The single highest-impact easy win in most AWS accounts is rightsizing EC2 instances
Not reserved instances. Not spot instances. Not exotic optimization strategies. Just running the right size instance for the actual workload
It sounds obvious. The gap between what sounds obvious and what actually gets done is where most of the money is
Here's what I find when I look at EC2 utilization across a typical account
A significant portion of instances running at under 20 percent CPU on average. Some of them under 10 percent. Instances that were provisioned for a traffic spike that never came, or for a peak load that happened once six months ago, or because the engineer who set them up defaulted to a size that felt comfortable
The memory story is usually worse. CPU is visible. Memory utilization is often not even being tracked. Teams that don't have proper monitoring genuinely don't know how much memory their services are using. They sized for worst case and never looked again
AWS provides Compute Optimizer for this. It analyzes your actual utilization over time and recommends the right instance type. It's not perfect but it's a real starting point
The process is straightforward
Turn on Compute Optimizer if you haven't already. Let it run for at least two weeks to get meaningful data. Look at the recommendations. For each one, check the recommendation against what you know about the workload. Is there a reason the instance needs to be larger than utilization suggests? Scheduled batch jobs? Burst traffic patterns?
For everything where the recommendation makes sense: test in staging, deploy with a rollback plan, monitor for 48 hours
Most rightsizing changes are safe. Some need care. The ones that need care are almost always the ones where utilization spikes unpredictably
The savings vary but in accounts that haven't been looked at in a while, 20 to 30 percent reduction in compute costs from rightsizing alone is not unusual
It's the first place I look
Every time
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