AWS m8i.24xlargevsAWS m8i-flex.12xlarge

m8i.24xlarge pairs 96 vCPUs with 384GB of RAM at $5.0803/hr On-Demand (about $3658/mo at 24×7). m8i-flex.12xlarge pairs 48 vCPUs with 192GB at $2.4132/hr (~$1738/mo). m8i-flex.12xlarge is 52% cheaper per hour than m8i.24xlarge ($2.6671/hr gap).

Because both instances are in the **m8i 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: m8i.24xlarge gives you 96 vCPUs and 384GB of RAM, m8i-flex.12xlarge gives you 48 vCPUs and 192GB. 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 m8i.24xlarge and 3336/84174 for m8i-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 m8i.24xlarge when your workload is closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). Pick m8i-flex.12xlarge 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.