How to Charge my clients for website designing?

hi folks,
i am working privately as a Web Developer. i also do freelance work. Recently i am having lots of freelance work to coupe up with. however till now i was giving my client as low as 20,000 Rs. (Pakistani Currency) charge. somehow i don’t feel that should be the prize. but i need solid ground to evaluate how to charge them so its ethical as well as good business. how do i calculate. what to charge.?

Have you seen the sticky at the top of this forum? There’s lots of great info there!

Also check the web design business kit