Hi @Sylar Liu ,
without any details it's hard to answer your very generic question.
We have mid-size customers (my definition of "mid-size") which are spending a few hundred $ per month up to 20 - 40k $ per month.
It all depends on "which Azure services", "how many Azure services", "which sizes of Azure services" and "in which region the Azure services" are consumed.
The Azure Price Calculator is a good option to get an idea about the pricing for Azure Services: https://azure.microsoft.com/en-us/pricing/calculator/
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Regards
Andreas Baumgarten