In the Place Orders screen, when you are doing transfers, in the Supply Order Line Detail grid, StockIQ has several columns, all labeled "xxx To Transfer", where "xxx" is something like "On Hand", "Available", "Projected Available", or "Excess". There are also associated columns for "All Warehouse On Hand To Transfer" etc.
The addition of "...To Transfer" at the end is important and intentional, since it usually means that StockIQ is protecting, or "holding back" a portion of inventory that can be taken from the sending warehouse without causing shortages in that sending warehouse, e.g, how much you can take without getting into a "Rob Peter to pay Paul" type of situation.
Enabling/Disabling Transfer Protection
This protective feature is enabled by default. If you wish to disable it, then you can go to Settings --> System Configuration --> Substitute Order Settings, and uncheck the box that says "Protect Safety Stock At Source Site", and click Save:
Protection Calculation
The calculation works like this. StockIQ will start with the number identified in the column header, such as "Available", which is most common. StockIQ then subtracts out the safety stock quantity at the sending warehouse. Any amount above zero leftover is what can be transferred out of the sending warehouse without sending that warehouse's available quantity below safety stock. So, for example:
Available Quantity = 100
Safety Stock = 75
Available To Transfer = 100 - 75 = 25
A slightly more complex situation is when a warehouse is in a hub/spoke situation and has significant dependent demand. When this is the case, a good portion of safety stock is there directly in order to service the demand from the spokes. When this is the case, the amount of safety stock subtracted from the amount available to transfer is reduced by the percentage of independent demand that warehouse has (e.g. only for its own operations). Using similar numbers to the example above:
Available Quantity = 100
Safety Stock = 75
Safety Stock due to Independent Demand = 25
Available To Transfer = 100 - 25 = 75
In this way, StockIQ makes sure to hold back only what is necessary for the hub's own operations, and not protecting safety stock that is expressly there for the hub's usage.
The calculation is very similar for On-Hand to Transfer, Projected Available To Transfer, etc.