For a dinner party, you will need approximately twenty (20) square feet per person, which equates to a space roughly fifty (50) feet wide by one hundred (100) feet long.  However, these dimensions may vary depending on your table sizes and whether you are planning a dance floor.  Cocktail parties typically require half the space.  

To ensure you have enough room for your guest to comfortably move around and enjoy themselves, it's crucial to consider these factors in advance.