Share & ETF position sizer
Arithmetic, not advice. It sizes a position from numbers you type — it has no market data, no view on any instrument, and no idea whether your stop is sensible. Nothing you enter leaves your browser. A tight stop on an expensive share is the trap here: risking 1% can still ask for more capital than the account holds, and the position size looks reasonable right up until the margin call.
Risk and cost are different numbers
Shares come in whole units, so the size rounds down and your real risk lands slightly under the one you picked. That's the safe direction and needs no thought.
The trap is the other number. What a position risks and what it costs to open have nothing to do with each other. A tight stop on an expensive share means a large number of shares for a small risk — and the capital that requires can pass the whole account while the risk figure still reads 1%.
That's what share of account is for. Over 100% means the broker is lending you the difference, whatever the risk column says.