Generally, as you're using Railway through the month, your total application resource usage will be counted and you will be charged for that usage at the end of the billing cycle (which lasts a month).

- On hobby plan, the plan itself costs 5 dollars, but it comes with 5 dollars of usage. Meaning you subtract 5 dollars of usage for the included usage from the total cost, but then add 5 dollars for the plan's base cost. This cancels each other out though so the simpler way to think about it is that on the hobby plan you pay for the resources you use at a minimum of 5 dollars.
- On pro plan, you pay 20 dollars for every person on the plan, then you also pay for usage.

There is no approximate cost because it is completely dependent on what you host and the resources that application uses.

Read more:
- https://railway.app/pricing
- https://docs.railway.com/reference/pricing/plans

Thank you