AWS m5zn.12xlargevsAWS m6a.12xlarge

m5zn.12xlarge pairs 48 vCPUs with 192GB of RAM at $3.9641/hr On-Demand (about $2854/mo at 24×7). m6a.12xlarge pairs 48 vCPUs with 192GB at $2.0736/hr (~$1493/mo). m6a.12xlarge is 48% cheaper per hour than m5zn.12xlarge ($1.8905/hr gap).

These are different generations of the same series. **m6a.12xlarge** is the newer generation, and AWS's pattern across generations is fairly consistent: ~10–15% better single-thread, 15–30% better multi-core, and similar or modestly higher per-hour pricing — so the price/performance per dollar usually improves with each generation. **m5zn.12xlarge** is still available and still works (AWS doesn't retire instance types quickly), but for new workloads the newer generation is typically the better default unless you have a specific reason to pin to the older AMI or there's a meaningful regional pricing advantage today.

On raw price-per-performance, the two are m6a.12xlarge delivers ~407% more single-thread Sysbench score per dollar (388 vs 1967 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 (56947 vs 109113) are what to weigh. Spot pricing flips many of these comparisons — when m5zn.12xlarge drops to $1.2822/hr and m6a.12xlarge drops to $0.9616/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick m5zn.12xlarge when your workload is closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). Pick m6a.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.