Customer Churn Rate Calculator
From starting customers and customers lost in a period, compute the churn rate and the retention rate.
輸入資料
計算結果
重點速覽：Churn rate = customers lost / starting customers x 100%; retention = 100% - churn. Example: 1,000 start, 120 lost → 12% churn, 88% retention. Lower churn is better. WARNING: State the period (month/quarter/year) — a 2% monthly churn ≈ 21.5% annualised; distinguish customer churn from revenue churn (losing low-value customers may barely affect revenue). Reducing churn is usually cheaper than acquiring. Education, not advice.
計算公式
客戶流失率 = 期間流失客戶 ÷ 期初客戶 × 100%。
留存率 = 100% − 流失率。
$$客戶流失率：$Churn=\dfrac{Lost}{Start}\times100\%$$$$$留存率：$Retention = 100\% - Churn$$$$$月流失年化：$1-(1-churn_{月})^{12}$$$使用說明
- Enter the starting customer count.
- Enter the customers lost in the period.
- View the churn and retention rates.
不同期初與流失客戶數下的流失率與留存率
| 期初客戶 | 期間流失 | 流失率 | 留存率 |
|---|---|---|---|
| 1,000 | 20 | 2% | 98% |
| 1,000 | 50 | 5% | 95% |
| 1,000 | 120 | 12% | 88% |
| 500 | 75 | 15% | 85% |
理財情境案例
案例一：計算月度客戶流失率與留存率
某訂閱制服務月初有 1,000 位客戶，該月內有 120 位取消或停用。
流失率 = 120 ÷ 1,000 × 100% = 12%；留存率 = 100% − 12% = 88%。
解讀：這個月流失了 12% 的客戶，只留住了 88%。12% 的月流失對訂閱生意來說相當高——意味著每個月都要拉到至少同等數量的新客才能維持規模，獲客成本 (CAC) 會不斷攤薄回報。應盡快拆解流失原因、針對高風險客群挽留。
案例二：別被『低月流失率』騙了——年化的威力
A 公司月流失率 2%，B 公司月流失率 5%，單看數字都不算高。但把它們年化 (假設每月流失率穩定),差距就非常驚人。
A：年化流失 = 1 −(1 − 0.02)^12 ≈ 21.53%。B：年化流失 = 1 −(1 − 0.05)^12 ≈ 45.96%。
解讀：月流失 2% 的 A 公司，一年會流失約兩成客戶；月流失 5% 的 B 公司，一年竟流失近一半客戶。這說明看流失率絕不能只看單月的表面數字——月度的小差異，經過一年的複利式累積會被放大成巨大鴻溝。設定目標與比較時，務必統一週期並理解年化後的真實衝擊。
常見問題
What period should I use for churn?
State it explicitly (month, quarter or year) and keep it consistent. A 2% monthly churn looks tiny but annualises to over 20% (1 - 0.98^12 ≈ 21.5%). Always compare or set targets on the same period — never mix monthly and annual churn.
Is customer churn the same as revenue churn?
No. Customer churn counts how many customers left; revenue churn counts how much revenue left. If the lost customers are low-spend, revenue impact may be small; if you lose a few big accounts, revenue churn can be huge despite a low customer count. Subscription businesses should track both.
How do I reduce churn?
Find the causes and high-risk segments (inactive, complained, near renewal), then target retention: improve product experience, proactive outreach, renewal offers or loyalty rewards. Since keeping a customer usually costs far less than acquiring one, investing in retention often pays more.
Why is reducing churn usually cheaper than acquiring?
In most industries, retaining an existing customer costs far less than acquiring a new one (which needs ads, sales, discounts). And existing customers are likelier to upgrade and refer. High churn is a 'leaky bucket' — you spend dear money on acquisition just to refill losses. Fix the leak (lower churn) first; healthy growth combines low churn with steady acquisition.
What is net revenue churn?
Net revenue churn nets expansion (upgrades, cross-sell) from losses. If existing customers' growth offsets churn, net revenue churn can even be negative (revenue grows despite churn). So customer churn alone can under- or over-state the financial impact; analyse it alongside revenue dimensions.
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。