Built a position size calculator that refuses to let you round up. Free, no signup
The single most expensive habit I had was sizing by feel and then rounding the share count up to something clean. 187 shares becomes 200 because 200 looks like a number. That rounding is a silent 7% increase in risk on every trade, and it compounds against you in exactly the periods you can least afford it.
So I built the calculator to be annoying about it. You give it account size, risk percent, entry and stop. It gives you the share count and it does not round. It also shows you the R value in dollars up front, because the point is to stop thinking in dollars and start thinking in R.
No signup, no email, nothing to buy. It's a static page, it runs in your browser, I don't see your numbers.
The unsexy conclusion after backtesting a bunch of my own setups: sizing discipline moved my expectancy more than any indicator I ever added.
Happy to explain the math in the comments if useful.
Free tools, three installable apps, and two SIGCSE 2026 papers. See the work or read the facts. Open to Summer 2027 software engineering, AI/ML, and quant internships.