It will give you a quick overview of the SharePoint databases with properties like: Name, Server(Alias), TypeName, Web application name, Web application URL, Site collection count and the Size.
The size is actually the amount of disk space required for uncompressed backup. It might look something like a script, but actually it is a long and simple one-liner. You can see it below, I have used grave-accent(`) escape characters to fit it better in the blog. You can see it in one line here. Instead of piping to Format-Table you can generate CSV by piping to Export-CSV and later work with it in Excel.
Get-SPDatabase | Select-Object Name,@{Expression={$_.Server};Label="Server"},TypeName,@{Expression=`
{$_.WebApplication.Name};Label="WebAppLication"},@{Expression={$_.WebApplication.Url};Label="WebAppLicationUrl"}`
,@{Expression={($_.WebApplication.Sites | Measure).Count};Label="SC Count"},@{Label ="Size in MB";`
Expression ={$_.disksizerequired/1024/1024}} | Format-Table -AutoSize