Is the AWS Pricing Calculator Trustworthy?

You should definitely review your client's current Azure bill in detail. Look for overspending—like VMs that are running but not being utilized or storage that isn't attached to any servers. If you find areas where they can cut costs in Azure, that’s the first step. Then, take the relevant parts of the Azure bill and match them to the AWS pricing to get a more accurate comparison. You might find that the prices end up being fairly close.

AWS and Azure pricing for similar services are often comparable, so don't expect huge savings just from switching platforms. Instead, focus on optimizing and possibly rearchitecting resources in Azure. Sometimes, just improving the architecture can lead to lower costs regardless of the cloud provider.

It's not that the calculator is unreliable, but you need to ensure you're considering all the costs associated with your architecture. For example, if you're estimating for an EC2 instance, remember to factor in costs for EBS storage, public IP addresses, and data transfer rates. A lot of users forget to add EBS to their estimates because it's not very visible in the calculations.

The AWS Pricing Calculator itself is generally reliable. However, a lot of users run into hidden costs that aren't obvious until you start using AWS for real workloads. While your colleague may be mistaken about the calculator being unreliable, they're correct that there could be extra costs. It's a good idea to budget an additional 20-40% over the obvious components you include, like compute and storage. If you share what you've priced out, we could help identify any potential missing elements.