Cloud cost
Rightsizing
Matching a resource's provisioned size to the usage you observe, not to the peak it was first sized for.
Last updated
Definition
Rightsizing compares what an instance, volume, or database is provisioned for with what it uses. You measure CPU, memory, IOPS, and throughput over a representative window. Then you resize down to match, or occasionally up. Most fleets carry real oversizing. Teams size instances once, for a traffic peak or a worst-case estimate, and rarely revisit them.
Rightsizing is a recurring practice, not a one-time project. Utilization drifts as code, traffic, and dependencies change. A resource that was right six months ago can be oversized today.
Where it shows up
Rightsizing draws on a resource's utilization metrics. These are CPU, memory, IOPS, or throughput, tracked over a representative window. You find them in a monitoring console or in the provider's recommendation tool, such as AWS Compute Optimizer. The provisioned size sits on the same resource record as the observed usage that the recommendation compares it against.
What makes it expensive
Teams size an instance once for a traffic peak and never look again. The peak passes, the traffic settles, and the dependencies change. The instance stays the size somebody guessed on launch day. The utilization data was there the whole time. Nothing ever prompts anyone to open it.
Related
More in Cloud cost
- Committed use discount (CUD)
- Reserved instance (RI)
- Savings plan (SP)
- On-demand vs. spot instances
- Data egress
- Amortized, blended, and unblended cost
- Billed vs. effective vs. list vs. contracted cost
- Idle and orphaned resources
- Storage class
- Lifecycle policy
- Incremental snapshot
- Allocatable capacity
- Requests vs. limits
- Cluster idle
- Workload idle
- Bin packing
- Cost allocation tags
- Tag coverage
- Unallocated spend
- Showback vs. chargeback
- Unit economics
- RI/SP coverage and utilization
- Observability tax
- Metric cardinality
- High-water-mark billing
- Log ingest vs. index
- Snowflake credit
- Auto-suspend / resume minimum
- BigQuery slot
- Bytes scanned & partition pruning
- Time Travel & Fail-safe
The meter you don't watch still grows.
Waste rarely hides in the service you check every week. CostMon watches every meter on your stack, including the ones you forgot were running.