Understanding and Predicting Azure Costs

• Unexpected Azure costs can occur because of complex billing metrics, service dependencies, and unpredictable application behavior.
• The number and variety of metrics makes it difficult to establish budgets and predict costs prior to going live.
• Microsoft provides estimation tools for approximating costs before deployment, but they should only be used for rough estimates.
• Customers should include contingency in budgets and plan for ongoing monitoring and adjustments to control costs.

Azure services employ a wide array of billing metrics that measure usage by various rates and capacities. Services may have cross-dependencies that result in additional costs that are not obvious until after the solution is deployed and in use. Microsoft provides tools for predicting Azure costs, but customers may incur unexpected charges due to usage patterns even when the tools are used. 

Many Billing Metrics, Even in Simple Solutions

Azure solutions that customers create, such as a Web application, typically consist of multiple Azure resources, such as VMs, databases, and networking elements. Each resource type has its own billing metrics, and most services use multiple metrics that fall into the following two categories: