When placing chairs around a conference table, note that:
In both cases, you will need a minimum of 75 cm / 29.5" behind the chairs for clearance.
The dimension required around a meeting room table depends on the number of people it accommodates:
The space in front of a whiteboard should be large enough for the presenter to move freely and write comfortably. In that respect, ensure a clearance of 120 cm - 150 cm~ / 47.2" - 59.1" in front of it, which will enable approaching it from various angles.
Meeting rooms often facilitate presentations. Therefore, it's essential to place a screen in an adequate size within a reasonable distance from the conference table.