AWS c8i.24xlargevsAWS c8i-flex.12xlarge

c8i.24xlarge pairs 96 vCPUs with 192GB of RAM at $4.4981/hr On-Demand (about $3239/mo at 24×7). c8i-flex.12xlarge pairs 48 vCPUs with 96GB at $2.1365/hr (~$1538/mo). c8i-flex.12xlarge is 53% cheaper per hour than c8i.24xlarge ($2.3616/hr gap).

Because both instances are in the **c8i family**, the only thing that changes between them is sizing — same silicon, same architecture (Intel Xeon (x86_64)), same burstable/sustained behavior. The choice is purely about how much capacity you actually need: c8i.24xlarge gives you 96 vCPUs and 192GB of RAM, c8i-flex.12xlarge gives you 48 vCPUs and 96GB. 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.

Benchmark data for at least one of these instances is still being collected, so a direct performance-per-dollar comparison isn't possible yet. Sysbench scores are pending for c8i.24xlarge and 3322/84021 for c8i-flex.12xlarge. Check back as the benchmark queue completes — newer-generation instances typically score 10–30% higher on single-thread and 15–50% higher on multi-core vs the previous generation in the same series.

In practice, pick c8i.24xlarge when your workload is closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). Pick c8i-flex.12xlarge when it's closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). 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.