Windmill Hill Cutting, Railway cutting east of Toodyay, Western Australia, Australia

Windmill Hill Cutting is a railway cutting east of Toodyay in Western Australia, on the dual gauge Eastern Railway through the Avon Valley. It was drilled and blasted through solid granite to a depth of almost 35 metres and a length of 175 metres, with about 3 million cubic metres of rock excavated between 1963 and 1964.

The railway was built in the early 1960s to connect Perth with other states and improve transportation across the region. This project marked an important step in developing the area's transport network.

The cutting's name comes from Windmill Hill, the rise it slices through; planners had intended to bore a tunnel there before drilling and blasting the granite instead. A plaque at the lookout records the depth as 35 metres and the length as 175 metres, and the exposed rock led to the site being nominated as a geological heritage site in the 1990s.

The site is accessible from Northam-Toodyay Road with a clearly marked gravel parking area. Walking shoes are recommended since the approach involves uneven terrain and the viewing point requires some walking from the parking area.

A lookout plaque at the cutting states it is 35 metres deep and 175 metres long, claiming it as one of the deepest in Australia. The site was nominated as a geological heritage site in the 1990s because the excavation exposes the underlying rock formations.