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For Windows server, we cover how the calculator works in the following document.
Each 2-processor license or each set of 16-core licenses are entitled to two instances of up to 8 cores, or one instance of up to 16 cores. The Azure Hybrid Benefit for Standard Edition licenses can only be used once either on-premises or in Azure. Datacenter Edition benefits allow for simultaneous usage both on-premises and in Azure.
So if you have 25 licenses that equates to 400 cores (25*400)
Using the pricing calculator that equates to 25 16-core VMs or 50 8-core VMs