The average bus between Costa Mesa and Diamond Bar takes 3h 16m and the fastest bus takes 2h 29m. There is a bus service every few hours from Costa Mesa to Diamond Bar. The journey time may be longer on weekends and holidays; use the search form on this page to search for a specific travel date.
Buses run hourly between Costa Mesa and Diamond Bar. The earliest departure is at 5:15 AM in the morning, and the last departure from Costa Mesa is at 10:27 PM which arrives into Diamond Bar at 6:44 AM. All services require a transfer at Bristol-Sunflower and take an average of 3h 16m. The schedules shown below are for the next available departures.


3h 14m • 2 changes

3h 2m • 2 changes

3h 1m • 2 changes

2h 55m • 2 changes

2h 37m • 2 changes

2h 37m • 2 changes

2h 39m • 2 changes

2h 40m • 2 changes

2h 29m • 2 changes

2h 29m • 2 changes

3h • 2 changes

3h 2m • 2 changes

2h 29m • 2 changes

2h 29m • 2 changes

3h • 2 changes

3h 2m • 2 changesWant to know about travelling from Costa Mesa to Diamond Bar? We have put together a list of the most frequently asked questions from our users such as: What is the cheapest mode of transport? What is the quickest option? How much do tickets usually cost? and many more.
No, there is no direct bus from Costa Mesa to Diamond Bar. However, there are services departing from Costa Mesa station and arriving at Diamond Bar station via Ring-Brea Mall. The journey, including transfers, takes approximately 3h 16m.
Costa Mesa to Diamond Bar bus services, operated by OCTA, depart from Bristol-Sunflower station.
Costa Mesa to Diamond Bar bus services, operated by OCTA, arrive at Diamond Bar Blvd and Sunset Crossing Rd station.
The distance between Costa Mesa and Diamond Bar is 44.2 km. The road distance is 51 km.
You can take a bus from Harbor-Bernard to Diamond Bar Blvd and Sunset Crossing Rd via Bristol-Sunflower, Ring-Brea Mall, and Brea Mall in around 3h 15m.