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Jun 19, 2008


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Morgan Stewart


I have attempted to evaluate the discrepancy of “real” opens versus the ones reported as “open rate” for a number of organizations. Based on about 20 cases that I have evaluated, the actual open rate is between 5% and 35% higher than what is reported--meaning that if the open rate from your ESP is 10%, then the actual open rate is between 10.5% and 13.5% (10% x 1.05 and 10% x 1.35)—assuming they use the “render rate” calculation.

Loren captured the primary drivers of the difference, but based on my analyses, the single biggest determinant of the difference is the design of the email. If the message is clear without images turned on, then the difference tends to be bigger.

So, how did I evaluate this? By looking at the differences in tracked opens (or “renders” as recommended by the EEC Measurement Roundtable). Brian V. highlights that his company adds clicks (for which no render was recorded) to renders in order to estimate the number of opens. That is what the EEC has proposed as “Actions” if you read the recommendations paper. While this does count more “opens”, unless the difference is made clear to the marketer looking at the metrics, it makes it impossible to perform the type of evaluation I performed.

If you want to look at how to calculate this yourself, check out this post: http://blog.exacttarget.com/blog/the-exacttarget-blog/0/0/how-much-does-open-rate-underestimate-actual-opens

Loren McDonald


Like everything in email the answer is "it depends." I'm not aware of any solid research or analysis that has pegged what the estimated open rate is versus what is measured. The other thing to keep in mind is the estimated open rate would vary based on several factors, including:

- Your subscriber base - are they B2B folks who use Outlook and typically scan emails in their preview panes with images not enabled? Or are they stay at home moms, who read the entire email with images enabled, etc?

- How does your email technology report opens? Some incorporate a click on a text message or HTML image without an actual open - as an open. The logic being, though the open tracking image did not load on the server, by the recipient clicking a link the "intent" was an open. Others only count an open when the tracking image loads on the server.

- Finally, the design and content of your emails. Image intensive emails are basically unreadable or actionable with images blocked - so the measured opens for these emails are probably pretty close to estimated or actual - because people have to enable images in order to read or take action. However an email that is designed to work well even with images blocked might have a significant difference between reported and actual or estimated.

But this is why the eec is working to move the industry away from the open rate to measures such as the render and action rate. The open rate is currently inaccurate and inconsistent. This is also why many of us (including some of the comments on this blog post) encourage email marketers to focus on achieving their business goals, and less on email metrics. At minimum, focusing on click-through rates over open rates is a good start.

Catherine Dazevedo

Do you have an idea of a figure of the discrepancy of real versus estimated open rate? "Way off" doesn't give me a sense of what you are tracking as a discrepancy. I understand that the figure is relative, but I continue to believe it is a solid metric, particularly if you are buying advertising into a third party newsletter -- it speaks to a (relative) interest level of the recipient. Thanks.


Again some great information coming from this blog. I wasn't aware of this on open rates, so I have certainly learnt something for the day- thanks again

Brian V.

Our company built a custom link tracker that allows us to track clicks by user. Anyone clicking a link is counted as an open. Total opens is calculated by combining traditional opens (image loads) with clicks...and that gets a bit closer to a more accurate number. Although we fully realize that it will never be accurate. Just another benchmark to use in the toolbelt.

Jim (Personalize Marketing) Ncp

Ya that’s the good thing, you have thought me the things which I was not knowing thank you

Adam Blitzer

Excellent post - I constantly encounter marketers who aren't aware of how open rates are calculated. I'll be posting this on my blog as well to help spread the "news."

Derrick Jones

Great work, I'll use what I've found here in my business...

Tamara Gielen

Ken, click-throughs are typically measured against either emails sent or emails delivered. I recommend you ask your contact at CC to tell you which formula they use to calculate click-throughs. Hope this answers your question?

Ken Burgin

OK - have to say I check my open and click-through rates on Constant Contact fairly regularly. So what proportion of actual click-throughs might the shown figure be?

Jim (Personalize Marketing) ncp

Thanks fpr your aricle...its very usefull...

Graham Jones - Internet Psychologist

Good advice. I am amazed at the obsession with open rates. The numbers of people who open or read your email is largely irrelevant; what matters most is the number that take action.

You could, for instance, have an open rate of 50% but an "action rate" of 5% of those who opened. In other words that would be a conversion rate of 2.5%. But what if you had an open rate of 20% yet an action rate of 50%. That would be a conversion of 10%. So the lower open rate is then better.

Open rates are not what you should be looking at - it's the numbers of people who do what you want them to do after they have read your email.

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