r5b.4xlarge

Analysis

The r5b.4xlarge is a memory optimized instance in the r5b series with 16 vCPUs and 128 GiB of memory on Intel Xeon Platinum 8259 (Cascade Lake) (up to 3.1 GHz), which makes it memory-heavy at 8 GiB of memory per vCPU.

Within the same generation and size, the r5a.4xlarge on AMD EPYC 7571 costs $0.9040/hour, 24% less ($210 a month). The other variants are the r5.4xlarge at $1.01, the r5ad.4xlarge at $1.05 and the r5d.4xlarge at $1.15.

Running it in N. Virginia instead of São Paulo saves $514 a month per instance: $1.19/hour against $1.90/hour, a 59% spread. It is not offered in Mumbai, so plan around that if you need a presence there.

On demand it costs $1.19/hour in US East (N. Virginia), $870 a month if left running, which puts it mid-table for memory optimized types at the 40th percentile per vCPU ($0.0745 per vCPU-hour) and the 56th percentile per GiB ($0.00931 per GiB-hour).

Looking beyond its own line, 17 of 42 current types with 16 vCPUs and similar memory are cheaper. The cheapest of those is the r6g.4xlarge on AWS Graviton2 at $0.8064/hour.

It is size 4 of 8 in the r5b series. Stepping up to the r5b.8xlarge gives 32 vCPUs and 256 GiB for $870 more a month. Dropping to the r5b.2xlarge saves $435 a month.