eCPM calculator for publishers.

What an eCPM calculator tells you

An eCPM calculator turns your ad revenue and impressions into one rate: what you earned for every 1,000 ads shown. That's the number you use to compare ad units, countries and demand partners on equal terms. Google's AdMob help page on effective CPM calls it an estimate of the revenue you receive for every thousand impressions.

The "e" stands for effective. A CPM is a price someone bids. An eCPM is what you actually got after every auction, every unsold slot and every cheap impression is mixed in. So it's a result, not a price list. Keep that in mind and the rest of this guide gets a lot easier.

This page sits next to our longer explainer on what eCPM means for publishers. Here we stick to the maths and how to use it on your own reports.

How to calculate eCPM, step by step

To calculate eCPM, divide revenue by impressions and multiply by 1,000. That's it. The hard part is picking the right revenue and the right impressions.

1. Pick one date range. Revenue and impressions must cover exactly the same days.
2. Pick one scope. One ad unit, one country or one demand source. Or the whole site, if that's what you're checking.
3. Use impressions, not requests. Unfilled requests aren't impressions, so they don't belong in the sum.
4. Use the same currency. Mixing dollars and euros gives you a rate that means nothing.
5. Divide, then multiply by 1,000. Or type both numbers into the calculator above.

The eCPM formula, three ways round

The same formula answers three different questions. Our calculator solves whichever one you leave blank.

The third row is the one people forget. If you want $1,000 a month and your eCPM is $2, you need 500,000 impressions. That tells you whether to chase traffic or a better rate.

eCPM vs CPM vs page RPM

eCPM is per 1,000 impressions you earned from. CPM is per 1,000 impressions at the price a buyer agreed. Page RPM is per 1,000 page views. They sound alike, but they answer different questions.

Google gives the page version on its AdSense RPM page: estimated earnings divided by page views, times 1,000. Add page views to the calculator and you'll see both rates side by side.

Why page RPM is usually higher

Each page view can show several ads. With 2.5 ads per page, $450 from 300,000 impressions is a $1.50 eCPM but a $3.75 page RPM. Nothing changed except the thing you divide by. If two reports disagree, check which one you're reading before you worry.

How to use the eCPM calculator with your reports

You'll get the cleanest answer by taking revenue and impressions from the same report. Here's where each platform keeps them.

If the platform already shows eCPM, why use a calculator? Because it won't blend sources for you. Once you add AdSense, AdX and a few header bidders together, the only honest total is one you work out yourself.

Blend eCPM across sources the right way

Never average two eCPMs. Add up the revenue, add up the impressions, then divide. A simple average gives a small source the same weight as a big one.

The gap here is 25 cents per 1,000. On a few million impressions a month, that's the difference between a good month and a confusing one. Put the totals into the calculator and it does the blending for you.

When a higher eCPM means less money

eCPM can rise while revenue falls. It only counts impressions that sold, so anything that cuts weak impressions pushes the rate up, even if you sell fewer ads.

Here's a common case. You raise a price floor. Before, you sold 300,000 impressions at a $1.50 eCPM for $450. After, you sell 180,000 at $2.10 for $378. The rate looks 40% better. You've lost $72. Google says Ad Manager picks the winner by the highest net bid, so a floor set above what most buyers bid simply leaves slots empty.

So read three numbers together: eCPM, fill rate and total revenue. Our ad revenue calculator puts eCPM and fill into one monthly figure, which makes this trade easy to see.

What moves your eCPM

Your eCPM rises when more buyers compete for each impression and when those impressions are worth more to them. Most of the levers fall into a handful of groups.

• Competition. More demand sources bidding at once means a higher winning bid. That's the whole point of header bidding and of AdX access.
• Viewability. Ad Manager counts a display ad as viewable when half its pixels show for one continuous second, per its viewability overview. Buyers pay more for ads people see.
• Ad size and format. Sizes with lots of demand fill better. Our guide to banner ad sizes covers which ones.
• Audience and country. Buyers bid more in some markets and on some devices. Always check eCPM by country before judging a change.
• Time of year. Ad budgets change through the year, so compare a month with the same month last year when you can.
• Page speed and layout. Slow, crowded pages lose viewability, and that pulls the rate down on every unit.

How to raise eCPM without losing revenue

Change one thing at a time, measure revenue per 1,000 page views, and keep the change only if the total goes up. Here's a safe order to work in.

1. Fix viewability first. Move units that sit below the fold on long pages and lazy load the rest.
2. Trim sizes nobody bids on, and keep the few that fill well.
3. Add demand. More bidders in a fair auction usually beat any floor trick.
4. Set floors from data, per country and device, and lower them if fill drops sharply.
5. Check the result with page RPM, not eCPM alone.

If you'd like a second pair of eyes, our reporting and yield team checks eCPM, fill and viewability together. The first review is free.

eCPM calculator mistakes to avoid

• Mixing date ranges. Revenue from last month and impressions from this month gives a made-up rate.
• Using ad requests. Requests include slots that never filled. Use impressions.
• Averaging rates. Blend totals instead, as shown above.
• Trusting a single day. Daily rates jump around. Look at a week or more.
• Judging on eCPM alone. Revenue pays the bills, not the rate.