Customer Acquisition Cost (CAC) Calculator
From total sales & marketing spend and new customers, compute the customer acquisition cost (CAC) and its ratio to revenue.
輸入資料
計算結果
重點速覽：CAC = total sales & marketing spend / new customers. With revenue per customer, CAC ratio = CAC / revenue per customer. Example: HK$100,000 spend, 500 customers → CAC HK$200; if revenue/customer HK$1,000, ratio 20%. Compared with LTV, LTV/CAC > 1 means acquisition pays back (3x+ commonly healthy); < 1 means losing money per customer. WARNING: Keep the spend window and customer count consistent (same period/channel); excluding a channel's fixed overhead understates CAC. Pair with LTV.
計算公式
總支出 = 行銷支出 + 銷售支出。
獲客成本 (CAC) = 總支出 ÷ 新增客戶數。
$$\text{CAC} = \dfrac{\text{Marketing} + \text{Sales}}{\text{New Customers}}$$使用說明
- Enter the sales & marketing spend for the period.
- Enter the new customers acquired in the same period.
- Optionally enter revenue per customer to see the CAC ratio.
以總獲客支出固定為 HK$120,000 (行銷 8 萬 + 銷售 4 萬) 為例，不同新增客戶數對應的獲客成本對照表
| 新增客戶數 | 總獲客支出 | 獲客成本 (CAC) | 說明 |
|---|---|---|---|
| 600 位 | HK$120,000 | HK$200 | 轉化效率高，CAC 低 |
| 400 位 | HK$120,000 | HK$300 | 表現良好 |
| 300 位 | HK$120,000 | HK$400 | 一般水平 |
| 200 位 | HK$120,000 | HK$600 | 成本偏高，須檢視 |
| 150 位 | HK$120,000 | HK$800 | 轉化偏弱，CAC 高 |
理財情境案例
CLTV∶CAC 比率:同樣 CAC $400，生意健康度天差地別
三間網店的 CAC 都是 HK$400，但每位客戶帶來的終身價值 (CLTV) 不同。
A 店 CLTV HK$1,600 → 比率 4∶1，遠高於健康門檻，可積極加大投放搶市佔;B 店 CLTV HK$1,200 → 比率 3∶1，剛好達標;C 店 CLTV HK$800 → 比率只有 2∶1，獲客投入回本慢，長遠恐難維持。
結論:CAC 本身不能判斷好壞，必須配合 CLTV 一起看。CLTV∶CAC ≥ 3∶1 通常視為健康;比率過低要設法提高留客與客單價，或壓低獲客成本。
提高轉化率如何直接壓低 CAC
某商戶每月固定花 HK$120,000 於行銷與銷售，原本每月吸到 200 位新客，CAC = HK$600。
團隊優化落地頁與廣告受眾後，轉化率提升，同樣的預算下每月新客增至 300 位，CAC 隨即降至 HK$400，單客成本減少三分之一。
若再把預算移向回報最高的渠道，新客升至 400 位，CAC 進一步降至 HK$300。
啟示:壓低 CAC 未必要減預算，提高轉化率、聚焦高效渠道，就能用同樣的錢吸到更多客。
常見問題
What does a healthy CAC look like?
It depends on your LTV (lifetime value). A common rule: LTV/CAC ≥ 3 means acquisition is efficient; between 1 and 3 is borderline; below 1 means you lose money on each customer and must fix the model or stop that channel. Also watch the payback period — how fast CAC is recovered from customer revenue.
How do I count the marketing spend correctly?
Include all acquisition costs in the period: ads, platform fees, agency, sales commissions, promotions, and a fair share of creative/tooling. Excluding parts understates CAC and flatters efficiency. Use the same window as the new-customer count.
How does CAC differ from CPA?
CAC is the cost to acquire a paying customer (revenue-generating). CPA (cost per acquisition) can mean any conversion — a sign-up, trial or lead — not necessarily a paying customer. CAC is stricter and ties to revenue; CPA can be broader. Be clear which you mean when comparing.
How do I lower CAC?
Raise conversion (landing page, funnel), improve targeting and creative, retain more (raises LTV, justifies higher CAC), focus high-ROI channels, and use referrals. But do not cut CAC so far that growth stalls — balance CAC against LTV and growth goals.
What is the CAC ratio and why use it?
CAC ratio = CAC / revenue per customer, showing acquisition cost as a share of customer value. Lower is better (cost recovered faster). It complements LTV/CAC and is handy when you only know per-customer revenue, not full lifetime value. Still, LTV is the fuller picture.
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貿易發展局（HKTDC）、工業貿易署中小企業支援與諮詢中心及投資者及理財教育委員會（IFEC）之相關指引，結果僅供參考，實際以相關機構公佈為準。