AWS d3en.4xlargevsAWS d3en.8xlarge

d3en.4xlarge pairs 16 vCPUs with 64GB of RAM at $2.1030/hr On-Demand (about $1514/mo at 24×7). d3en.8xlarge pairs 32 vCPUs with 128GB at $4.2058/hr (~$3028/mo). d3en.4xlarge is 100% cheaper per hour than d3en.8xlarge ($2.1028/hr gap).

Because both instances are in the **d3en 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: d3en.4xlarge gives you 16 vCPUs and 64GB of RAM, d3en.8xlarge gives you 32 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.

On raw price-per-performance, the two are d3en.4xlarge delivers ~93% more single-thread Sysbench score per dollar (503 vs 260 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 (13032 vs 27015) are what to weigh. Spot pricing flips many of these comparisons — when d3en.4xlarge drops to $0.5302/hr and d3en.8xlarge drops to $1.1379/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick d3en.4xlarge when your workload is closer to storage-optimized (HDD) (dense, sequential HDD storage — HDFS, MapReduce, log warehouses). Pick d3en.8xlarge when it's closer to storage-optimized (HDD) (dense, sequential HDD storage — HDFS, MapReduce, log warehouses). 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.