Updated 25 October 2026 · Published by Zoorik
Rightsizing in cloud cost optimization means matching a resource’s size to what it needs, based on measured use. It applies to virtual machines (VMs), disks and databases. You change the size, type or count, or shut down what sits idle.
Provisioned vs used storage
Right sizing cloud storage compares the size you provisioned with the data on it. Azure managed disks and Amazon EBS volumes bill for the provisioned size.
Take Microsoft’s example:
- A 1 TiB Standard SSD holds 120 GiB but bills for all 1 TiB (the E30 tier).
- Its snapshots bill only for the 120 GiB used.
Rightsizing in AWS and Azure
- In AWS, the Well-Architected Framework says to right size instances whose peak CPU and memory stay under 40% for four weeks.
- AWS Compute Optimizer and AWS Trusted Advisor give rightsizing advice.
- For rightsizing in Azure, Azure Advisor suggests a cheaper VM size that fits the current load. It reads CPU, memory and outbound network use over 7 days by default, or up to 90.
Why it matters for your bill
- You pay for what you provision, busy or idle.
- Amoeba moves a VM’s data disks onto one pool sized to your data, then rightsizes it autonomously. It works on Azure managed disks and Amazon EBS volumes, on Windows and Linux VMs.
- Coral rebalances CPU and memory requests on AKS and EKS to match real use. The same pods fit on fewer nodes, and Coral drains spare ones so your autoscaler can remove them.
- The free assessment works out your own figure.
Read next: Kubernetes pod rebalancing
Sources: AWS, “COST06-BP03 Select resource type, size, and number automatically based on metrics” (opens in a new tab); Microsoft Learn, “Optimize virtual machine (VM) or virtual machine scale set (VMSS) spend by resizing or shutting down underutilized instances” (opens in a new tab); Microsoft Learn, “Understand Azure Disk Storage billing” (opens in a new tab); AWS, “Amazon EBS pricing” (opens in a new tab).