Instances›AWS EC2›c8i-flex›c8i-flex.16xlarge
Compute
vCPUs64
Memory128 GiB
Mem / vCPU2.00 GiB
ProcessorXeon Scalable
Clock speed3.9 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth20,000 Mbps
Throughput2500 MB/s
IOPS80,000
Networking
PerformanceUp to 30 Gigabit
Max ENIs16
IPv6Yes
GPUNone
Family sizes
c8i-flex.large2 vCPU · 4 GiB
c8i-flex.xlarge4 vCPU · 8 GiB
c8i-flex.2xlarge8 vCPU · 16 GiB
c8i-flex.4xlarge16 vCPU · 32 GiB
c8i-flex.8xlarge32 vCPU · 64 GiB
c8i-flex.12xlarge48 vCPU · 96 GiB
c8i-flex.16xlarge64 vCPU · 128 GiB
c8i-flex.16xlarge

The c8i-flex.16xlarge pairs 64 vCPU with 128 GiB of RAM, the 2.00 GiB-per-vCPU ratio that marks a compute-optimized instance. It runs on Intel Xeon Scalable (Granite Rapids) at 3.9 GHz, and AWS introduced it in October 2025. Spot's node ladder tops out below this size, so c8i-flex.16xlarge becomes 4 × ch.vs1.2xlarge (64 vCPU, 128 GiB combined), about 94% below the US East (N. Virginia) on-demand rate. Spot delivers compute as managed Kubernetes, so a node pool of that size is the native shape of the answer rather than a workaround — provided the workload scales horizontally.

Match qualityScale-out match

c8i-flex.16xlarge gives you 64 vCPU and 128 GiB in a single machine. The largest comparable Spot node, ch.vs1.2xlarge, is 16 vCPU and 32 GiB, so the equivalent here is 4 nodes rather than one.

Spot runs as managed Kubernetes, so a 4-node pool is the normal way to run things rather than a workaround. If your workload already sits behind a load balancer, a queue or a scheduler, it spreads across them without changes. If it needs all 64 cores and 128 GiB in one process, it does not.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$2.849$0.545$0.164
$2.685 savings
US Central, Chicagono AWS region$0.044
US Central, Dallasno AWS region$0.444
Hong Kong$0.164
Sydney, Australia$3.720$3.196$0.164
$3.556 savings
London, UK$3.385$1.109$0.524
$2.861 savings
US West, San Jose$3.553$1.382$0.008
$3.545 savings
US Central, Dallas 2no AWS region$0.488
US East, N. Virginia 2$2.849$0.545$0.648
$2.201 savings
When to use it
Good for
  • ●High-traffic web and API serving
  • ●Scientific modelling and simulation
  • ●Ad serving and real-time bidding
  • ●Workloads that fit inside 128 GiB of RAM
  • ●Parallel work that can occupy 64 vCPU
  • ●Network-heavy services — AWS rates this size at Up to 30 Gigabit
  • ●Anything that shards cleanly across 4 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●The working set needs more than 128 GiB of RAM
  • ●GPU or FPGA acceleration is needed
  • ●Memory-hungry applications. A memory-optimized family gives more RAM per dollar.
  • ●More than 2.00 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
  • ●The work is single-threaded. Most of these 64 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
$2,079/mo on AWS on-demand against $120/mo on Rackspace Spot for the 4-node equivalent — market-priced, not list-priced.
  • Spot sells spare capacity at market prices. It is the cheapest compute on the internet.
  • Prices are set by supply and demand. You pay what the market decides.
  • Compute is delivered as fully managed Kubernetes. All infrastructure is taken care of.
  • Egress costs $0.01/GB after the free allowance. AWS charges $0.09/GB.
Build your Cloudspace
Frequently asked questions