When the form is asking you this, it is asking you to think about how much much total revenue (money) you will receive and compare that to how much money you receive for just that specific product. Remember that revenue is not profit - it is just how much money you receive in sales.

For example, if I expect my blacksmith shop to bring in about $5000 a month in sales, and that includes my estimate of $800 in axes, then I need to know what percentage is $800 of $5000.

To calculate this kind of percentage, you just multiply the smaller number by 100 and then divide by the larger number. So for my example, 800 X 100 / 5000. That's 16%.

Hope this helps,
Stephen La Rocque.