Whenever I have spoke to customers about assessing their server estate to understand if it's Azure readiness and understand costs within Azure, the question has always been "Can I use the spreadsheet that I've got with my server inventory?" and unfortunately the answer was no, until the Azure Migrate product team announced at Microsoft Ignite in November 2019 that they were adding that functionality into the tooling!
If you have your server inventory stored within a spreadsheet you can now take it and use it within Azure Migrate and perform an assessment on that data. There is a template CSV file that you need to follow in terms of formatting but the information it is looking for is the type of information you would expect, server name, server operating system, number of disks, server types, etc. You can find out more about the CSV formatting and what you need to do to prepare it for import into Azure Migrate here.
I've recorded a short video that shows you the process of taking the spreadsheet and importing into Azure Migrate, I even show you how to troubleshoot it when the formatting of your spreadsheet isn't right and showcase the information that you get back from Azure Migrate about your environment.
The feature is currently in preview at the moment, and generally while Azure services or products are within that part of the service lifecycle I wouldn't recommend utilising them within a production environment, however I personally think this is a service you can use now. So don't delay, take your server inventory and evaluate it for a move to Azure!