UOM factor and base unit for items

ERPNext
1

so the uom do we go by the unit in each packaging or the box for example

200 each/box, 20 box/case
does that go
each conversion factor 1
box conversion factor 200
case conversion factor 20
or do i do go
each conversion factor 1
box conversion factor 200
case conversion factor 4000

2

You broke the logic in your question so it’s impossible to answer it.

Basically you have:

200 each per box,

20 box per case.

When you ask about a conversion factor, you MUST include the FROM and TO (measurement) units.