You should start with a salary figure and then add time overhead, fixed expenses, hidden expenses, and the tax to come to the hourly rate that you should charge your clients.
Here is the detailed step by step of each expense to come to the final hourly rate for you.
Once you know your hourly rate, charge for a WordPress website based on the time you need to deliver.
However, one should note that many developers are charging $10 per hour, and my charges are $50+ per hour. It doesn’t mean I develop five times faster than the person working at $10 per hour. It means that when my code is executed in a very high traffic environment, it doesn’t break that easily.
Let me share an example. A client wanted a JSON output of some data, and there was an address in the data, so it needed Google latitude and longitude for the address.
I asked a developer to provide me a quote, and he said he could get it done in a couple of hours using a third-party tool. My question was, why not Google itself. His answer was it is too complicated for an API.
So I did the code using Google API, and it took me more than a couple of hours.
However, it meant my code is much more stable. Furthermore, I am not fetching information and caching a faster JSON response until the address doesn’t change.
Clients may not have the ability to judge why even a $50 per hour person is quoting it for 5 hours when a $10 per hour person is quoting it to be a couple of hours work. So you have to let the client know why you are charging more per hour and will need more hours to get the task done.