AWS r7i.largevsAWS r8i.large

r7i.large pairs 2 vCPUs with 16GB of RAM at $0.1323/hr On-Demand (about $95/mo at 24×7). r8i.large pairs 2 vCPUs with 16GB at $0.1389/hr (~$100/mo). r7i.large is 5% cheaper per hour than r8i.large ($0.0066/hr gap).

These are different generations of the same series. **r8i.large** 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. **r7i.large** 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 roughly tied on single-thread performance per dollar (24747 vs 23884 Sysbench 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 (3350 vs 3482) are what to weigh. Spot pricing flips many of these comparisons — when r7i.large drops to $0.0442/hr and r8i.large drops to $0.0437/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r7i.large when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r8i.large when it's closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). 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.