Zard Ab () is a village in Harazpey-ye Shomali Rural District of Sorkhrud District in Mahmudabad County, Mazandaran province, Iran.
At the time of the 2006 National Census, the village's population was 1,073 in 307 households. The following census in 2011 counted 1,213 people in 374 households. The 2016 census measured the population of the village as 1,071 people in 401 households.