5 AWS Cost Mistakes We See in Every Audit

1. Running dev and staging environments 24/7

Most teams spin up development and staging environments that mirror production — then leave them running around the clock. If your developers work 8 hours a day, those environments sit idle for the other 16.

The fix: Use Instance Scheduler or a simple Lambda function to stop non-production instances outside working hours. This alone typically saves 60–70% on dev environment costs.

2. Oversized RDS instances

When teams provision an RDS database, they often choose an instance class based on peak expected load rather than actual usage. We regularly find db.r5.xlarge instances running at 5–10% CPU utilisation.

The fix: Enable Performance Insights, monitor for two weeks, then right-size. Moving from r5.xlarge to r5.large halves your RDS spend with zero application changes.

3. No Reserved Instances or Savings Plans

On-Demand pricing is the most expensive way to run workloads on AWS. If you have predictable baseline compute, you are overpaying by 30–40%.

The fix: Start with a Compute Savings Plan for your baseline. Add Reserved Instances for databases and other steady-state workloads. Review quarterly.

4. Orphaned EBS volumes and snapshots

Every time a developer terminates an EC2 instance, the associated EBS volumes often survive. Over months, you accumulate gigabytes (sometimes terabytes) of storage nobody uses.

The fix: Run a monthly audit with AWS Cost Explorer or a script that identifies unattached volumes. Set up a CloudWatch alarm for volumes that stay unattached for more than 7 days.

5. Data transfer between Availability Zones

Architects correctly design for high availability across multiple AZs — but cross-AZ data transfer is not free. At £0.01/GB in each direction, a chatty microservices architecture can rack up hundreds of pounds per month in transfer charges.

The fix: Use VPC Endpoints for AWS service traffic, keep chatty services in the same AZ where possible, and compress payloads between services.

What to do next

If any of these sound familiar, you are not alone. We see these patterns in 9 out of 10 audits we conduct. The good news is that fixing them is straightforward — and the savings are usually significant enough to fund your next project.

Book a free Cloud Health Check and we will review your AWS bill, identify quick wins, and give you a prioritised action plan.