Updated 26 October 2026 · Published by Zoorik
AWS instance families are sets of EC2 instance types that differ only in size. An EC2 instance is an AWS server, usually a virtual machine (VM). Most families keep the same memory per virtual CPU (vCPU) at every size, except the burstable T families.
AWS instance family vs type
The instance type is the full name, such as c7gn.xlarge. An instance family in AWS is the part before the period. AWS’s example has four parts:
- c is the compute optimized series.
- 7 is the generation.
- gn holds the options: g for Arm-based Graviton processors, n for network and EBS-optimized.
- xlarge is the size.
Three EC2 instance families at one size
At the large size, each has 2 vCPUs but different memory:
- c7i.large, compute optimized: 4 GiB
- m7i.large, general purpose: 8 GiB
- r7i.large, memory optimized: 16 GiB
Why it matters for your cloud cost
If a family doesn’t match your pods’ requests, one resource runs out first. Part of the other sits idle on every node.
Say each pod requests 0.5 vCPU and 4 GiB. This illustration ignores what a node keeps for the system.
- An m7i.xlarge has 4 vCPUs and 16 GiB. Memory fills after 4 pods, so 2 vCPUs sit idle.
- An r7i.xlarge has 4 vCPUs and 32 GiB. It fits 8 pods exactly.
So 8 pods need two m7i.xlarge nodes or one r7i.xlarge. Compare the price per pod before you change a node group’s instance type.
The free assessment works out what your clusters and disks could save.
Read next: How to change an EKS node group instance type
Sources: Amazon Web Services, “Amazon EC2 instance type naming conventions” (opens in a new tab); Amazon Web Services, “Specifications for Amazon EC2 general purpose instances” (opens in a new tab); Amazon Web Services, “Specifications for Amazon EC2 compute optimized instances” (opens in a new tab); Amazon Web Services, “Specifications for Amazon EC2 memory optimized instances” (opens in a new tab).