Sang Bast () is a village in, and the capital of, Sang Bast Rural District in the Central District of Fariman County, Razavi Khorasan province, Iran.
At the time of the 2006 National Census, the village's population was 670 in 187 households. The following census in 2011 counted 803 people in 226 households. The 2016 census measured the population of the village as 786 people in 243 households.