I am attempting to use the IDW (Spatial Analyst) tool in a Python script however I am a bit confused on what to put for the "Cell Size" optional parameter. When using the tool within ArcMap it seems to calculate this variable for you when the input is selected(pictured),however I am unsure if when scripting I would have to calculate it manually or if I leave it blank ArcMap will calculate it when I run the script?

Not sure if it matters but the script is not Stand Alone it will be used as a scripting tool run in ArcMap

![Cell Size](https://i.stack.imgur.com/AhvYz.jpg)