The road starts at the junction of the R117 (Milltown Road from the west and Sandford Road from the north) and R824 (Eglinton Road). A bridge crosses the River Dodder shortly before a junction with the Beach Hill and Beaver Row road that connects to Donnybrook. The road is known as the Clonskeagh Road until it reaches the triangle in Clonskeagh.
At the triangle,[clarification needed] the road connects with Bird Avenue before continuing south as the Roebuck Road.
Further along the Roebuck road leads off to the west before connecting with the R112 at Foster Avenue while the R825 stays south known as the Goatstown Road.
The first section of the route terminates at the crossroads in Goatstown as the road continues south as the R133, while east and west runs the R112.
Just under 1 km further south the road starts again at the junction with the R133 and heads in a westerly direction towards Stillorgan. The road is briefly known as Drummartin Road at this point before it connects with the old route of the Lower Kilmacud Road.
After Stillorgan, the road crosses the N11 and is known as Stillorgan Park for 1 km before the road takes a left at a T-Junction and heads north as Carysfort Avenue.[citation needed]
The road terminates at the end of Carysfort Avenue where the road joins up to the N31 at Frascati Road, Blackrock.[citation needed]
