Which EC2 Suffix Letters Indicate the CPU Manufacturer?

Amazon EC2 instance type names use specific suffix letters positioned immediately after the generation number to identify the underlying CPU manufacturer, with a indicating AMD, g indicating AWS Graviton, i indicating Intel, and m indicating Apple silicon Mac processors. Understanding these naming conventions allows cloud architects and developers to quickly determine processor architecture, optimize workload performance, and manage infrastructure costs without consulting external documentation. When no processor suffix letter is present in an older generation instance name, the instance defaults to using an Intel processor.

Anatomy of an Amazon EC2 Instance Name

An Amazon EC2 instance type name is composed of four distinct parts: the instance family, the instance generation, the processor or capability suffixes, and the instance size. These components are structured with the family, generation, and suffixes joined together before a period, followed by the size designation after the period.

For example, in the instance type name c7gn.xlarge:

  • Instance Family (c): Indicates a compute-optimized workload classification.
  • Instance Generation (7): Represents the seventh generation of this hardware family.
  • Attribute and Processor Suffixes (gn): Letters immediately following the generation number that specify the processor manufacturer (g for AWS Graviton) and additional capabilities (n for network optimization).
  • Instance Size (xlarge): Defines the allocation of vCPUs, memory, and bandwidth relative to the family baseline.

Suffix Letters for CPU Manufacturers

AWS assigns dedicated single-letter suffixes right after the generation number to denote the chipmaker powering the underlying host hardware.

i – Intel Processors

In newer EC2 generations (starting primarily with the 6th generation), the letter i explicitly designates instances powered by Intel Xeon Scalable processors. In generations 1 through 5, Intel was the default processor for most families, so no processor suffix was included (for example, m5.large runs on Intel). From the 6th generation onward, AWS introduced the i suffix to clearly distinguish Intel instances from AMD and AWS Graviton alternatives.

  • Examples: m6i.large, c7i.xlarge, r6in.2xlarge
  • Architecture: 64-bit x86 (x86_64)

a – AMD Processors

The letter a indicates that the instance is powered by AMD EPYC processors. AWS introduced AMD-based instances to offer an x86-compatible alternative that typically provides a lower cost per vCPU compared to equivalent Intel-based instances. Because both Intel and AMD share the x86_64 instruction set architecture, applications compiled for standard x86 Linux or Windows environments can generally transition between i and a instances without code modifications.

  • Examples: m5a.large, c6a.2xlarge, r7a.xlarge
  • Architecture: 64-bit x86 (x86_64)

g – AWS Graviton Processors

The letter g denotes instances powered by custom-built AWS Graviton processors, which are designed by AWS and Annapurna Labs using 64-bit Arm Neoverse cores. Graviton instances are engineered for high price-performance and energy efficiency across cloud-native workloads, containerized microservices, and open-source databases. Migrating from an i or a instance to a g instance requires software and container images to be compiled for the arm64 (aarch64) architecture.

  • Examples: m6g.large, c7g.xlarge, t4g.micro, r8g.medium
  • Architecture: 64-bit Arm (arm64)

m – Apple Silicon Processors (Mac Instances)

Within the mac instance family, the m suffix combined with the generation number indicates Apple silicon M-series processors as opposed to Intel-based Mac hardware. For instance, mac1.metal utilizes Intel Core i7 processors, whereas mac2.metal and mac2-m2pro.metal run on Apple-designed M1 and M2 system-on-chip (SoC) architectures.

  • Examples: mac2.metal, mac2-m2.metal, mac2-m2pro.metal
  • Architecture: 64-bit Arm (arm64 macOS)

Summary Comparison of CPU Suffixes

Suffix Letter CPU Manufacturer Processor Line Instruction Set Architecture Example Instance Types
i (or none) Intel Intel Xeon Scalable x86_64 m6i.xlarge, c7i.large, m5.large
a AMD AMD EPYC x86_64 m6a.xlarge, c7a.large, t3a.micro
g AWS AWS Graviton arm64 (aarch64) m7g.xlarge, c6g.large, t4g.small
m (in Mac family) Apple Apple Silicon (M-series) arm64 mac2-m2.metal, mac2-m1ultra.metal

Distinguishing CPU Suffixes from Capability Suffixes

Not every letter following the generation number refers to a CPU manufacturer. AWS frequently chains multiple suffix letters together, placing the CPU manufacturer letter first and capability modifiers immediately after it. Knowing the non-CPU capability letters prevents confusion when reading complex instance names:

  • d (Instance Store Volumes): Indicates that local NVMe-based SSD block storage is physically attached to the host server (for example, m6id.large is an Intel instance with local NVMe storage, and c6gd.xlarge is a Graviton instance with local NVMe storage).
  • n (Network and EBS Optimization): Signifies enhanced networking throughput and higher Amazon EBS bandwidth (for example, c6in.xlarge runs on an Intel CPU with up to 200 Gbps network performance).
  • e (Extra Capacity): Represents extra memory or storage capacity within a family (for example, r6ie.xlarge or i4g.large).
  • z (High Frequency): Denotes processors running at sustained high all-core turbo clock frequencies (for example, c7i-flex.large vs z1d.large or m5zn.large).
  • b (Block Storage Optimized): Indicates instances specifically tuned for high Amazon EBS performance (for example, r5b.xlarge).
  • flex (Flexible Compute): Appended with a hyphen (such as c7i-flex.large or m7i-flex.xlarge) to indicate instances designed to deliver baseline performance with the ability to scale up to full compute utilization for the majority of workloads.