Thanks for visiting the Community today, @sales-polarisusa. As an insight, the Inventory feature is only available in QuickBooks Online Plus.

When you convert your file from QuickBooks Desktop to the Online version, it will recalculate your inventory based on First-In, First-Out method.

Additionally, QuickBooks Online doesn't support units of measure for inventory items.

For additional details, check out this article to learn more about how features and data move from QuickBooks Desktop to QuickBooks Online.

You can also check out this article to get an overview of converting from QuickBooks Desktop to QuickBooks Online.

I'd be glad to guide you again if you have additional concerns about data migration. Take care!