CPM Calculator

Background.

CPM — cost per mille, from the Latin for thousand — is the price of buying one thousand ad impressions, and it is the oldest and most universal number in media buying. This calculator solves the CPM identity in whichever direction you need it. Measuring a campaign that already ran? Enter what you spent and how many impressions were delivered, and it returns the CPM. Planning one against a publisher's quoted rate? Switch the dropdown and it returns either the cost of a target impression volume or the impression volume a fixed budget will buy. The three modes are the same equation rearranged, and they round-trip exactly.

Read the headline number for what it is. CPM tells you what impressions cost. It says nothing whatsoever about whether those impressions were worth buying. A $2 CPM against an audience that will never buy your product is a worse outcome than a $20 CPM against an audience that will, and no amount of CPM optimisation fixes a bad audience. CPM is a denominator you divide performance by — not a performance metric in its own right. Media buyers who chase the lowest CPM in a programmatic auction reliably end up with the cheapest inventory for exactly the reason it was cheap.

That is why this page also computes viewable CPM. A served impression is an ad delivery: the ad server responded to a request and the creative was sent. Whether any human had an opportunity to see it is a separate question, and the industry has a formal answer to it. The Media Rating Council's Viewable Ad Impression Measurement Guidelines, version 2.0 of 18 August 2015, count a display impression as viewable only when at least 50% of the advertisement's pixels are on an in-focus browser tab in the viewable browser space, and the pixel requirement is met for at least one continuous second after render. Larger formats — 242,500 pixels or more, the size of a 970×250 billboard — clear at 30% of pixels for the same one second. Video needs 50% of pixels for two continuous seconds of play. Enter the viewability rate your ad server actually reports and the calculator restates your buy as a cost per thousand impressions that met that bar.

The viewability field defaults to 100%, and that default is deliberate. It means "unmeasured", and it makes viewable CPM equal CPM, which is the honest answer when you have no measurement. This page does not assume an industry-average viewability rate on your behalf, because no such average is stable across formats, placements, geographies or years, and inventing one would quietly corrupt every number underneath it. Read the figure off your Active View column or your MRC-accredited vendor's report, or leave the field alone.

One more limit worth internalising before you trust the output: impressions are not people. An impression counts a delivery, so one person who sees your ad six times generates six impressions. The number of distinct humans reached, and how often each of them saw the ad, are reach and frequency — separate quantities that this calculator does not compute and that no CPM figure contains. A campaign with 750,000 impressions might have reached 500,000 people twice or 50,000 people fifteen times, and those are wildly different campaigns at an identical CPM.

A worked example, computed by the same code that runs the widget: a $4,500 buy that delivered 750,000 impressions has a CPM of exactly $6.00. If your ad server reports that 62% of those impressions were viewable, 465,000 impressions cleared the MRC bar and your viewable CPM is $9.68 — you paid $6.00 for a thousand deliveries and $9.68 for a thousand genuine opportunities to see. Flip the dropdown to cost and a $6.00 rate over 750,000 impressions gives back $4,500. Flip it to impressions and a $4,500 budget at $6.00 buys back 750,000. Every arithmetic step runs at arbitrary decimal precision and rounds only once, at the moment of display, so the viewable figure is derived from the true CPM rather than from the two-decimal number on your screen.

CPM is one of three canonical media pricing models, and the IAB's own glossary treats them as a family: the x in "CPx" is replaced by M for thousand impressions, C for click, or A for action. You buy on CPM when the objective is exposure, on CPC when you are paying for traffic, and on CPA when you are paying for outcomes. Quanta publishes a separate calculator for each, plus a ROAS calculator for the revenue side of the ledger, because they answer genuinely different questions rather than restating one another.

What is cpm calculator?

CPM stands for cost per mille — cost per thousand — and is the amount an advertiser pays for one thousand ad impressions. The IAB's Glossary of Interactive Advertising Terms defines it as "cost per thousand ad impressions, an industry standard measure for selling ads on websites," noting that the measure is inherited from print advertising and that the M is the Roman numeral for a thousand. The arithmetic is agreed across every authority that publishes a formula: the AMA Dictionary entry carried by the MASB Universal Marketing Dictionary gives CPM = advertising cost ÷ impressions generated in thousands, and Farris, Bendle, Pfeifer and Reibstein set out the same identity in Marketing Metrics chapter 9, section 9.2. An impression, per the IAB, is a response from a web server to a page request, filtered for robotic activity and error codes and recorded as close as possible to the user's opportunity to see the page — so it counts an ad delivery, not a person and not a view. Viewable CPM, or vCPM, prices the same buy against the subset of impressions that met the Media Rating Council's viewable-impression standard: at least 50% of the ad's pixels in the viewable browser space for at least one continuous second for display, 30% for large formats of 242,500 pixels or more, and 50% of pixels for two continuous seconds of playback for video. Because viewable impressions are always a subset of served impressions, vCPM is always greater than or equal to CPM, and the gap between them is a direct measure of how much of your media budget bought inventory nobody had a chance to see.

How to use this calculator.

1. 01Choose what to solve for. Leave it on CPM to measure a buy that already ran. Switch to Campaign cost when a publisher has quoted you a rate and you know the impression volume you want. Switch to Impressions when you have a fixed budget and want to know what it buys.
2. 02Enter the ad spend — the total media cost for this line item. Use net cost if your CPM is quoted net of agency commission, gross if it is quoted gross; mixing the two is the most common way a media plan drifts. Leave this field alone if you selected Campaign cost.
3. 03Enter the impressions — ad deliveries, taken from your ad server or the publisher's delivery report. Leave this field alone if you selected Impressions.
4. 04Enter the CPM rate if you are planning rather than measuring. This is the price for one thousand impressions from the rate card or insertion order. Leave it alone if you selected CPM.
5. 05Enter your viewability rate only if you actually measure it. Copy the percentage from your Active View column or your MRC-accredited verification vendor. If you do not measure viewability, leave the field at 100% — viewable CPM will then equal CPM, which is the correct answer when the data does not exist.
6. 06Read the outputs together. CPM is what a thousand deliveries cost. Viewable CPM is what a thousand genuine opportunities to see cost. The distance between them is the price of unviewable inventory, and it is the single most actionable number on this page for a display buy.

The formula.

The core identity is CPM = ad spend ÷ impressions × 1000, which the calculator rearranges two ways: ad spend = CPM × impressions ÷ 1000, and impressions = ad spend ÷ CPM × 1000. All three modes are algebraically the same statement, so they round-trip: $4,500 over 750,000 impressions gives a $6.00 CPM; $6.00 over 750,000 impressions gives back $4,500; and $4,500 at $6.00 gives back 750,000. The viewable branch first converts the viewability rate to a fraction and applies it to the impression count — 750,000 × 0.62 = 465,000 viewable impressions — then prices the same total spend against that smaller denominator: $4,500 ÷ 465,000 × 1000 = $9.6774…, displayed as $9.68. Equivalently, and identically to the last decimal, vCPM = CPM ÷ 0.62. Rounding stage matters here and is part of the contract: every intermediate value is carried at full decimal precision and rounding happens only once, at the return boundary — currency to two decimal places, impression counts to whole impressions. Nothing is rounded in between. That is why viewable CPM is computed from the unrounded CPM rather than from the $6.00 on screen. The difference is not cosmetic: a $1,000 buy over 300,000 impressions has a CPM of 3.33̅, which displays as $3.33, and a 50% viewability rate gives a true viewable CPM of 6.66̅ → $6.67. An implementation that doubled the displayed $3.33 would print $6.66 and be a cent wrong, and the test suite for this page asserts $6.67 specifically to catch that class of error. Guards reject the cases where the identity has no answer: impressions must be above zero whenever they sit in the denominator, the CPM rate must be above zero when you are solving for impressions, and the viewability rate must be above 0% and at most 100% — a 0% viewable buy has no viewable impressions to price, and viewable impressions can never exceed served impressions.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Interactive Advertising Bureau (IAB) — Glossary of Interactive Advertising Terms (Buyer's Certification Study Guide). Entries "CPM", "CPx pricing", "Cost Per Action (CPA)", "Cost Per Lead", "Impression" and "Click" (pp. 4–9). Retrieved 2026-07-29.
2. [2]Media Rating Council — Viewable Ad Impression Measurement Guidelines (Desktop), Version 2.0 (Final with 2015 additions), 18 August 2015. "Requirements for Viewable Display Advertising Impressions" (p. 4): ≥50% of pixels for ≥1 continuous second; large-format note (p. 5): 30% of pixels at ≥242,500 px; video requirement (p. 8): 2 continuous seconds. Retrieved 2026-07-29.
3. [3]MASB / Common Language in Marketing Project — Universal Marketing Dictionary, entry "Cost Per Thousand", quoting the American Marketing Association Dictionary (February 2015): "Cost per thousand impressions (CPM) ($) = Advertising cost ($) ÷ Impressions generated (in thousands)". Retrieved 2026-07-29.
4. [4]Farris, Paul W.; Bendle, Neil T.; Pfeifer, Phillip E.; Reibstein, David J. — Marketing Metrics: The Definitive Guide to Measuring Marketing Performance, 3rd ed., Pearson Education (ISBN 978-0-13-705829-7). Chapter 9, "Advertising Media and Web Metrics": §9.1 Impressions, §9.2 Cost per Thousand Impressions (CPM), §9.11 Cost per Click. Print reference — no free full text; edition, ISBN and section numbering verified against the publisher's sample-pages PDF.
5. [5]Google Ads Help — "Cost-per-thousand impressions (CPM): Definition": CPM bidding is "a way to bid where you pay per one thousand views (impressions) on the Google Display Network"; existing CPM bids convert to viewable CPM. Retrieved 2026-07-29.
6. [6]Google Ads Help — "Bid on viewable impressions using viewable CPM": with vCPM bidding "you set the highest amount you want to pay for each 1,000 viewable ad impressions"; Active View applies the Media Rating Council standard of at least 50% of the ad visible for at least 1 second. Retrieved 2026-07-29.
7. [7]Microsoft Learn / Xandr — Online Advertising and Ad Tech Glossary (document date 2025-10-22). Entry "CPM": "A pricing model in which advertisers pay for every 1000 impressions of their advertisement served. This is the standard basic pricing model for online advertising. See also CPC and CPA." Entry "vCPM": "Cost per mille, or thousand, viewable impressions." Entry "eCPM": "A translation from CPM, CPC, CPA, and any other pricing models so they can be compared." Retrieved 2026-07-29.