How much does an idle c5.4xlarge cost on AWS?
A c5.4xlarge billed on-demand and left running around the clock costs about $496/mo at its cheapest listed region (us-east-1). Scheduling it off outside business hours cuts that to roughly $148/mo — a $349/mo saving.
Cheapest on-demand
$0.6800/hr
us-east-1
Running 24/7
$496/mo
730-hour month
Business-hours savings
$349/mo
70% off the 24/7 bill
Price by region
| Region | Hourly (on-demand) | Spot (typical) | ≈ Monthly (24/7) |
|---|---|---|---|
| us-east-1 Cheapest | $0.6800/hr | $0.2312/hr | ≈ $496/mo |
| us-east-2 | $0.6800/hr | $0.1904/hr | ≈ $496/mo |
| us-west-2 | $0.6800/hr | $0.2244/hr | ≈ $496/mo |
| ap-south-1 | $0.6800/hr | $0.1768/hr | ≈ $496/mo |
| eu-west-1 | $0.7680/hr | $0.3994/hr | ≈ $561/mo |
| eu-central-1 | $0.7760/hr | $0.1862/hr | ≈ $566/mo |
| ap-southeast-1 | $0.7840/hr | $0.2822/hr | ≈ $572/mo |
| ap-northeast-1 | $0.8560/hr | $0.2311/hr | ≈ $625/mo |
| ap-southeast-2 | $0.8880/hr | $0.2753/hr | ≈ $648/mo |
| sa-east-1 | $1.0480/hr | $0.1782/hr | ≈ $765/mo |
What a schedule saves
| Schedule | Monthly cost | Savings vs 24/7 |
|---|---|---|
| Running 24/7 | $496/mo | baseline |
| Weekdays only (off on weekends) | $355/mo | -$142/mo (29%) |
| Business hours only (10×5) | $148/mo | -$349/mo (70%) |
Assumes a 730-hour month at on-demand list price. Actual savings depend on when the instance is actually used.
About the c5 family
C5 is AWS's compute-optimized Intel family — a high vCPU-to-memory ratio built for CPU-bound work like batch processing, video encoding, and CI/CD build fleets. Build agents and load-test rigs are classic C5 tenants: they need real CPU during a run, then sit completely idle between runs. That gap between "when a build kicks off" and "when the box is provisioned" is one of the most common sources of pure waste we see in dev clouds.
Regional pricing varies: c5.4xlarge runs $0.6800/hr in us-east-1, the cheapest region priced here, versus $1.0480/hr in sa-east-1, the priciest — a 35% spread across regions for the identical instance type.
Common questions
How much does an idle c5.4xlarge cost per month?
At the cheapest listed region (us-east-1), a c5.4xlarge costs $0.6800/hr, or about $496/mo if it runs 24/7. That's the on-demand list price — an idle instance costs exactly the same as a busy one, since cloud billing doesn't know the difference.
How much can I save by scheduling it off outside work hours?
Restricting it to business hours only (10×5) saves about $349/mo (70%) versus running 24/7. A lighter schedule — on around the clock on weekdays, off on weekends — still saves about $142/mo (29%).
Should CI build agents run around the clock?
Almost never — build fleets have the burstiest usage profile in a dev cloud: real load during working-hours pushes, near-zero overnight and on weekends. Autoscaling helps, but a floor of always-on agents quietly becomes the dominant cost. Leasing agents up for the workday and letting them stop afterwards is usually the single biggest win on a c5 fleet.
Other c5 sizes
Stop paying for idle AWS servers
Idlefy runs a free audit of your fleet, then flips dev servers to stopped-by-default: lease one when you need it, and
when the lease ends it shuts itself off — stop, not terminate, persistent disks intact. Timers are set by your team, never
guessed, and Idlefy only manages instances tagged idlefy=enabled — on AWS that boundary is enforced by the IAM policy itself.
Prices are on-demand list price for Linux instances and exclude storage, network, data transfer, and any negotiated or volume discounts. Actual bills vary by usage and account-level pricing. Prices as of 2026-07-20. Spot figures are indicative — AWS values are derived from AWS's published typical savings vs on-demand for the region; GCP values are the listed Spot price. Spot capacity can be reclaimed by the provider. Stopping preserves EBS and persistent-disk volumes; data on local instance-store or local-SSD drives does not survive a stop.