AWS c5ad.8xlargevsAWS c5ad.xlarge

c5ad.8xlarge pairs 32 vCPUs with 64GB of RAM at $1.3760/hr On-Demand (about $991/mo at 24×7). c5ad.xlarge pairs 4 vCPUs with 8GB at $0.1720/hr (~$124/mo). c5ad.xlarge is 87% cheaper per hour than c5ad.8xlarge ($1.2040/hr gap).

Because both instances are in the **c5ad family**, the only thing that changes between them is sizing — same silicon, same architecture (AMD EPYC (x86_64)), same burstable/sustained behavior. The choice is purely about how much capacity you actually need: c5ad.8xlarge gives you 32 vCPUs and 64GB of RAM, c5ad.xlarge gives you 4 vCPUs and 8GB. 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 c5ad.xlarge delivers ~710% more single-thread Sysbench score per dollar (1176 vs 9529 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 (27368 vs 3454) are what to weigh. Spot pricing flips many of these comparisons — when c5ad.8xlarge drops to $0.6352/hr and c5ad.xlarge drops to $0.0743/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick c5ad.8xlarge when your workload is closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). Pick c5ad.xlarge 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.