Cost is what you pay to use cloud resources and services. Treat it as a fourth pillar alongside compute, networking, and storage: an application that works well still needs a bill you can live with. An accidentally oversized or forgotten VM can be expensive, but surprise bills are not inevitable. section 1.4 section 3.4.2
Cloud pricing takes some work to estimate because charges can depend on minutes of compute or individual service features. Start with a workload and its expected usage, then add up the services it needs. An image-resizing application handling 100,000 email attachments, 100,000 Function executions of 400 milliseconds each, and up to 1,000 GB of image storage has an illustrative estimate of $36.94 per month—not a price promise for every application. section 2.3.5
Table 2.1 Monthly cost of the image-resizing application
| Service type |
Region |
Description |
Estimated monthly cost |
Estimated up-front cost |
| Azure Logic Apps |
Australia East |
100,000 action executions x 1 day(s), 100,000 standard connector executions x 1 day(s) |
$15.80 |
$0.00 |
| Azure Functions |
Australia East |
Consumption tier, 512 MB memory, 400 ms execution time, 100,000 executions/month |
$0.00 |
$0.00 |
| Azure Storage accounts |
Australia East |
Block Blob Storage, Standard, general purpose V2, LRS redundancy, Hot access tier, 1,000 GB capacity |
$21.14 |
$0.00 |
| Total |
$36.94 |
$0.00 |
The monthly estimate breaks that image-resizing workload into Logic Apps ($15.80), Azure Functions ($0.00), and Blob Storage ($21.14), showing which service contributes to the $36.94 total under the stated assumptions. section 2.3.5
For a virtual machine, match the payment choice to how you use it:
- Enable auto shutdown if it need not run all day; idle minutes still cost money. section 3.4.2
- Consider Azure Spot Instances for development or other interruptible work, but expect that Azure can evict the VM. section 3.4.2
- Consider reserved instances when you can commit to one to three years of VM use. Before creating any VM, check the price shown by the wizard—an unintended larger size can raise the bill. section 3.4.2
Cost also belongs in architecture decisions. Azure SQL DB may cost more than Azure Database for MySQL, particularly at higher performance tiers, so weigh price against performance and security needs. In Azure Cosmos DB, autoscaling can make costs less predictable during demand spikes; multi-region replication adds storage and request-unit charges. Scale is useful, but it is not free. section 10.3.4 section 11.1.3
