I am working with elevation data and performed a local operation to convert it from meters to feet.
I am interested in finding the area (expressed in percentage) that is above 4,000 feet, but I am having difficulty recalling how to do this.
You can use the Con (Spatial Analyst) tool to calculate the area of specified elevation values. In this example, I stated that I wanted all elevation values of a floating point DEM > 400 = 1, else = 0. The black and yellow image is the result (Figure 1). Then, simply open the attribute table and look at the count next to the Value = 1 row (Figure 2). These units will be in map units, so in this case 350,850 m^2 or 0.35 km^2. As a percentage, elevation values >400m make up 39% of the area.
If your elevation raster is integer, Build Raster Attribute Table. Then, select the rows in the table of interest, and look at the Statistics for the Count field (right-click 'Count' -> Statistics). The SUM value is the number of pixels selected. Multiply this value by the area of one pixel (raster layer properties -> Source tab -> cell size). Repeat with no selection to get total area, or extract from raster properties (Source tab -> Columns and Rows). Divide to get percentage.