on design jobs that I do, I use a similar formula as above however slightly modified.
First step is to sit down with the client and decide exactly what they want. Make a structured list from these things. Then tell them you will get back with them soon with a quote. Now take this list, beside each item write how many hours you expect each one to take. Next, total your hour up, then multiply by your hourly wage.
Finally, I use something I call a project price. After I get the hours expected and multiply that by the hourly wage. I then deduct say 15% from that number and come up with a project price. I do this because the person is buying my services in bulk and I am able to work faster than having to start and stop with small projects.
These are some links to get your started, but I recommend you do some more thorough research. Charging $20 doesn't cut it, and helps to saturate the web design market even more.
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