LearnGlossary

What is IOPS?

Updated 25 October 2026 · Published by Zoorik

IOPS, short for input/output operations per second, is how many reads and writes a disk handles each second. The IOPS meaning in storage is a rate of operations, not bytes. Every cloud disk has a limit.

Go over that limit, and the disk makes each operation wait longer.

IOPS in AWS and Azure

Amazon EBS counts up to 256 KiB as one operation on SSD volumes. For example:

  • One 1,024 KiB operation counts as 4.
  • Eight 32 KiB operations side by side on the disk merge into one, so they count as 1.
  • Eight random 32 KiB operations count as 8.
Amazon EBS counts each piece of up to 256 KiB as one operation Three examples of how Amazon EBS counts operations on SSD volumes, where up to 256 KiB counts as one. Each example shows what the app sends on top and what EBS counts below, with widths to scale. The first top bar is labelled the app sends. One operation of 1,024 KiB is split into 4 pieces of 256 KiB, so it counts as 4. Eight operations of 32 KiB each, side by side, are merged into one piece of 256 KiB, so they count as 1. Eight random operations of 32 KiB each are counted one by one, so they count as 8. Amazon EBS counts each piece of up to 256 KiB as one operation One operation1,024 KiBthe app sends256 KiB256 KiB256 KiB256 KiBsplitcounts as 4Eight, side by side32 KiB each256 KiBmergedcounts as 1Eight, random32 KiB eachone by onecounts as 8
AWS’s own examples for EBS SSD volumes: the top bar in each row is what the app sends, the bottom bar is what EBS counts, and widths are to scale. Where the random operations sit is an illustration.

Azure Premium SSD also counts up to 256 KiB as one operation. Each Azure virtual machine (VM) has its own IOPS limit, which can hold a disk below the disk’s own limit.

Why it matters for your bill

On some disks, the IOPS limit grows with size:

  • gp2 gets a baseline of 3 IOPS per GiB, from 100 to 16,000.
  • Premium SSD P10, at 128 GiB, gets 500 base IOPS, and P30, at 1,024 GiB, gets 5,000.

Say your app needs 5,000 IOPS. It holds 100 GiB, but on one Premium SSD disk you’d pay for 1,024 GiB.

On gp3 and Premium SSD v2, you set provisioned IOPS apart from size.

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.

The free assessment works out your own figure.

Read next: Azure disk IOPS vs throughput: what limits your disks

Sources: AWS, “Amazon EBS I/O characteristics and monitoring” (opens in a new tab); AWS, “Amazon EBS General Purpose SSD volumes” (opens in a new tab); Microsoft Learn, “Azure premium storage: Design for high performance” (opens in a new tab); Microsoft Learn, “Select a disk type for Azure IaaS VMs” (opens in a new tab).

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