AWS r8g.largevsAWS r8g.medium

r8g.large pairs 2 vCPUs with 16GB of RAM at $0.1178/hr On-Demand (about $85/mo at 24×7). r8g.medium pairs 1 vCPUs with 8GB at $0.0589/hr (~$42/mo). r8g.medium is 50% cheaper per hour than r8g.large ($0.0589/hr gap).

Because both instances are in the **r8g family**, the only thing that changes between them is sizing — same silicon, same architecture (AWS Graviton (ARM64)), same burstable/sustained behavior. The choice is purely about how much capacity you actually need: r8g.large gives you 2 vCPUs and 16GB of RAM, r8g.medium gives you 1 vCPUs and 8GB. AWS scales pricing close to linearly within a family, so picking the right size is mostly about right-sizing your workload, not getting a better deal per vCPU.

On raw price-per-performance, the two are r8g.medium delivers ~93% more single-thread Sysbench score per dollar (28306 vs 54609 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 (6483 vs 3150) are what to weigh. Spot pricing flips many of these comparisons — when r8g.large drops to $0.0370/hr and r8g.medium drops to $0.0094/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r8g.large when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r8g.medium 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.