Cost of Doing Business Calculator
From fixed cost, variable cost and units produced, compute the total cost and the cost per unit.
輸入資料
計算結果
重點速覽：Total cost = fixed cost + variable cost; cost per unit = total cost / units. It decomposes operating cost into volume-independent (rent, payroll) and volume-dependent (materials, commission) parts. In Hong Kong, high fixed costs (rent, wages) mean volume is key to lowering unit cost — the more units, the more fixed cost is spread. Core of unit economics and break-even. WARNING: variable cost is total, not per unit; match period/capacity and classify costs correctly. Education, not advice.
計算公式
總營運成本 = 固定成本 + 變動成本。
每單位成本 = 總營運成本 ÷ 單位數。
$$\text{Total Cost} = \text{Fixed Cost} + \text{Variable Cost}$$$$\text{Cost Per Unit} = \dfrac{\text{Total Cost}}{\text{Units}}$$使用說明
- Enter the fixed cost for the period.
- Enter the total variable cost.
- Enter the number of units to see total cost and unit cost.
以固定成本 HK$500,000、每單位變動成本 HK$30 為例，產量由 5,000 件增至 40,000 件時的總成本與每單位成本變化，展示規模經濟如何攤薄固定成本。
| 產量 (件) | 固定成本 (HK$) | 變動成本 (HK$) | 總成本 (HK$) | 每單位成本 (HK$) |
|---|---|---|---|---|
| 5,000 | 500,000 | 150,000 | 650,000 | 130.0 |
| 10,000 | 500,000 | 300,000 | 800,000 | 80.0 |
| 20,000 | 500,000 | 600,000 | 1,100,000 | 55.0 |
| 40,000 | 500,000 | 1,200,000 | 1,700,000 | 42.5 |
理財情境案例
個案一：規模經濟壓低單位成本
一間香港小型製造商固定成本 (廠房租金、設備、管理層月薪) HK$500,000，每件產品的變動成本 (原料加計件工資) 為 HK$30。
產量 5,000 件時，每件要分攤 HK$100 的固定成本 (500,000 ÷ 5,000)，加上 HK$30 變動成本，每單位成本高達 HK$130;但當訂單增至 40,000 件，每件只需分攤 HK$12.5 固定成本，每單位成本降到 HK$42.5。同樣的產品，產量放大令單位成本大降近七成，這就是規模經濟的威力 — 也解釋了為何爭取大訂單、提高產能利用率，對製造業的成本競爭力如此關鍵。
個案二：每單位成本是定價的底線
承上例，該製造商在產量 10,000 件時，每單位成本為 HK$80。一個客戶出價每件 HK$75 想大量採購。
由於 HK$75 低於每單位成本 HK$80，若照單全收，每賣一件反而虧 HK$5，這種訂單原則上不划算。但要注意：若這是『額外增量訂單』且產能有餘，決策應改看『變動成本 HK$30』— 只要售價高於變動成本，這張額外訂單仍能貢獻覆蓋部分固定成本 (參見邊際貢獻概念)。這說明每單位成本 (含固定成本分攤) 是『正常定價』的底線，但在產能有餘的增量決策中，變動成本才是真正的底線，兩者要分清場景運用。
常見問題
What is the difference between fixed and variable cost?
Fixed costs stay roughly constant in the period (rent, salaried payroll, insurance, depreciation); variable costs move with volume (materials, piece wages, commissions, usage-based utilities). Mixed costs must be split. Classification is relative to the period and capacity range.
How does this relate to unit economics and break-even?
Unit cost = total cost / units; compare with selling price for gross margin. Break-even units = fixed cost / (price - unit variable cost) — once exceeded, each unit contributes profit. Lower unit cost (via higher volume) widens the margin.
Why is unit cost lower at higher volume?
Because fixed cost is spread over more units — fixed cost per unit falls as volume rises, a scale effect (economies of scale). At very high volume, fixed cost per unit approaches zero but variable cost per unit stays, so unit cost converges to variable cost per unit.
What is the Hong Kong context for cost of doing business?
Hong Kong's high commercial rent and wages make fixed costs a heavy burden for SMEs (shops, F&B, studios) — so volume and pricing discipline are critical; low sales can't cover fixed costs and quickly turn losses. The HKTDC and HKPC offer SME support and benchmarks; pair with the break-even and contribution-margin calculators. Education, not advice.
What does 'units' mean, and is higher volume always better?
'Units' is the quantity produced/sold in the period, in any unit (pieces, orders, service hours). Higher volume lowers unit cost via spreading fixed cost, but only if sold at a profit — if the selling price is below total unit cost, more volume means more loss. Also watch capacity: beyond capacity, fixed cost jumps (new shop, more staff) and unit cost rises again. So 'higher volume lowers unit cost' holds within a capacity range; the goal is the profitable volume that clears break-even, not volume at any cost.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。