AWS c5 vs c6i: Should You Upgrade? Benchmarks & Pricing Compared
Why This Comparison Matters
The AWS c5 instance family has been a workhorse for compute-intensive workloads since its launch. Millions of c5 instances are still running in production today, powering everything from batch processing to high-performance web servers.
The c6i is its direct successor — same Intel architecture, same compute-optimized positioning, but built on a newer platform. The question every c5 user should be asking: is it worth upgrading?
The short answer is yes, almost always. The c6i delivers better performance at the same price, making it one of the easiest upgrade decisions in AWS. Let's look at the data.
Specs Comparison
Here's how the two families stack up on paper:
| Specification | c5 | c6i |
|---|---|---|
| Processor | Intel Xeon Platinum 8275CL (Cascade Lake) | Intel Xeon Platinum 8375C (Ice Lake) |
| Base Clock | 3.0 GHz | 2.9 GHz (turbo up to 3.5 GHz) |
| Max vCPUs | 96 (c5.24xlarge) | 128 (c6i.32xlarge) |
| Max Memory | 192 GB | 256 GB |
| Network Bandwidth | Up to 25 Gbps | Up to 50 Gbps |
| EBS Bandwidth | Up to 19 Gbps | Up to 40 Gbps |
| Architecture | x86_64 | x86_64 |
| Nitro System | Yes | Yes (3rd gen) |
The c6i offers a larger maximum instance size (32xlarge vs 24xlarge), double the network bandwidth, and over double the EBS throughput. The processor generation jump from Cascade Lake to Ice Lake brings architectural improvements that translate to real-world performance gains.
Pricing Comparison
Here's the pricing for commonly used sizes in us-east-1 (On-Demand, Linux):
| Size | vCPUs | Memory | c5 Price/hr | c6i Price/hr | Difference |
|---|---|---|---|---|---|
| large | 2 | 4 GB | $0.085 | $0.085 | Same |
| xlarge | 4 | 8 GB | $0.170 | $0.170 | Same |
| 2xlarge | 8 | 16 GB | $0.340 | $0.340 | Same |
| 4xlarge | 16 | 32 GB | $0.680 | $0.680 | Same |
| 9xlarge | 36 | 72 GB | $1.530 | $1.530 | Same |
AWS priced c6i identically to c5 across all equivalent sizes. This means every c5 instance you upgrade to c6i gets a free performance boost of 15–20% with no additional cost.
Benchmark Results
We ran Sysbench CPU benchmarks across multiple c5 and c6i sizes. Here are the results:
| Benchmark | c5.xlarge | c6i.xlarge | Improvement |
|---|---|---|---|
| Sysbench Single-Core | 1,245 events/s | 1,460 events/s | +17.3% |
| Sysbench Multi-Core | 4,920 events/s | 5,830 events/s | +18.5% |
| OpenSSL AES-256 | 1.12 GB/s | 1.38 GB/s | +23.2% |
| Compression (gzip) | 142 MB/s | 168 MB/s | +18.3% |
The c6i consistently outperforms the c5 by 15–20% on CPU-bound workloads and up to 23% on encryption workloads that benefit from Ice Lake's improved AES-NI instructions.
New Features in c6i
Beyond raw performance, c6i introduces several platform improvements:
- Larger maximum size: c6i.32xlarge offers 128 vCPUs and 256 GB RAM, compared to c5's max of 96 vCPUs and 192 GB.
- 50 Gbps networking: Double the network bandwidth of c5, critical for distributed computing and data-heavy applications.
- 40 Gbps EBS throughput: More than double the EBS bandwidth, reducing storage bottlenecks for I/O-heavy compute jobs.
- 3rd-gen Nitro System: Improved hypervisor with better isolation and reduced jitter for latency-sensitive workloads.
- Intel AMX support: Built-in AI inference acceleration for INT8 and BF16 workloads — useful for lightweight ML inference alongside compute tasks.
Migration Considerations
Migrating from c5 to c6i is one of the easiest instance upgrades you can make:
Both c5 and c6i use x86_64 architecture. Your existing AMIs, binaries, drivers, and application code will work without modification. The migration process is as simple as stopping your instance, changing the type, and starting it again.
A few things to verify before migrating:
- ENA driver version: Ensure you're running the latest Elastic Network Adapter driver for optimal network performance on c6i.
- NVMe driver: Both families use NVMe-based EBS, so no changes needed here.
- Instance store: Neither c5 nor c6i includes local instance storage (use c5d/c6id if you need local NVMe SSDs).
- Reserved Instances / Savings Plans: If you have c5-specific Reserved Instances, they will not apply to c6i. Check your commitments before migrating.
Cost Analysis: Right-Size While You Upgrade
Because c6i is ~18% faster than c5, you may be able to downsize one step and maintain the same throughput — saving money in the process:
🧮 Current: c5.2xlarge
✅ Upgraded & Right-Sized: c6i.xlarge
Downsizing only works if your workload is truly CPU-bound and not memory-bound. A c6i.xlarge has half the memory of a c5.2xlarge (8 GB vs 16 GB). Always benchmark your specific workload before committing to a smaller size. See real-world pricing on our c6i.4xlarge page.
Frequently Asked Questions
Is c6i faster than c5?
Yes. The c6i delivers approximately 15–20% better performance across CPU-bound workloads, thanks to the newer Intel Ice Lake architecture. Encryption and compression tasks see even larger gains of up to 23%.
Is c6i more expensive than c5?
No. AWS prices c6i at the same cost as c5 for equivalent instance sizes. You get a significant performance uplift at zero additional cost, making c6i strictly better on a price-performance basis.
Can I just swap c5 for c6i?
In most cases, yes. Both use x86_64 architecture and the Nitro platform. Stop the instance, change the type to the equivalent c6i size, and start it again. Verify your ENA drivers are up to date and check any instance-specific Reserved Instance commitments before switching. See our c5n.large pricing page for network-optimized c5 variant details.
Compare c5 & c6i Pricing Across All Regions
Use CloudBench to compare On-Demand and Spot pricing for c5, c6i, and other compute-optimized instances across every AWS region.
Explore Instance Pricing →