LearnGlossary

What is a node pool in Kubernetes?

Updated 25 October 2026 · Published by Zoorik

A node pool in Kubernetes is a group of nodes that share one configuration. On AKS each node is an Azure virtual machine (VM), and on EKS it’s an EC2 instance.

Node pool vs node group

  • An AKS node pool runs on a Virtual Machine Scale Set by default, with one VM size.
  • An AKS Virtual Machines node pool can mix up to five sizes from one family.
  • EKS’s closest match is the managed node group.
  • Each one runs on an EC2 Auto Scaling group and can list several instance types.
  • All its nodes are on-demand, or all are spot.

AKS system node pool vs user node pool

Every AKS cluster needs a system node pool for critical pods such as CoreDNS. By default, az aks create builds one with three nodes.

  • System nodes run Linux, with at least 4 virtual CPUs and 4 GB of memory.
  • Each system pool needs at least two nodes. Microsoft recommends three.
  • User pools run your apps on Linux or Windows, and can scale to zero.
A system pool keeps at least 2 nodes. A user pool can scale to 0. Illustration of one AKS cluster, an outer box labelled AKS cluster that holds two boxes side by side. The left box, System node pool, reads Runs critical pods such as CoreDNS, Linux, and Each node: at least 4 virtual CPUs and 4 GB. It holds 3 node boxes. The first 2 are solid, under a bracket labelled at least 2, and the third is dashed. A second bracket over all 3 reads 3 recommended. The right box, User node pool, reads Runs your apps, and Linux or Windows. Its 3 node boxes are all dashed, under a bracket labelled 0 or more nodes. A system pool keeps at least 2 nodes. A user pool can scale to 0. AKS clusterSystem node poolRuns critical pods such as CoreDNSLinuxEach node: at least 4 virtual CPUs and 4 GBnodenodenodeat least 23 recommendedUser node poolRuns your appsLinux or Windowsnodenodenode0 or more nodes
Illustration: a solid node must be there and a dashed node is optional, so a system pool never drops below 2 nodes while a user pool can scale to 0.

Why it matters for your bill

You pay for nodes, not pools. AKS bills nodes as standard VMs, and EKS adds no fee for managed node groups.

  • Each node’s price depends on its VM size or instance type, and whether it’s spot or on-demand.
  • Coral rebalances CPU and memory requests on AKS and EKS to match real use. It drains the spare nodes left over, so your autoscaler can remove them.
  • The free assessment works out your own figure.

Read next: Kubernetes node size best practices: large or small nodes

Sources: Microsoft Learn, “Azure Kubernetes Service (AKS) Core Concepts” (opens in a new tab); Microsoft Learn, “Use System Node Pools in Azure Kubernetes Service (AKS)” (opens in a new tab); Microsoft Learn, “Use Virtual Machines Node Pools in Azure Kubernetes Service (AKS)” (opens in a new tab); AWS, “Simplify node lifecycle with managed node groups” (opens in a new tab).

Find your own number

One line in your cloud console. One PDF report with your estimated saving at list price.

Estimate your saving

Talk to the builders

Thirty minutes with the people who build Coral.

Book a demo (opens in a new tab)

Or write to founders@zoorik.com