CloudWatch Metric Guide
CPUUtilizationAmazon EC2 CloudWatch metric
CPUUtilization measures the percentage of allocated EC2 compute units (vCPUs) that are in use on the instance, as reported by the hypervisor.
What it measures
About CPUUtilization
CPUUtilization measures the percentage of allocated EC2 compute units (vCPUs) that are in use on the instance, as reported by the hypervisor.
| Namespace | AWS/EC2 |
| Metric name | CPUUtilization |
| Unit | Percent |
| AWS docs | Official Amazon EC2 metrics reference |
Why this metric matters
EC2 CPUUtilization is the most commonly monitored metric and the most commonly misconfigured alarm. The problem isn't knowing that high CPU is bad — it's knowing the difference between a legitimate utilization plateau and a runaway process. An instance running at 75% CPU doing useful work is healthy; an instance at 75% CPU because a cron job is stuck in an infinite loop is not.
For T3 and T3a instance families (burstable instances), CPU credits add a layer of complexity. The instance can burst above its baseline rate using accumulated credits. When credits are exhausted, CPU is hard-throttled to the baseline — an instance might drop from 80% to 20% effective CPU capacity instantly, causing severe application latency degradation without the CPUUtilization metric showing an obvious anomaly.
Recommended alarm threshold for CPUUtilization
Recommended threshold
> 80% for 15 consecutive minutes
A 15-minute sustained evaluation period (Nuberio recommendation) avoids alarming on brief CPU spikes caused by deployment, scheduled tasks, or garbage collection. For T-series burstable instances, add a separate alarm on CPUCreditBalance < 10 to catch credit exhaustion before the hard throttle takes effect. The 80% threshold balances alarm sensitivity against false positive rate for general workloads.
Is your CPUUtilization alarm already set up correctly?
The free Nuberio Audit scans your CloudWatch setup and flags missing or misconfigured alarms — including CPUUtilization — in 5 minutes.
Common failures that show up in CPUUtilization
When CPUUtilization reaches an alarm threshold, these are the most common root causes — in order of how often Nuberio sees them across customer AWS accounts.
Runaway process — a background job, cron task, or zombie process consumes CPU indefinitely without completing
Missing database index — a slow query forces the application to do CPU-intensive table scans rather than index lookups
Sudden traffic spike — application receives a volume of requests beyond its designed capacity, all of which require CPU-bound processing
CPU credit exhaustion on T-series instances — burstable instance runs above baseline for too long, exhausts credits, and gets throttled to baseline rate
Cryptographic operations under load — TLS termination, password hashing, or encryption operations consume more CPU than expected at scale
How the Nuberio Audit checks CPUUtilization
The free Audit scans every Amazon EC2 resource in your account and checks whether a CPUUtilization alarm exists, whether its threshold and evaluation period are configured sensibly, and flags it if it's missing entirely. Every finding comes with the exact CLI command to fix it — read-only access, no credit card, results in about 5 minutes.
Nuberio Audit
Scans your CloudWatch setup for missing or misconfigured CPUUtilization alarms. Free, 5-minute read-only scan.
Related Amazon EC2 metrics
CPUUtilization rarely fails in isolation. These metrics tend to correlate — monitor them together for complete Amazon EC2 coverage.
FAQ
Frequently asked questions about CPUUtilization
Common questions about setting up CloudWatch alarms for CPUUtilization in Amazon EC2.
What is the recommended CloudWatch alarm threshold for CPUUtilization?+
> 80% for 15 consecutive minutes. A 15-minute sustained evaluation period (Nuberio recommendation) avoids alarming on brief CPU spikes caused by deployment, scheduled tasks, or garbage collection. For T-series burstable instances, add a separate alarm on CPUCreditBalance < 10 to catch credit exhaustion before the hard throttle takes effect. The 80% threshold balances alarm sensitivity against false positive rate for general workloads.
Which CloudWatch namespace does CPUUtilization belong to?+
CPUUtilization is published in the AWS/EC2 namespace with a unit of Percent. You can find it in the CloudWatch console under "Metrics" → "AWS/EC2". See the Amazon EC2 CloudWatch metrics reference in the AWS documentation.
Does Nuberio automatically create CloudWatch alarms for CPUUtilization?+
No — the free Nuberio Audit does not create alarms for you. It scans your CloudWatch setup and tells you which Amazon EC2 resources are missing a CPUUtilization alarm, then gives you the exact CLI command to create it yourself.
Can I use Nuberio without already having a CPUUtilization alarm set up?+
Yes. The free Audit works whether or not you have any CPUUtilization alarm configured — it reads the resource directly from CloudWatch and tells you which resources need one, plus the copy-paste AWS CLI command to create it.
This page is part of the CloudWatch metric guide — thresholds and debugging guidance for every metric across RDS, Lambda, ECS, ALB, EC2, DynamoDB, SQS, API Gateway, S3, CloudFront, ElastiCache, and EKS. To find which Amazon EC2 alarms your account is missing — including CPUUtilization — run the free CloudWatch alarm audit. The scan takes under 5 minutes and requires no account.