This is based on the minimum size of the bath so if you’re going for a bigger bath the 5ft side of this bathroom will change slightly. This is one of the standard layouts for small bathroom floor plans. Small bathroom dimensions (shower, toilet and sink) 6ft x 6ft (1.8m x 1.8m) This is one of the standard layouts for small bathroom floor plans. Half bathroom dimensions (toilet and corner sink, pocket door) 5ft x 3ft (1.5m x 0.9m). The minimum you're allowed by code in the US is 5ft x 2.5ft (1.5m x 0.76m).