How to put a valuation on a website idea?

This is probably one of the hardest things to work out, before the dot bomb you could stick your finger in the air and come up with a figure. Now ofcourse it is very different.

Normally you would work out a cash flow forecast over three years giving worst, expected, best case turnover and come up with a figure from there. N x profit.

But if you have a social media site you would cost it on the value of your signups, 1 million signup worth x , 100 million signups worth y, see howmuch people have paid for u-tube etc to see the value.

Perhaps look at it a different way for the percentages, you have the idea so you want to retain control, so give yourself a figure that you are comfortable with say 70% then you have 30% to share out amongst the developers. Saying my company is going to worth millions based on an idea is wasting everyones time, just give a percentage and if they are happy then go for it.

Make sure you have everything in writing, work out what happens if at a later stage go for venture capital, write in that everyone takes and equal share drop.

Seek professional advice if you are serious, the above are just ideas.