 57 mm square is fine for that base size. I would recommend getting a borderless chessboard at 18 inches squared to a bordered chessboard 19 to 20 inches squared. These are all within the 50 cm requirement you are seeking. However the 20 inch squared board is 50.8 cm if you are wanting to know. 18 inch squared borderless chessboard or a thin bordered 19 inch squared board are you only options if the 20 inch squared board is too big. Here's my 18 X 18 borderless board with 2.25 inch squares.
I am thinking of purchasing 4.1-inch king pieces and I am looking for a chess board as well. 2.25 inches square was recommended to me however, I do not want a too gigantic board in my house.
The king base is 43mm and I do not want my board to have longer length than 50 cm x 50cm
what should I do?