email marketing subject line length

I’ve spent years in the trenches of email marketing cranking out my fair share of messages. Hence, I’ve also done a heck of a lot of testing around the basics, including subject line length 60 characters. For years, we lived and breathed the golden rule of “keep your subject line to 40-50 characters.” Why? Most email browsers cut off anything longer, and that put the kibosh on your open rate.

Fast-forward to 2012 and a few things have evolved in the wild world of email marketing, including devices we use to read email, like mobile phones and tablets, and the emails we receive, like flash sales (which have the longest subject lines known to man). So, does your subject line length need to evolve too email clients? Let’s examine some facts first:

In a recent article on the EmailAudience blog, Jordie van Rijn cites a study from Adestra in which nearly a billion email marketing messages were analyzed. The study shows some thought-provoking results which vary pretty drastically between messages targeted at businesses (B2B) and consumers (B2C). According to the article and study, “in B2B emails, longer subject lines work better than shorter subject lines. Also when looking at the number of words. Subject lines with 6–10 words will drive open rates, but don’t deliver the clickthroughs. In the report 6-10 word subject lines are advised for awareness emails that don’t necessarily have a direct need for a call to action to click.

After 130 characters, there is a drop of the open rates, but also a huge increase in the number of clickthroughs. Anything over 16 words can deliver on both opens and clicks.”

And the study further notes, “The differences in B2C are much bigger than in B2B. Subject lines with 3-5 words appear to have a very bad effect on open and clickthrough rates. Subject lines with 3 or 4 words perform around 40% worse than average both in open rate and in clicks.

The subject lines with over 80 characters do hugely better in B2C email marketing. It seems to be that making your subject line stand out,
is ever important. A long subject line can do just that in B2C, with the added information and length to account for higher open and clickthrough rates. A 20-word subject line appears to be the real champion in this research, with a 115% uplift in opens and 85% uplift in clicks.”

Does this mean that all your B2B email subject lines should be long, and all your B2C emails should be 20 words? Nope. That would be far too easy, and it’s truly not all about how long or short your subject line is, but also about how targeted your email is to your audience. As with many things, one subject line length does not fit all, or even most. But, the good news is your subject line is one of the single fastest and easiest things you can test in an email.  

Inspired by daily deal sites and our own desire to provide more context, we recently began testing longer subject lines for our weekly VR Buzz newsletter. Like many of you, we struggle to pick just one topic from the newsletter we think will resonate with most of our readers. So, we started using longer subject lines like the following:


In this example, we made the subject line longer (using about 67 characters) and included 2 topics vs. just one, as we’d done in the past. Over a nine-week period, we saw about a 1% improvement in open rates from our most engaged subscribers. This isn’t earth-shattering, but what’s interesting is that it led to a marked improvement in our CTRs (clickthrough rates) – an improvement of nearly a percent and a half. To make things really interesting, the longer, multi-topic subject line newsletters also produced significantly higher revenue (ca-ching!). So, what seems to be hitting the mark for us, is not just the length, but also the multi-topic inclusion.

In the world of email marketing, the subject line is one of the most crucial elements. The length of the subject line can greatly impact the success of your email marketing campaigns. While there is no one-size-fits-all answer to the ideal length of an email marketing subject line, it is generally recommended to keep it within 50-70 characters long. This length is optimal for being fully displayed on most desktop and mobile devices. By following email subject line best practices, including keeping the length of the subject line within the recommended range, you can improve your chances of having higher open rates and getting your subscribers to actually open your email marketing subject line length.

How can you make your subject lines hit the target with your readers? It might be time to try multi-topic subject lines or to test out the length. Longer may be better for the new iPhone 5, but will it get results for your subject line?

© 2012 – 2018, Contributing Author. All rights reserved.

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