CPM (Cost Per Mille) Calculator
From ad cost and impressions, compute the cost per 1,000 impressions (CPM).
輸入資料
計算結果
重點速覽：CPM = ad cost / impressions x 1,000 — the cost to show the ad 1,000 times. It benchmarks reach campaigns (display, video, OOH). Lower CPM = cheaper reach, but it only measures reach cost, not clicks or conversions. Pair with CPC/CTR/CPA. WARNING: low CPM with imprecise/bot traffic is wasted; compare on viewability and conversion, not just price. Education, not advice.
計算公式
CPM = 廣告成本 ÷ 曝光次數 × 1,000。
$$CPM = \dfrac{\text{Cost}}{\text{Impressions}} \times 1000$$使用說明
- Enter the total ad spend.
- Enter total impressions.
- View the cost per 1,000 impressions (CPM).
CPM (每千次曝光成本) 計算範例
| 情境 | 廣告成本 | 曝光次數 | CPM |
|---|---|---|---|
| 基準 | HK$5,000 | 800,000 次 | HK$6.25 |
| 曝光減少 | HK$5,000 | 500,000 次 | HK$10.00 |
| 成本增加 | HK$8,000 | 800,000 次 | HK$10.00 |
CPM = 廣告成本 ÷ 曝光次數 × 1,000。在成本固定下，曝光越多 CPM 越低；CPM 是比較不同渠道『買曝光』價格的通用標尺。
理財情境案例
案例一：計算 CPM
假設一波品牌廣告花費 5,000 港元，共獲得 800,000 次曝光 (廣告被展示的總次數)。
套用公式：CPM = 廣告成本 ÷ 曝光次數 × 1,000 = 5,000 ÷ 800,000 × 1,000 = 6.25 港元。
這代表：每讓廣告被展示 1,000 次，成本為 6.25 港元。CPM 是品牌曝光型廣告最核心的採購指標 — 當目標是『讓最多人看見』而非立即點擊時，CPM 越低代表觸及成本效益越高。
案例二：用 CPM 比較不同渠道
假設渠道 A：花 5,000 換 500,000 次曝光 → CPM = 5,000 ÷ 500,000 × 1,000 = 10 港元;渠道 B：花 8,000 換 800,000 次曝光 → CPM = 8,000 ÷ 800,000 × 1,000 = 10 港元;渠道 C (案例一)：花 5,000 換 800,000 次曝光 → CPM = 6.25 港元。
三個渠道花費與曝光量各不相同，直接比『總花費』或『總曝光』都無法判斷誰划算，但換算成 CPM 後一目了然：渠道 C 的 CPM 最低 (6.25)，買曝光最便宜。
這正是 CPM 的價值 — 它把不同規模的廣告投放，統一到『每千次曝光要花多少錢』的共同基準上，讓跨渠道、跨活動的曝光成本可以對等比較。但要提醒：CPM 只衡量『曝光成本』,不代表成效;低 CPM 若伴隨低 CTR 與低轉化，實際的 CPC 與 CPA 未必划算，仍須綜合看整條漏斗。
常見問題
What is the difference between CPM and CPC?
CPM prices per 1,000 impressions (reach/awareness); CPC prices per click (traffic/conversion). One campaign can show both: CPM for reach cost, CPC for traffic efficiency.
Is lower CPM always better?
Not necessarily. Low CPM means cheap reach, but if the audience is imprecise, impressions are invalid/bot, or the ad is not viewable, it is wasted. Judge with viewability, audience fit and final click/conversion.
How do I compare media using CPM?
Plug each channel's spend and impressions into the formula to get its CPM, then compare on the uniform 'per thousand impressions' basis. Ensure impressions are defined consistently (e.g. viewable) and weigh audience fit and conversion too.
What is an impression / viewable impression?
An impression is one ad load/serve — counted even if the user never scrolled to see it. Viewable impressions (per IAB/MRC) require ≥50% of the ad visible for ≥1 second (video often ≥2s), filtering 'seen' from 'served'. vCPM prices on viewable impressions. The impressions you enter should state which definition is used.
Does low CPM mean the ad is worthwhile?
No — low CPM only means cheap reach, not effectiveness or profit. Down the funnel, low CPM with terrible CTR yields high effective CPC; low conversion yields high CPA. Real goal is acceptable CPA/ROAS, not the lowest CPM. Sometimes paying higher CPM for precise, quality reach is cheaper overall. Use CTR and CPA calculators to diagnose the whole funnel.
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。