AWS c8i.32xlargevsAWS c8i-flex.16xlarge

c8i.32xlarge pairs 128 vCPUs with 256GB of RAM at $5.9974/hr On-Demand (about $4318/mo at 24×7). c8i-flex.16xlarge pairs 64 vCPUs with 128GB at $2.8486/hr (~$2051/mo). c8i-flex.16xlarge is 53% cheaper per hour than c8i.32xlarge ($3.1488/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.32xlarge gives you 128 vCPUs and 256GB of RAM, c8i-flex.16xlarge gives you 64 vCPUs and 128GB. 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.32xlarge and 3333/112233 for c8i-flex.16xlarge. 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.32xlarge when your workload is closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). Pick c8i-flex.16xlarge 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.