How far is the Golden Circle from Reykjavík?
The 230 km figure is the honest minimum: out to the three main sights and straight back with no detours. The 300 km figure that other guides quote includes the southern leg down Route 35 past Kerið to Selfoss and back on Route 1, which is what most tours actually drive. Both are right, which is why I write 230 to 300 km depending on the detours.
Distance is not what makes the day long. Pure driving is a bit over three hours; the other three to five are spent standing at four stops, and on a coach, waiting for forty other people to come back to it.
The roads, in order: Route 1 out of Reykjavík, Route 36 to Þingvellir, 365 and 37 across past Laugarvatn to Geysir, Route 35 to Gullfoss and then back down past Kerið to Selfoss. All paved, all ordinary in summer. Þingvellir itself sits 40 to 45 km northeast of the city.
For the record, Keflavík International Airport is 45 to 50 minutes from Reykjavík in the other direction, which matters if you are trying to fit the loop around a flight; the private tour is the only one that will collect you at the airport. How the distance turns into hours is on how long the Golden Circle takes.
Frequently asked questions
How many kilometres is the Golden Circle?
230 km if you drive to the three main sights and back with no detours, and up to 300 km with the Kerið and Route 35 southern leg that most tours include.
How long is the drive from Reykjavík to Þingvellir?
About 45 km and roughly an hour on Route 36. From there it is 61 km to Geysir and ten more minutes to Gullfoss. Gullfoss back to the city is about an hour and a half direct.
Can you visit the Golden Circle from Keflavík airport?
Yes, on the private tour, which picks up at the airport as well as at Reykjavík hotels. The airport is 45 to 50 minutes from the city — see the loop on your first day.