Otoyol routes in Turkey follow a regional based two-digit numbering system. All routes have the prefix O on all signage and maps. Motorways that start in the Marmara region are all single digit. Motorways that start in The Central Anatolia Region have a first digit of two. Motorways starting in the Aegean Region have a first digit of three. Motorways starting in the Mediterranean Region and Southeastern Anatolia Region have a first digit of five. The O-21A is the only motorway to have a letter assigned to it. Most motorways in Turkey have six lanes (3+3 lanes), however there are sections of some motorways with only four (2+2) lanes. The motorways extended to 28 of the country's 81 provincial-level administrative divisions.
As of October 2024, there are 3,796 km of toll motorways network (otoyollar) in service.