AWS r6a.largevsAWS r6g.large

r6a.large pairs 2 vCPUs with 16GB of RAM at $0.1134/hr On-Demand (about $82/mo at 24×7). r6g.large pairs 2 vCPUs with 16GB at $0.1008/hr (~$73/mo). r6g.large is 11% cheaper per hour than r6a.large ($0.0126/hr gap).

Both are generation-6 memory-optimized instances, but they run on different silicon: **r6a.large** is AMD EPYC (x86_64), **r6g.large** is AWS Graviton (ARM64). AMD variants (suffix `a`) are typically 10% cheaper than Intel siblings at comparable single-thread performance. Graviton variants (suffix `g`) are usually 20–40% cheaper but require ARM64-compatible binaries — most modern Linux stacks are fine, but verify any compiled extensions, native modules, or third-party binaries before migrating. Same vCPU/RAM ratio, same network performance class, different processor.

On raw price-per-performance, the two are r6a.large delivers ~29% more single-thread Sysbench score per dollar (35847 vs 27798 points per $1/hr). That's the cleanest signal we have for "which one runs your workload faster per dollar," but it only matters if your workload is single-thread-bound; for parallel workloads the multi-core scores (4501 vs 5323) are what to weigh. Spot pricing flips many of these comparisons — when r6a.large drops to $0.0445/hr and r6g.large drops to $0.0406/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r6a.large when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r6g.large when it's closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). When neither side is obviously right, the cheaper hourly rate usually wins for fault-tolerant batch workloads, while the higher single-core score usually wins for latency-sensitive web traffic. The regional pricing tables linked from each instance page below show where each is currently cheapest — sometimes a >20% regional gap flips the comparison entirely.