Free Trader Calculators
Three calculators that handle the math you'd otherwise do in a notebook before every trade. No signup, no popups, runs entirely in your browser.
Position Size Calculator →
How many shares to buy given your account size, risk per trade, entry, and stop.
Average Down Calculator →
Blended cost basis across multiple buys, with unrealized P&L and break-even %.
Trailing Stop Calculator →
Where your trailing stop sits given peak price and trail %, plus locked-in profit.
Why we built these
We build Fuselit, an automated trading layer on top of Alpaca that handles position sizing, trailing stops, and rebuys without spreadsheets. These calculators do one thing each, for free, for anyone — even if you never sign up.