AWS c6i vs c6g: Intel vs Graviton — Price, Performance & Migration Guide

Overview: What's the Difference?

Both families are compute-optimized — they offer a high ratio of vCPUs to memory (2 GiB per vCPU) and are designed for CPU-intensive workloads like batch processing, scientific computing, gaming servers, and high-performance web serving.

The fundamental difference is the processor architecture:

• c6i — Intel Xeon Scalable 8375C (Ice Lake), x86_64 architecture, 3.5 GHz all-core turbo
• c6g — AWS Graviton2, ARM64 (aarch64) architecture, custom Neoverse N1 cores

This architecture difference drives everything else: pricing, binary compatibility, and performance characteristics.

Specs Comparison

Pricing Comparison by Size

c6g is consistently ~20% cheaper than c6i at every size. Here's the On-Demand pricing in us-east-1:

At scale, these savings are significant. A fleet of 10 c6g.4xlarge instances saves nearly $12,000/year compared to c6i.4xlarge — with no change in capacity.

Benchmark Comparison

We compared c6i.4xlarge and c6g.4xlarge (both 16 vCPU, 32 GiB) across standard compute benchmarks:

See live benchmark data: c6i.4xlarge benchmarks | c6g.4xlarge benchmarks

When c6i Wins

Choose c6i (Intel) when architecture compatibility outweighs cost savings:

• x86 binary dependencies — If your application relies on precompiled x86 binaries with no ARM64 builds (legacy vendor software, certain security agents, specialized tools)
• AVX-512 workloads — Scientific computing, financial modeling, or machine learning inference that uses Intel's AVX-512 SIMD instructions for vectorized math
• x86-only container images — If your CI/CD pipeline or third-party images don't support multi-arch builds and you can't rebuild them
• Windows workloads — Windows on EC2 runs on x86 instances; Graviton instances only support Linux
• Maximum single-core performance — The ~5% single-core advantage matters for latency-sensitive workloads where every microsecond counts

When c6g Wins

Choose c6g (Graviton) when cost efficiency is the priority and your software runs on ARM:

• Cost-sensitive production workloads — The 20% per-hour savings adds up fast. For always-on production fleets, c6g pays for itself immediately
• Containerized applications — If you're running Docker/Kubernetes with multi-arch images, switching to c6g is a one-line change in your deployment config
• Web serving and APIs — Nginx, Node.js, Python Flask/Django, Ruby on Rails, Go HTTP servers — all run identically on ARM64 with zero code changes
• Interpreted language workloads — Python, Ruby, Node.js, PHP, and Java (JVM) don't care about the CPU architecture — the runtime handles it
• Open-source stacks — PostgreSQL, Redis, Elasticsearch, Kafka — the entire open-source data stack has native ARM64 support
• Auto-scaling groups — When running dozens or hundreds of instances, the 20% savings per instance compounds to tens of thousands of dollars annually

Migration Checklist: c6i to c6g

Follow this checklist to migrate from c6i (Intel) to c6g (Graviton) with confidence:

1. Audit all binaries — List every executable and shared library on your instance. Run file /usr/bin/* to check architectures. Anything showing “x86-64” needs an ARM64 equivalent.
2. Check third-party agents — Verify ARM64 support for monitoring (Datadog, New Relic), security (CrowdStrike), and any vendor agents. This is the #1 blocker.
3. Build multi-arch Docker images — Update your Dockerfile and CI pipeline to use docker buildx build --platform linux/amd64,linux/arm64. Test images on both architectures.
4. Validate ARM64 AMIs — If you use custom AMIs, rebuild them for ARM64. AWS Marketplace AMIs usually have ARM64 variants — check availability.
5. Test compiled dependencies — If your app uses native C extensions (Node.js native modules, Python C extensions), verify they compile and pass tests on ARM64.
6. Run load tests — Deploy a c6g instance in staging alongside c6i. Run identical load tests and compare throughput, latency, and error rates.
7. Canary deploy to production — Route 5–10% of production traffic to c6g instances. Monitor for 1–2 weeks before scaling up.
8. Update IaC — Change instance types in Terraform, CloudFormation, or CDK. Update launch templates and Auto Scaling groups.

Frequently Asked Questions

How much cheaper is c6g than c6i?

c6g is approximately 20% cheaper than c6i at every instance size. At the 4xlarge size, this translates to saving $0.136/hr or roughly $97.92/month per instance ($1,175/year). For a fleet of 10 instances, that's nearly $12,000/year in savings.

Is c6g faster than c6i?

In raw CPU benchmarks, c6i (Intel) scores about 5% higher in single-core and 2% higher in multi-core tests. However, c6g costs 20% less, so the price-performance ratio favors c6g by ~18%. For most workloads, c6g delivers more value per dollar spent.

Can I run x86 containers on c6g?

No. c6g uses the ARM64 architecture and cannot run x86/amd64 container images. You need either ARM64-native images or multi-architecture images. Most official Docker images (node, python, nginx, postgres) already publish multi-arch manifests. For your own images, use docker buildx to build for both platforms from a single Dockerfile.