Adviso has just conducted some research about ideal email width, and here are the main points of the article published on the blog, translated in English for your convenience. Of course, every agency and webdesigner has at least once been confronted to that question: how wide should my newsletter be? That’s a very good question, because a few more or less pixels can change a lot, and display a horrible horizontal scrollbar on your beautiful content! Anyone can find a lot of figures on Internet, and it is quite easy to find that an email width should be between 500 and 700 pixels. A few months ago, I published another article on Adviso’s blog, with 12 best practices for email newsletters, based on Norman & Nielsen Group’s Email Newsletter Usability Report. Knowing the exact optimal size of a newsletter was the next step!

Image: Email on Acid test interface screen capture

Methodology

We didn’t actually test every email size possible in every existing email solution, online and offline. We didn’t, because a very useful online tool, named Email on Acid allowed us to do so in a very simpler way. This entirely free and very intuitive tool allows you to watch a newsletter as it will be displayed by the main email services, both on and off line. For every email service, 3 data were then compared:

• the size of the main content column,
• email services market shares,
• main screen resolutions market shares.

Nb: the main limit of the obtained results is that it is possible to resize and personalize the content columns in almost every email service. Though, a test between Email on Acid data and default widths of 3 major email services showed an insignificant difference.

Results: 530 pixels to reach everyone

The following table shows main content column widths (in pixels) for all 9 main email services considered, both with a screen resolution of 1 024 pixels and 1 280 pixels wide. The email services are sorted by market shares (in %), starting with the most popular one.

We can see that the most little widths, 534 and 723 pixels, are always displayed by Gmail, which only has a 6% market share. Gmail is followed by AOL AIM Mail, with 577 and 776 pixels. We can also see that the widths vary a lot, between Gmail’s 534 pixels, with a 1 024*768 resolution, and Entourage’s 773 pixels with the same resolution.

As always, a picture is worth a thousand words: the graph below sums up all the obtained results in one image. It takes into account both 1 024 and 1 280 screen resolutions and their market share, as well as email services market shares, to show what is the part of readers we can reach according to the email width.

It’s very clear to see that the maximal width to use in order to be sure to reach all readers is 530 pixels. Otherwise, choosing 620 pixels can be wiser, as it allows to reach up to 80% readers, without sacrificing design space too much: according to email services market shares, it is totally possible to ignore some of them, to gain up to 100 pixels. So, what to do? Adviso advises to start with a 530 pixels width. Then, always be testing (© Future Now) applies to your newsletter too! Go on your Google Analytics, and check how many of your visitors actually use a 1 024*768 screen resolution, then adapt to your readers!

Limits

Please keep in mind that this study was conducted « on the field »: widths are based upon screen captures (a variation of 1 or 2 pixels could be observed). Also, screen resolutions and email services market shares are going to change rapidly, and so these results should be updated in a short time. Again, the main limit of this study is that readers can personalize the layout of their email service.