There are many ways to estimate your potential rewards.
The best calculator for calculating mining profits is
https://2cryptocalc.com/
You can also use other profit calculators.
https://whattomine.com/
However, there is another strategy. You can go to the "Mining Machine Online" page of the mining pool you have selected to find the computing power of mining machines similar to yours. Use his statistical data to understand how much ore you can mine in 1 hour/12 hours/1 day/1 week/1 month. If the mining machine you choose is on the line during the time period you are looking for, this method will be effective.