The average bus between Diamond Bar and Costa Mesa takes 3h 40m and the fastest bus takes 2h 36m. There is a bus service every few hours from Diamond Bar to Costa Mesa. 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 Diamond Bar and Costa Mesa. The earliest departure is at 6:34 AM in the morning, and the last departure from Diamond Bar is at 10:33 PM which arrives into Costa Mesa at 5:38 AM. All services require a transfer at Brea Mall and take an average of 3h 40m. The schedules shown below are for the next available departures.


3h 15m • 2 changes


3h 13m • 2 changes


3h 13m • 2 changes


3h 19m • 2 changes


3h 15m • 2 changes


3h 13m • 2 changes


3h 13m • 2 changes


3h 19m • 2 changes


3h 15m • 2 changes


3h 13m • 2 changes


3h 13m • 2 changes


3h 19m • 2 changes
Want to know about travelling from Diamond Bar to Costa Mesa? 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 Diamond Bar to Costa Mesa. However, there are services departing from Diamond Bar station and arriving at Costa Mesa station via Brea Mall. The journey, including transfers, takes approximately 3h 40m.
Diamond Bar to Costa Mesa bus services, operated by Foothill Transit, depart from Diamond Bar Blvd and Sunset Crossing Rd station.
Diamond Bar to Costa Mesa bus services, operated by Foothill Transit, arrive at 19Th-Harbor station.
The distance between Diamond Bar and Costa Mesa is 44.2 km. The road distance is 54 km.
You can take a bus from Diamond Bar Blvd and Sunset Crossing Rd to 19Th-Harbor via Brea Mall, Ring-Brea Mall, and Bristol-Sunflower in around 2h 55m.