How to calculate PPC for a keyword?

[stcole]

How can I determine the PPC rate which I should pay for each click on my keyword? I am starting a new site. And I am thinking about starting a Google Adword campaign to promote it.

[frank]

Well the amount of money which you will have to pay per click for your keyword will be shown in Google Adwords. Expect that you will have to pay 20-25% extra to the suggested bid.
You can't assume a certain figure unless you start a campaign. Test it and see how much is your click through rate. A click through rate of about 6-10% is always good. You will have to pay less (lower bids) if your CTR is good and if its not then you may have to overpay. So, make your ad as much as attractive to get the maximum attention of the users that the ads will be shown to.

[Paul]

You will also have to keep in mind the project you are handling. The project type matters too. Are you using the ad campaign to get sales or just its for exposure. If you are doing it for sales then it changes the metrics.
Suppose you are getting a 8% CTR and none of them are buying your products then its a total waste of money. And if you are getting a CTR of about 4% but most of them are buying it then its good.
Consider all the elements from top to bottom and test that in your ad campaign. You can't just assume while just seeing the bids in Google keyword planner.