AWS r8i-flex.largevsAWS r8i.large

r8i-flex.large pairs 2 vCPUs with 16GB of RAM at $0.1320/hr On-Demand (about $95/mo at 24×7). r8i.large pairs 2 vCPUs with 16GB at $0.1389/hr (~$100/mo). r8i-flex.large is 5% cheaper per hour than r8i.large ($0.0069/hr gap).

r8i-flex.large (memory-optimized, Intel Xeon (x86_64)) and r8i.large (memory-optimized, Intel Xeon (x86_64)) target different workload shapes. The vCPU:RAM ratios are different (2:16 vs 2:16), and depending on the architectures involved you may also see meaningful single-thread performance and per-hour-cost differences. This kind of cross-category comparison is most useful when you're early in the design phase and not yet sure whether your workload is CPU-bound, memory-bound, or balanced — once that's clear, the right pick is usually obvious.

On raw price-per-performance, the two are r8i-flex.large delivers ~5% more single-thread Sysbench score per dollar (24983 vs 23884 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 (3464 vs 3482) are what to weigh. Spot pricing flips many of these comparisons — when r8i-flex.large drops to $0.0449/hr and r8i.large drops to $0.0444/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r8i-flex.large when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r8i.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.