How Enterprises are Taming Runaway Cloud Expenses by Rightsizing AWS Instances

Rightsizing Amazon Web Services (AWS) instances involves matching instance sizes and types to your workload capacity and performance requirements to the least cost possible. Another definition is the process of examining your deployed AWS instances and identifying opportunities to downsize or eliminate without degrading capacity.

Rightsizing is a critical ingredient of your AWS cost optimization efforts. However, many organizations ignore this practice when they first move to AWS. Often, such organizations prioritize performance and speed over cost. This eventually leads to a lot of unused resources and wasted spend. 

The first step toward rightsizing is to analyze and monitor your organization's current use of services. This gives you insights into usage patterns and instance performance. To gather enough data, you must observe performance for 14 to 30 days to capture workload and business peak. 

Amazon RDS and Amazon EC2 are typically two of the top cost contributors to your AWS bill. Here are some tips to help you rightsize your RDS DB instances and EC2 instances. 

Rightsize Using Performance Data

Start by analyzing your EC2 instances' performance data. Identify any instances that are idle and underutilized. Look out for memory and CPU usage. Next, pick out instances with maximum CPU usage and less than 40 percent memory usage. These instances present your organization with the best chance to rightsize and cut costs. 

Rightsize Based on Usage Needs

Review Amazon Cloudwatch metrics to identify usage patterns and needs that enable you to take advantage of rightsizing opportunities. 

  • Steady State: In the steady state, the load remains at a constant level for some time. It is even possible to forecast the compute load at any one time. For this type of usage pattern, consider Reserved Instances. They can yield significant savings. 
  • Variable and predictable: For such instances, the load varies over time but on a predictable schedule. AWS Auto Scaling is ideal for applications that exhibit stable demand patterns weekly, daily, or hourly usage variability. You can use AWS Auto Scaling to scale EC2 capacity whenever there is a spike or fluctuation in traffic. 
  • Dev/test/production: Turn off production, testing, and development environments in the evening since organizations usually use them during business hours. 
  • Temporary: Do you have temporary workloads with flexible starting times that you can interrupt? Avoid using an on-demand instance. Instead, place a bid on an Amazon EC2 Spot Instance.  

Rightsize by Turning Off Idle Instances

Turning off idle AWS instances is one of the easiest ways to cut down on operational costs. If you have instances that have been idle for more than a week, you should stop them. Before terminating an instance, consider the following:

  • Who is the owner of the instance?
  • What is the impact of terminating the instance?
  • How difficult would it be to re-create the instance if it were necessary to restore it?

Rightsize by Selecting the Right Instance Family

Organizations can rightsize instances by moving them to a different model within the same family. Alternatively, you can move them to another instance family. 

If you are moving instances within the same family, only consider vCPU, network throughput, ephemeral storage, and memory. Are you migrating to a different family? Make sure the current instance type and the new one are compatible with the platform, network, and virtualization type. 

  • Virtualization type: Instances must have the same platform (EC2-VPC versus EC2-Classic) and virtualization type (HVM versus PV AMI). 
  • Network: You must launch some instances in a VPC (virtual private cloud) since EC2-Classic does not support them. 
  • Platform: If the current instance supports 32-bit AMIs, you should select a new instance type that supports 32-bit AMIs. 

Rightsize Your Database Instances

It is possible to scale database instances by adjusting to compute power or memory. Consider the following when scaling a database instance:

Decouple instance type and storage. Scaling your database instance does not affect storage. 

It is possible to separately modify your RDS DB instance and increase allocated space or improve performance by changing storage type. For example, you can go from a General Purpose SSD to a Provisioned IOPS SSD.  

Before scaling, ensure you have the right licensing for commercial engines, such as Oracle and SQL Server. This is particularly important if you BYOL (Bring Your Own License).

Decide on when to apply the change. You can apply it immediately or wait for the maintenance window specified for the instance. 


Rightsizing is one of the best ways to bring cloud costs under control. You have to analyze instance performance and usage patterns and needs continuously. After that, turn off idle instances and rightsize any instances that are either poorly matched to the workloads or overprovisioned. 

Rightsizing is an ongoing process. Resource needs are constantly changing, and you need to achieve cost optimization. Make rightsizing a process that is as hurdle-free as possible. Third-party AWS tools, such as nOps, will simplify resource analysis and monitoring.