CPC & CPM Calculator
From ad spend, clicks and impressions, compute cost per click (CPC) and cost per mille (CPM, per 1,000 impressions).
輸入資料
計算結果
重點速覽：CPC = ad spend / clicks (cost per visit); CPM = ad spend / impressions x 1,000 (cost per 1,000 views). They map to the click and impression stages of the funnel. CPC suits performance ads; CPM suits awareness. WARNING: they are traffic prices, not returns — judge with CTR, conversion rate, CPA, ROAS. Education, not advice.
計算公式
CPC (每次點擊成本) = 廣告支出 ÷ 點擊數。
CPM (每千次曝光成本) = 廣告支出 ÷ 曝光數 × 1,000。
$$CPC = \dfrac{\text{Ad Spend}}{\text{Clicks}}$$$$CPM = \dfrac{\text{Ad Spend}}{\text{Impressions}} \times 1000$$使用說明
- Enter the campaign's total spend.
- Enter clicks and impressions.
- View CPC and CPM to assess traffic cost.
CPC 與 CPM 計算範例 (廣告支出 HK$50,000)
| 情境 | 點擊數 | 曝光數 | CPC | CPM |
|---|---|---|---|---|
| CTR 1.6% | 8,000 | 500,000 | HK$6.25 | HK$100.00 |
| CTR 1.0% | 5,000 | 500,000 | HK$10.00 | HK$100.00 |
CPM 相同 (曝光相同) 時，點擊數越多 (CTR 越高) CPC 越低 — CPC、CPM 與 CTR 三者透過 CPC = CPM ÷ (CTR × 10) 相連。
理財情境案例
案例一：同時計算 CPC 與 CPM
假設一波廣告支出 50,000 港元，帶來 500,000 次曝光與 8,000 次點擊。
CPC = 廣告支出 ÷ 點擊數 = 50,000 ÷ 8,000 = 6.25 港元 (每次點擊成本)。
CPM = 廣告支出 ÷ 曝光數 × 1,000 = 50,000 ÷ 500,000 × 1,000 = 100 港元 (每千次曝光成本)。此時點擊率 CTR = 8,000 ÷ 500,000 = 1.6%。CPC 衡量『把人帶進來』的成本，CPM 衡量『被看見』的成本，兩者一起看能診斷廣告是『曝光貴』還是『點擊差』。
案例二：CTR 下降如何推高 CPC
承上，若同樣支出 50,000、同樣 500,000 次曝光 (CPM 仍為 100)，但因素材吸引力不足，點擊數只有 5,000 (CTR 降到 1.0%)。
CPC = 50,000 ÷ 5,000 = 10 港元 — 比原本的 6.25 元高出 60%，即使 CPM 完全沒變。
這揭示三者的連動關係：CPC = CPM ÷ (CTR × 10)。當 CPM (買曝光的價格) 不變時，CPC 完全由 CTR 決定 — CTR 越高，同樣的曝光帶來越多點擊，攤薄後每次點擊越便宜。因此在 CPM 計價的廣告中，提升 CTR (優化素材、標題、受眾相關性) 是降低實際獲客流量成本的關鍵。
常見問題
Which should I use, CPC or CPM?
Depends on the goal. Performance ads (search, shopping) targeting clicks/conversions usually watch CPC; awareness/display ads targeting reach watch CPM. Practically view both with CTR to diagnose 'seen but not clicked' vs 'not enough reach'.
Is lower CPC/CPM always better?
Not necessarily — they only reflect the price of traffic, not return. Low CPC with non-converting traffic is wasted money; high CPC bringing high-value customers may be worth it. Judge with conversion rate, CPA and ROAS.
Why multiply CPM by 1,000?
Mille is Latin for a thousand — CPM is the cost per 1,000 impressions. Single-impression cost is tiny and awkward to compare, so the industry quotes per thousand, hence spend / impressions x 1,000.
Should I buy on CPC or CPM pricing?
CPM: you pay for impressions regardless of clicks — good for brand awareness and when you trust high CTR (fixed impression cost spread over many clicks lowers effective CPC). CPC: you pay only for clicks — good for performance goals and when creative performance is uncertain (risk shifts to the platform). Many platforms also offer CPA/oCPM smart bidding. Ultimately judge by CPA and ROAS.
Why multiply by 1,000 again?
CPM = Cost Per Mille, 'mille' = thousand in Latin, so it is literally 'cost per 1,000 impressions' — the x1,000 scales to that base unit for readability and industry convention. Single-impression cost (e.g. HK$0.10) is hard to read and compare; per-thousand lands in a sensible range (e.g. HK$100). To get single cost, divide CPM by 1,000; to estimate total cost, (target impressions / 1,000) x CPM. Always confirm whether 'impressions' means served or viewable.
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。