Each attraction inside a Disney theme park has a certain capacity, or a maximum number of guests that attraction can handle in a given operating day. For example, a ride-through attraction like the Haunted Mansion may be able to carry 2,000 guests per operating hour. During a 12-hour operating day, 24,000 guests can experience this attraction. Similarly, a live theatrical show with a theatre capacity of 3,000 guests that has five shows during the day has a capacity of 15,000 guests. When Fastpass is installed on the attraction, a certain number of those seats (in the theatre, on the ride vehicles, etc.) are set aside. The remainder are made available on a "stand-by" basis to other park guests.
At the start of the operating day, the enabled attraction's wait is pre-set at a given time (for example, 45 minutes). The number of Fastpasses available is evenly divided into time intervals (usually five minutes, but sometimes three minutes). As guests obtain Fastpasses for the attraction, time intervals are depleted, moving the return time to later in the day. For an average attraction, the Fastpass wait will generally stay near this initial pre-set time.
In the case of very popular attractions, such as Splash Mountain or other major thrill rides, time intervals are depleted quickly, resulting in longer virtual waits. Sometimes, all the time intervals will be depleted early in the day, at which point Fastpasses are no longer obtainable for the given attraction during that day.
Disney Fastpass tickets are dispensed by machines outside each attraction that uses them. The guest inserts his/her park ticket into a reader on the machine. The machine then returns the admission ticket and a Fastpass ticket will be printed. This ticket will show the time at which the guest may enter the special priority line at that attraction. The time period given is normally one hour for rides, and 15 minutes for theatrical presentations. It will also show when another Fastpass can be obtained.
In normal practice, only one Fastpass ticket can be held at a time. Another Fastpass ticket can be obtained either at the start of the current Fastpass ticket's return time or after two hours, whichever is earlier. If a guest attempts to obtain another Fastpass before these times, an informational ticket will be printed indicating when the next Fastpass ticket can be obtained.
The presence of Fastpass on an attraction does not imply that Fastpass tickets will be offered on any given day. During less-crowded operating days, the system may not be used on certain attractions as the stand-by wait is expected to be short enough to make Fastpass unnecessary. Fastpass is generally not used at all during separate-ticket events, such as Mickey's Very Merry Christmas Party or Grad Nite, or during special after-hours events for resort guests or annual passholders, although exceptions do occur.
- Normally one can only carry two Fastpasses at one time. One at Disneyland and another at California Adventure. Actually, one can carry three. A fastpass for any ride at Disneyland, one at California Adventure, and another for Roger Rabbits cartoon Spin. This is because for some reason Roger Rabbit is part of another Fastpass category. Another similar mechanism makes it possible to hold 6 per person at once, one for DL, one for DCA, one for Roger Rabbit's Car-Toon Spin, one for Radiator Springs Racers, one for a show at DL (ex. Fantasmic), and one for World of Color.