How to read CPU usage
What CPU percentages mean and when to worry.
CPU usage is the share of processing capacity in use over a short time.
| Reading | Usually means |
|---|---|
| 0–20% | Idle or light work |
| 20–70% | Normal active use |
| 90–100% sustained | A heavy task is running; the PC may feel slow |
Brief spikes to 100% when opening an app are normal. If usage stays high while you are idle, open Task Manager’s Processes tab and sort by CPU to find the cause. See CPU and RAM monitoring.
Published 2026-10-14