Some people asked about my Position Size spreadsheet. I like it because it's simple and quick to reference. I made a print and taped it to my monitor. The concept is, decide how much you are willing to lose on any given trade. For me, it's 1% of my $30k account = $300. Determine what your stop loss is (ie, the difference between your entry and your stop). Say it's 50 cents per share (0.50 $/sh). The number of shares to trade is $300 / 0.50 $/sh = 600 shares. For you mathematicians, you see the units check out: ($) / ($/share) = shares.