AWS m7i.4xlargevsAWS m7i-flex.4xlarge

m7i.4xlarge pairs 16 vCPUs with 64GB of RAM at $0.8064/hr On-Demand (about $581/mo at 24×7). m7i-flex.4xlarge pairs 16 vCPUs with 64GB at $0.7661/hr (~$552/mo). m7i-flex.4xlarge is 5% cheaper per hour than m7i.4xlarge ($0.0403/hr gap).

m7i.4xlarge (general-purpose, Intel Xeon (x86_64)) and m7i-flex.4xlarge (general-purpose, Intel Xeon (x86_64)) target different workload shapes. The vCPU:RAM ratios are different (16:64 vs 16:64), 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 m7i-flex.4xlarge delivers ~8% more single-thread Sysbench score per dollar (3977 vs 4288 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 (26172 vs 36061) are what to weigh. Spot pricing flips many of these comparisons — when m7i.4xlarge drops to $0.3402/hr and m7i-flex.4xlarge drops to $0.2974/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick m7i.4xlarge when your workload is closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). Pick m7i-flex.4xlarge when it's closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). 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.