CPM Calculator — Cost per Mille, CPC, CPA & CTR
Work out CPM, ad spend or impressions from the other two, plus CPC, CPA, CTR and conversion rate on one page.
CPM (cost per 1,000 impressions)
CPM = ad spend ÷ impressions × 1,000 · Spend = CPM × impressions ÷ 1,000 · Impressions = spend ÷ CPM × 1,000
CPC (cost per click)
CPC = ad spend ÷ clicks · Clicks = spend ÷ CPC
CPA (cost per acquisition / conversion)
CPA = ad spend ÷ conversions · Conversions = spend ÷ CPA
CTR and conversion rate
Clicks more than impressions, or conversions more than clicks, usually means the numbers come from different date ranges or attribution windows.
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This CPM calculator works out cost per thousand impressions from your ad spend and impressions, or solves the other way round: how much a given number of impressions will cost at a quoted CPM, or how many impressions a budget buys. The same page has calculators for CPC (cost per click), CPA (cost per acquisition), click-through rate and conversion rate, so you can check a whole campaign’s funnel in one place.
The formulas are simple, but they are easy to get wrong under deadline: CPM multiplies by 1,000, CTR divides clicks by impressions, and conversion rate divides by clicks, not by impressions. Each card shows the formula it used. The benchmark figures on this page are rough averages from public studies; your own historical numbers are always the better comparison.
How to use
- Choose your currency.
- In the CPM card, choose what to solve for (CPM, ad spend or impressions) and enter the other two values.
- Use the CPC and CPA cards the same way with clicks and conversions.
- Enter impressions, clicks and conversions in the last card to get CTR and conversion rate.
- Copy the results to paste into a report or media plan.
Frequently asked questions
How do you calculate CPM?
CPM = total ad spend ÷ impressions × 1,000. For example, $2,500 spent for 400,000 impressions is 2,500 ÷ 400,000 × 1,000 = $6.25 CPM. To find the cost of a campaign from a CPM rate, multiply the CPM by impressions and divide by 1,000; to find impressions from a budget, divide the budget by the CPM and multiply by 1,000.
What does CPM stand for?
Cost per mille, from the Latin for thousand. It is the price of 1,000 ad impressions. Publishers use the same maths for RPM (revenue per mille) and eCPM (effective CPM), which express earnings or the cost of non-CPM buys, such as CPC campaigns, per 1,000 impressions so they can be compared.
What is a good CPM?
It depends heavily on platform, country, audience and season. As a rough guide for US audiences, Meta (Facebook and Instagram) CPMs often fall somewhere around $5–15, display networks can be a few dollars, and LinkedIn is typically much higher, frequently $30 or more. CPMs rise sharply in Q4 as retailers compete. A low CPM is only good if the impressions reach people who click and buy, so judge it alongside CPA.
What is the difference between CPM, CPC and CPA?
They price different steps of the funnel. CPM is the cost of 1,000 impressions, CPC the cost of one click, and CPA the cost of one conversion (a sale, lead or sign-up). They are linked: CPC = CPM ÷ (CTR × 1,000), and CPA = CPC ÷ conversion rate. If your CPA is too high, these relationships tell you whether the problem is expensive reach, a weak ad (low CTR) or a weak landing page (low conversion rate).
How do you calculate CTR and conversion rate?
CTR = clicks ÷ impressions × 100. Conversion rate = conversions ÷ clicks × 100. For 3,200 clicks from 400,000 impressions and 96 conversions, CTR is 0.8% and conversion rate is 3%. Some platforms define conversion rate per session or per visitor instead of per click, so check which one your report uses before comparing.
Formula reference
• CPM = spend ÷ impressions × 1,000
• CPC = spend ÷ clicks
• CPA (or CPL for leads) = spend ÷ conversions
• CTR = clicks ÷ impressions
• Conversion rate = conversions ÷ clicks
• eCPM from CPC = CPC × CTR × 1,000
• CPA from CPM = CPM ÷ (1,000 × CTR × conversion rate)
The last line is the useful one in planning: a $10 CPM with a 1% CTR and a 2% conversion rate gives a CPA of 10 ÷ (1,000 × 0.01 × 0.02) = $50. Halving CPM or doubling either rate each halves the CPA.
Rough benchmarks, and how to use them
WordStream’s 2024 Google Ads benchmark study reported an all-industry average search CTR of about 6.4%, average CPC of about $4.66 and average conversion rate of about 7%. Display and social CTRs are far lower, commonly under 1%. These are rough averages across very different industries; legal and finance keywords can cost ten times what retail keywords do.
Use benchmarks to spot something badly off, such as a search CTR under 1%, which usually means poor keyword match or ad copy. Use your own past campaigns to set targets. And make sure every campaign link is tagged with UTM parameters, or your analytics cannot tie conversions back to the spend you are dividing by.
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