The industry standard suggests that each couple will need 9 sq ft per couple (that’s over 4.5 ft per person). Example: Let’s assume a party has 200 guests. 40%, or 80 guests, will be dancing at any one time. This means that you would need approximately 360 square feet of dance floor for this party, or a 15×20 dance floor.
If you figure 40 of 100 guests will dance, then you need about a 200 square foot dance floor. If you double that for 200 guests you would need a 400 square foot dance floor. With 300 guests you need a 600 foot dance floor. You can see how easily that rule could get out of hand. So again you have to consider other factors like the age of your guests and how many people you really think will be dancing at one time.