AWS i3en.3xlargevsAWS i3en.6xlarge

i3en.3xlarge pairs 12 vCPUs with 96GB of RAM at $1.3560/hr On-Demand (about $976/mo at 24×7). i3en.6xlarge pairs 24 vCPUs with 192GB at $2.7120/hr (~$1953/mo). i3en.3xlarge is 100% cheaper per hour than i3en.6xlarge ($1.3560/hr gap).

Because both instances are in the **i3en 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: i3en.3xlarge gives you 12 vCPUs and 96GB of RAM, i3en.6xlarge gives you 24 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.

On raw price-per-performance, the two are i3en.3xlarge delivers ~100% more single-thread Sysbench score per dollar (806 vs 403 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 (10075 vs 20250) are what to weigh. Spot pricing flips many of these comparisons — when i3en.3xlarge drops to $0.4664/hr and i3en.6xlarge drops to $1.0088/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick i3en.3xlarge when your workload is closer to storage-optimized (NVMe SSD) (I/O-bound work needing low-latency NVMe local storage — NoSQL, search). Pick i3en.6xlarge when it's closer to storage-optimized (NVMe SSD) (I/O-bound work needing low-latency NVMe local storage — NoSQL, search). 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.