If this value is meters, the feet equivalent will be larger.
If you are uncertain of the units, the meta data should indicate the vertical units.
If there is no metadata, add the USATopo layer to your map and compare the values of the raster to the contour values of the topo.
If you are sure of the vertical units, why not simply use the raster calculator to multiply by the correct conversion value, and use the resulting raster instead of the original?
Thank you for that response Jim! Maybe because it's a new year but after reading your reply, I came to the realization all I had to do to find my answer was look at the properties of the data layer and look for the Vertical Units.