Costs are central to designing for the cloud. Selecting the most appropriate options from a wide variety of tunable parameters available for each of the services can make this a challenging task. Typically, if you understand the cost for your compute nodes and database services well, then you would have largely accounted for a big chunk of your expected bill. Using an 80:20 principle can help get you to ballpark cost estimates quickly.

Most cloud service providers make online calculators available to arrive at the ballpark figures for your infrastructure. The following is a sample screenshot for provisioning AWS EC2 instances (compute nodes) in a calculator provided by Amazon. The left margin contains links for estimating the costs of AWS services that you plan to provision for your application:

The following figure is a sample screenshot of the AWS calculator's monthly bill tab. This tab presents the total costs you can expect on a monthly basis. These...