I don't recall the OP asking for your opinion on float. OP asked for a source on float and the core of your response was "Why?" which is a good question to ask you. Why do you reply with nothing of substance within the context of the question. P.S Float is VERY important in day trading (especially smaller cap stocks) and from your response alone I know you're a misinformed trader
They're usually close enough for what you're looking for. If you want to get it to the gnats ass, you'll have to look at the final S1-1A on a new issue, read the fine print with regards to the various lock-up stages, and break out a calculator. If it's an older stock, it's right there in quarterly report, any addendums subsequent to that will require them to file an 8K. At which point you break out the calculator again.