In summary, how to create a ratio between purchasing units and stock units that is unique to each product ?

Hello

I buy "raw material" products by kg and I use to mm. (Ex: 25 mm diameter steel bar purchased in kg but stored and consumed at millimeter)

The first idea would be to create a new category of units with two sub units (kg and mm)

But this is complicated when

- For the same diameter that coefficient may vary depending on the purchase and the material density

- I have a hundred different diameters

So the number of categories of unity becomes unmanageable

I would like to know if it is possible for each product ( raw material ) :

- To choose the unit of purchase (ie with a purchase price depending on the unit)

- To choose the management unit in the warehouse

- Enter the factor that connects those two units (which will enable to know the valuation in the warehouse)

and without that one is forced to choose these two units in the same category. (Systematic error)

This requires that the factor is specific to each product and not to each unit.

Thank you in advance for your ideas