Moving your infrastructure to the cloud is not always an easy task, especially when we talk about costs, which is, most likely, the main reason to do the migration.
The cost prediction can be less painful using the Pricing Calculator, this tool can save you a lot of time and also headaches during your journey to the cloud, all the main cloud providers have their own pricing calculator.
Azure
https://azure.microsoft.com/en-us/pricing/calculator/
AWS
GCP
https://cloud.google.com/products/calculator
Use this tool in your favor not only during the migration phase but always when you need to estimate a new application/infrastructure.
Hope this can be useful to you!