To calculate occupancy rate, divide the time that a unit was rented out by the time the unit was available for rent. Another option is to divide the total number of units that are rented out by the total number of units.
Which formula is used depends on the information required. If the occupancy rate of a single unit is required, then the ratio of the time the unit is rented to the time it was available is appropriate. To find the general occupancy rate of a set of units during a specific time period, use the number of units occupied over the total number of units available.