Average Fixed Cost (AFC) Calculator
Spread total fixed cost across output to get the average fixed cost per unit (AFC).
輸入資料
計算結果
重點速覽：AFC = total fixed cost / quantity. Fixed costs (rent, insurance, depreciation, fixed salaries) do not vary with output, so the more units produced, the lower the per-unit fixed cost — the source of economies of scale. AFC is only part of unit cost; add AVC for the full picture (ATC = AFC + AVC).
計算公式
平均固定成本 = 總固定成本 ÷ 產量。
$$AFC = \dfrac{\text{總固定成本 (TFC)}}{\text{產量 (Q)}}$$$$ATC = AFC + AVC \quad (\text{每單位總成本} = \text{平均固定成本} + \text{平均可變成本})$$使用說明
- Enter the total fixed cost (unchanged by output).
- Enter the output quantity.
- View the average fixed cost per unit.
總固定成本固定為 HK$500,000 時，不同產量對應的平均固定成本
| 產量 | 總固定成本 | 平均固定成本 (AFC) | 解讀 |
|---|---|---|---|
| 2,000 件 | HK$500,000 | HK$250.00 | 產量低，每件背負高 |
| 5,000 件 | HK$500,000 | HK$100.00 | 攤分改善 |
| 10,000 件 | HK$500,000 | HK$50.00 | 本工具預設值 |
| 20,000 件 | HK$500,000 | HK$25.00 | 產量倍增、AFC 減半 |
| 50,000 件 | HK$500,000 | HK$10.00 | 規模經濟顯著 |
理財情境案例
案例一：算出每件的平均固定成本
某工場每月固定成本 HK$500,000 (租金、牌照、保險、固定薪金與折舊)，月產 10,000 件。AFC = 500,000 ÷ 10,000 = HK$50 / 件。
這 HK$50 是每件產品要背負的固定成本;若當月產量下滑，這個數字會隨即上升，令成本結構承壓。
案例二：產量翻倍對成本的影響
同一工場若把月產量由 10,000 件提升到 20,000 件 (產能足夠、不需加租)，AFC 由 HK$50 降至 500,000 ÷ 20,000 = HK$25 / 件，每件省下 HK$25 固定成本。
但要注意：一旦產量超出現有產能、需加租多開一條線，固定成本會『跳升』到新水平，AFC 曲線會出現階梯式回升，並非無限下降。
常見問題
Why does higher output lower AFC?
Because the fixed-cost total stays the same but is spread over more units, so per-unit fixed cost keeps falling — economies of scale. At low output each unit bears a heavy fixed cost, stressing cost structure and pricing.
Is AFC the unit cost?
No. Unit total cost = AFC + AVC. This calculator covers fixed cost only; add per-unit variable cost (materials, packaging, piece wages) for the full unit cost before pricing and profit decisions.
What counts as fixed cost?
Costs paid no matter how much you sell — rent, licence fees, insurance, fixed salaries, equipment depreciation, loan interest. They stay constant within a capacity range; expanding capacity (e.g. renting another shop) steps fixed cost up to a new level.
How do AFC, AVC and ATC relate?
AFC is fixed cost per unit (falls with output); AVC is variable cost per unit (usually U-shaped); ATC = AFC + AVC is the full average unit cost. Because AFC keeps falling, ATC is pulled down at low output and pushed up by AVC at high output, so ATC is also U-shaped. Price off ATC plus target profit as the long-run floor, not AFC or AVC alone.
Why does the AFC curve never hit zero?
Mathematically AFC = fixed cost / quantity, so it approaches but never reaches zero (fixed cost stays positive). Also the decline is not perfectly smooth: fixed cost is constant only within a 'relevant range'; once output exceeds capacity and you expand (new premises, more managers), fixed cost steps up and AFC rebounds before falling again. So the real AFC curve is a series of downward steps, not one smooth line.
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。