AWS Cost Levers
AWS for Interviews: lesson 11 of 18
Right-size, scale, commit the floor, Spot the rest, watch the wires.
Lesson 11 of 18 · 6 min
AWS Cost Levers
Step 1 of 10
One service's day in two-hour blocks. Each bar is how many instances that block actually needs.
The Idea
Pull the levers in order. Switch off what idles and right-size: Compute Optimizer flags over-provisioned instances. Scale with demand. Commit the steady floor with Savings Plans or Reserved Instances. Put interruptible work on Spot — spare capacity at steep discounts that EC2 can reclaim with a two-minute notice. Then watch data transfer.
Real-World Example
A service needs three instances all day and nine at its peak. An Auto Scaling group follows the curve, a Savings Plan covers the three, peaks stay On-Demand, and the nightly batch runs on Spot, checkpointing so an interruption costs minutes, not the job.
The Tradeoff
A commitment only pays off on usage you keep, so commit to the floor you measured, not the peak you hope for. NAT gateways bill per GB processed; send S3 and DynamoDB traffic through gateway endpoints.
Hands-On
# illustrative — needs Compute Optimizer enabled and Cost Explorer access
aws compute-optimizer get-ec2-instance-recommendations \
--filters name=Finding,values=Overprovisioned
aws ce get-cost-and-usage \
--time-period Start=2026-09-01,End=2026-10-01 \
--granularity MONTHLY --metrics UnblendedCost \
--group-by Type=DIMENSION,Key=SERVICE
Your turn
Put the steps in the right order.
- Move interruptible batch work to Spot
- Commit to the steady baseline with a Savings Plan
- Scale the fleet with demand
- Turn off idle resources and right-size the rest
Mini quiz
1 / 3
Which workload suits Spot Instances?
Sources
- Amazon EC2 billing and purchasing options — Amazon EC2 User Guide
- Spot Instance interruption notices — Amazon EC2 User Guide
- Savings Plans types — Savings Plans User Guide
- Pricing for NAT gateways — Amazon VPC User Guide