How do you calculate CPM?

Divide total spend by impressions, then multiply by 1,000. Spending $450 for 90,000 impressions gives a CPM of $5.00.

What does the M in CPM stand for?

The Roman numeral for one thousand — so CPM is cost per thousand impressions, not cost per million. It's the most common misunderstanding of the term.

Is CPM better than CPC?

They suit different goals. CPM fits awareness campaigns where being seen is the point; CPC fits campaigns that need clicks, because you only pay when someone reacts.

How do I convert CPM to CPC?

Divide spend by clicks, where clicks = impressions × CTR. A $5 CPM at 1% CTR gives an effective CPC of $0.50; at 2% CTR it drops to $0.25.

CPM Calculator – Cost Per 1000 Impressions

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CPM Calculator Guide

CPM is what you pay for a thousand ad impressions. The M is the Roman numeral for a thousand, not "million" — which is the single most common misunderstanding of the term. This CPM calculator works it out from spend and impressions, or runs backwards from a rate card.

The Formula

CPM = (Total spend ÷ Impressions) × 1,000
Spend $450 for 90,000 impressions and your CPM is $5.00.

When CPM Makes Sense

CPM buying suits awareness campaigns, where the goal is being seen rather than clicked. If you're launching a brand or running video, paying for reach can be reasonable. If you need leads or sales, CPC or conversion-based buying usually fits better, because with CPM you pay whether or not anyone reacts.

CPM vs CPC

They're two ways of pricing the same traffic, and you can convert between them if you know your click-through rate.

A $5 CPM with a 1% CTR means 90,000 impressions produce 900 clicks for $450 — an effective CPC of $0.50. Raise the CTR to 2% and the same CPM halves your effective CPC to $0.25. That's why creative quality matters so much on CPM buys: better ads make the same rate card cheaper.

Impressions Are Not People

This trips up a lot of reporting. Impressions count ad views, not viewers. One person seeing your ad ten times is ten impressions. That's what frequency measures, and high frequency on a small audience is how budgets get burned annoying the same people repeatedly.

Viewability Matters

An impression can be counted for an ad that scrolled past below the fold. Viewability standards exist for exactly this reason. A cheap CPM on unviewable inventory isn't cheap — it's free money for somebody else.

Working Backwards From a Budget

If a publisher quotes an $8 CPM and you have $600, that's 75,000 impressions. Switch this calculator to "Impressions I can buy" to run that in either direction before you sign anything.

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