EC2 instances are paid by the amount of time they are turned on. 1-hour cost $0.044, 1-month is aprox $32. You can see it clearly here https://instances.vantage.sh/aws/ec2/t3.medium?currency=USD&duration=monthly So it doesn't matter if the instance is receiving requests or not, as long as it is on, you are paying for it. Theen, you have all the other small charges, like data transfered from your instance to the outside, public IPs in use, etc, and some others not so small, like if you deployed a Load Balancer in front of your instance, that's hourly cost as well. You can ask Gemini, Copilot, ChatGPT, about the break down of costs of what you created, they can probably give you a good understanding about it. More on reddit.com

https://calculator.aws But you have to know which services you need to take into account. Best thing to do might be to reach out to AWS for the Migration Acceleration Program. They can connect you with a partner, and may be able to grant you credits, depending on the case and spend. More on reddit.com

If you have multiple instance types and don't want to add them one by one, you can try using AWS Calculator's bulk import feature. You can import the information via an Excel file. It's limited, but it might work for you. https://calculator.aws/#/bulk-import More on reddit.com

Check out this site as well for instance price comparison https://ec2instances.info/ More on reddit.com