Closed-trade gain, cost basis with commission, and ROI — before tax.
Cost is shares × buy price, plus any commission you enter. Proceeds are shares × sell price. Profit is proceeds − cost. ROI is profit ÷ cost × 100. A $50 buy to a $55 sell on 100 shares with $0 fees is $500 profit and 10% ROI; the same trade with $25 round-trip fees is $475 profit and a slightly lower ROI because cost rose.
That is why fee fields matter on small accounts. A $7 commission on a $400 position is material; on a $40,000 position it barely moves ROI. Enter the real fee your broker charged (or still charges for special orders, OTC, or international routes) so the percentage matches your blotter — not a fantasy fill.
To break even after a fixed commission C on S shares bought at B, you need roughly sell ≥ B + C/S when the fee sits on the buy side (ignoring sell-side fees split). If fees hit both legs, add both into the commission field as a total dollar drag. This page shows profit at the sell price you type; nudge sell until profit hits zero if you want the break-even printout by hand.
The model assumes you bought first and sold later (a long). Shorts reverse the cash flow timing and may include borrow fees — not modeled. Partial exits need multiple runs (one per lot) or a weighted average buy. Dividend adjustments, corporate actions, and FX conversion sit outside this tool.
No tax lot matching, no wash-sale tracking, no options Greeks, no crypto funding rates. Short-term vs long-term capital gains rates are off-page — talk to a tax pro for realized gains reporting. For position sizing before you enter, use Position Size; for R-multiples, use Risk/Reward; for percent-only math, use Percentage; for portfolio-style return labels, use ROI.
Paper-trading tip: run the same shares and prices once with $0 commission and once with your real fee so you feel how much edge fees consume. If ROI only looks good with zero fees, the idea is not ready for a live ticket.
Educational estimate only. Not investment advice. Charts: TradingView partner link above. As an Amazon Associate, DynDisc earns from qualifying purchases on Picks.