以下详细说明暂以英文提供。
The break-even math
Every sale first pays for the cost of making that one item; whatever remains is the contribution margin that chips away at fixed costs. Break-even happens when enough margins have accumulated to cover the fixed block: fixed costs ÷ contribution margin per unit. A $20 margin against $10,000 of fixed costs needs exactly 500 sales — each sale after that drops the full $20 to the bottom line.
Using break-even to make decisions
Break-even is a lever you can pull from either side. Raising price widens the margin and lowers the units needed, but usually costs some volume; trimming the variable cost (a cheaper supplier, less waste) does the same without touching the shelf price. Cutting fixed costs lowers the bar outright. Compare the units required against realistic demand — a break-even point the market cannot support is a signal to redesign the plan, not to try harder.
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
What counts as a fixed cost?
Costs that do not move with each sale over the period: rent, salaries, insurance, software subscriptions, loan payments. A cost that only appears when you produce a unit belongs in the variable column.
Why round the break-even units up?
A fraction of a sale cannot cover its share of fixed costs, so 500.2 units still means 501 sales in practice. The exact figure is shown too, since it is the one to use for revenue math.
Can I use this for a service business?
Yes — treat each engagement or client hour as a “unit.” Fixed costs are your monthly overhead, price is the fee, and variable costs are whatever delivering that unit costs you.