The formula for Clickbank fees is as follows:
Product Price - 7.5% - $1 = Net * commission rate.
So say if the product is $37..
$37 - 7.5% - $1 = $33.225
So say if the vendor sets commission rate at 75%... you will get: $33.225 * 75% = 24.92 (rounded off).
Yes, all Clickbank fees calculator are correct. But here's the problem: most vendors have set 'exit price discounts'. So say if a lead tries to leave the page they will get that cheesy "Hold On! Get your special discount now! Get xxx for just $27!"
So now your commission will become : $27 - 7.5% - $1 = 23.975 * 75% (commission rate) = $17.98
Then there are upsells too. You never know if a customer buys any upsell products. And these upsell products may have discount pages too.In case if anyone is wondering they are called "Upsell Flows"...
Like after purchase of the initial product, the customer is taken to the first upsell product salespage. If the customer buys it, he/she will be brought to the second upsell product page; however, if say he/she declines the first upsell product page, he/she will be redirected to another page that shows a discounted price for the first upsell product page. If the customer accepts and buys it, he/she will be brought to the second upsell salespage. And so on. Usually, there are up to 3 upsell product pages for most vendors, though it really varies and most new vendors usually fail to utilise this opportunity or fail to make a discounted upsell page when the customer rejects the initial offer.
Anyway, the Clickbank fee calculator is useful if you want to know the exact profit you'll get from a sale. But it isn't definite as you never know if there are 'exit discount' pages and the customer buys it from there or if the customer purchases any upsell products. So it would be inaccurate when you're going to use it for analyzing your PPC campaigns and what not.
Hope that helps!