| Country: | ISL |
| Type: | Primary |
| Route: | 40 |
| Map: | Iceland Route 40.png |
| Length Ref: | [1] |
| Direction A: | Northern |
| Terminus A: | Sæbraut |
| Junction: | Miklabraut |
| Direction B: | Southern |
| Terminus B: | Reykjanesbraut |
Route 40, known as Icelandic: Hafnarfjarðarvegur in Icelandic pronounced as /ˈhapnarˌfjarðarˌvɛːɣʏr̥/ in Icelandic or by its busiest stretch, Icelandic: Kringlumýrarbraut in Icelandic pronounced as /ˈkʰriŋlʏˌmiːrarˌprœyːt/, is one of the two major traffic arteries running across Capital Region.[2] [3]