The financials for figuring out if it is better (a.k.a. cheaper) to go cloud is an easier thing to figure out than figuring out if it is better for you (a.k.a. easier).
Cloud providers charge for usage in ways that you don't take into account when you own your entire infrastructure. Such charges may include any or all of the following:
- Hours of run-time per server instance, per instance type (744/hours per month for 24/7 servers)
- Extra cost for added CPU/RAM options for instance types
- Use of specialist cloud infrastructure
- Some offer network loadbalancers as a discrete service
- Some offer simple file-storage as a discrete service
- Network transfer between the cloud and the Internet
- Network transfer between server instances within the cloud
- Storage transfer between server instances and storage
This can make estimating your monthly costs quite hard if you don't know how much data you transact with your storage. For 24/7/365 always-on instances, cloud may very well not be a better deal than using with real servers.
The areas where Cloud can make your life easier (there is usually a cost for easy):
- Deploying new servers is very, very simple.
- Adding capacity on existing servers is as easy as paying for the option and rebooting.
- Disposing of servers is as simple as deleting them, no futzing about with resale/recycle/disposal.
In general, and you'll have to do the math yourself to see if this fits your use case, if your infrastructure is static and not likely to change much over the course of 12 months, cloud is probably not a good fit. If you need the capacity to add a bunch of resources right now rather than in three weeks, cloud is a better fit.