以下详细说明暂以英文提供。
What counts as profit
Trade profit is simple at heart: what you sold for, minus what you paid, minus the costs of getting in and out. Commissions and fees nibble at the edges, and dividends can quietly become a large share of total return over years of holding. This calculator keeps all three visible so a trade that “made money” does not hide a fee drag, and a flat trade does not hide income the dividends delivered.
Reading ROI on the position
ROI here divides net profit by your cost basis, the money tied up in the position. A $2,000 profit sounds nice, but 40% on a $5,000 position in six months is very different from 40% over ten years — pair this result with the CAGR calculator when you want returns per year. Taxes come off the top too, and short-term gains usually take the bigger bite.
中国本地参考
在中国大陆做财务换算时，以下框架值与美国默认值差异很大：
- 个人所得税: 工资薪金基本减除费用为 5,000 元/月（60,000 元/年），综合所得适用 3%–45% 七级超额累进税率（自 2019 年起施行）。
- 社保与公积金: 养老保险单位缴费 16%、个人 8%；住房公积金常见缴存比例为 5%–12%，由各城市确定上下限。
- 价签与增值税: 标价为含税价（一般纳税人增值税率 13%/9%/6%），结账时不额外加税，与美国小票加税习惯不同。
- 数字与单位: 使用公制单位（厘米、米、千克、升），温度为摄氏度；人民币符号 ¥，千分位用逗号、小数用点：12,345.67 元。
- 小费文化: 餐厅不付小费，部分场所收取服务费并已在账单中标明；无需按美式 15%–20% 计算。
数据核对：2026 年 10 月
常见问题
Do I need to enter commissions?
No — many brokers trade commission-free, so the defaults are zero. If you pay a flat fee per trade or per share, enter the dollar amount for each side and it comes straight off profit.
How do dividends fit in?
Enter the total dividends paid per share while you held the stock. They are added on top of trading profit to show total return, which is how long-term investors often earn most of their money.
What if I only sold part of my position?
Enter the shares you actually sold and the prices for that lot. The remaining shares are an open position with no realized profit until you sell them.