How you can Optimize Your Electronic mail Topic Line Size


8 minutes reading time

Campaign Monitor – December 2, 2021

As a marketer, you work hard to write great copy and create compelling emails. However, if you don’t include subject lines that encourage subscribers to read your messages, your campaigns can fall short.

More and more emails are opened on mobile devices, which typically have fewer characters. With that in mind, you might be wondering if your subject lines should be shorter to help keep subscribers on the go.

Is there a secret to the perfect length of the subject line?

Every subscriber list is different, so the perfect subject line length depends on a variety of factors. But it is possible to get a glimpse of the ideal lengths for your industry. Take advantage of these insights and you are sure to see more engagement and performance in your marketing emails.

In this post, we share some actionable tips to help you determine the correct email subject line length for your email marketing strategy.

Factors to Consider When Determining the Length of the Email Subject Line

There really is no one-size-fits-all length. In fact, the ideal length of your subject line depends on a variety of factors.

1. The devices and clients on which your e-mails are read

The number of emails opened on mobile devices has increased dramatically over the past decade. In 2021, 41.6% of total openings were on mobile devices. But somehow 1 in 5 emails sent is still not optimized for mobile devices.

While optimizing for mobile has more to do with the code or template you use, it also has an impact on your subject line. Different devices truncate your subject lines differently, and if you don’t test for them, you can end up with some painfully uncomfortable results.

Fortunately, Campaign Monitor’s Inbox Preview lets you preview your email in over 25 different email clients before sending your campaign to ensure your email looks great in every inbox.

Screenshot of the design of the campaign monitor and spam test

When considering the length of the subject line that works best for your marketing emails, consider using data to locate subscriber devices. Do most of your subscribers open emails on their phones or do they stay on their desktop?

Campaign Monitor users can easily find this information in their Campaign Monitor account in the Campaign Reports section under Email Client Usage. This will help you optimize the length of your subject line.

Here are some stats for the top 10 email devices and clients for 2021, including market share:

Email customer data for 2021.

Image source

Since most people view email on iPhones and Gmail, optimize the subject line length from 41 characters (portrait view on an iPhone) to 70 characters for Gmail. You don’t want an interrupted experience because your subject line is too long.

2. How the previous subject lines have cut off

It’s also a good idea to look at which subject lines in your past emails resulted in high open rates.

High open rates can occur due to offers you were offered, the time of day, or the text and sentiment in the subject line itself.

Still, it’s worth taking a look to see if your email open rates and subject line length are trending.

So what’s the optimal email subject line length?

According to a study by Marketo, 41 characters or 7 words, seems to be an ideal point for the email subject line length, which is about 10 characters less than the average subject line.

Subject line length


Here are a few email subject lines paired with their character length to give you an idea of ​​what a 41-character subject line looks like:

Email subject line

Number of characters

Work can wait – these sales are SO good 41
Make a meatless bread that even meat lovers will love 47
Cyber ​​Monday for those procrastinators 38
7 habits that will make you a leader that your colleagues want to be 65
5 SEO trends for 2019 | Mobile vs. desktop search | Profit / Loss Analysis | SME expectations 88

When creating your email subject lines, keep in mind when and how your subscribers will read your email.

If most of the openings are on iPhones, consider using shorter email subject lines for the greatest impact. Also, put your offer or CTA at the beginning of your subject line where it’s most likely to be seen. You can also use pre-header text to add more context to your subject lines in the preview area.

Email subject line

9 Email Subject Line Best Practices

Finding the ideal length for a subject line is an important step in your email marketing, but subject lines are not all about length. To be successful, you must use general best practices.

1. Use different subject lines

Using the same subject line over and over again won’t delight your subscribers. So instead of using the “January 2021 Company Newsletter,” try to get more creative and encourage subscribers to open emails and see the latest and greatest information that you have to offer.

2. Keep the subject lines short

Short subject lines tend to take hold. As mentioned earlier, research has shown that around 41 characters is the optimal length for a subject line. Still, some marketers suggest going even shorter.

Backlinko founder Brian Dean says subject lines that don’t exceed 16 characters on average have significantly higher open rates. He attributes this to two factors.

First, emails with shorter subject lines are more likely to be delivered. Second, brevity creates a mysterious atmosphere.

Per Dean thought the subject line, “Are you available for a meeting today at 11?” (38 characters) does not have quite the same effect as “Meet at 11?” (14 characters).

All in all, keep your character count down if you can. It might also be a wise decision to put character restrictions on people who send email in your company.

3. Test your subject lines on all devices and clients

As mentioned earlier, you should make sure that your subject lines display correctly on all devices. Sending test emails will help you make sure your subject line is legible everywhere.

4. Take into account your case-sensitive style

While you might not think much about how to capitalize your email subject lines, it should be! There are four basic styles:

  • How to write an email subject line (sentence case)
  • How to Write an Email Subject Line (Title Case)
  • How to write an email subject line (all lowercase)

Some marketers like Val Geisler attribute increased open rates to a looser, more personal atmosphere. In this case, you can choose upper / lower case or all lower case for your subject lines.

5. Use personalization

Take advantage of the personalization right in the subject line by including subscriber names. You can use many other personalization options based on subscriber data. This data can be collected through your registration form or from other sources such as Shopify or OptinMonster.

Email subject line best practices

Image source

This is a meaningful subject line because it is short, asks a question, and ties in with previous recipient behavior. Consider doing the same with your email.

6. A / B test subject lines

You’ll never know what works best without trying different options, so test your subject lines A / B to find the best one. You can A / B tests of different lengths and different types of copies to get a good idea of ​​what your email list is responding to.

Email subject line formula

7. Use emojis when appropriate

While the debate about emojis continues, the fact is that they are here to stay. Their judicious use of subject lines can make your email stand out in an inbox with seemingly endless lines of stacked text.

Emojis have other advantages. The majority of businesses don’t use them, and this can contribute to a higher response rate for emails that use them. They also create powerful emotional storytelling, perfect for those shorter lines of text on mobile devices.

8. Avoid spam filters

Every email that ends up in a spam folder is a missed opportunity for an open, click, and sell conversion. For this reason, according to Yesware’s extensive research, you want to avoid using the following words in subject lines.

Length of the email subject line in 2018

Avoiding spam filters means more than just the choice of words. (Using all capital letters will get you there too.) No matter what, delete the above spam words and phrases from your subject lines.

9. Use automation

While this isn’t entirely related to subject lines, it’s worth noting that using automation in your email strategy will increase your engagement metrics. Even simple automation steps like a welcome trip are effective ways to get your subscriber list at the time when they are most engaged.

If you can play off the timing or context of your automated email in your subject lines, your results will only get better.

Wrap up

Ultimately, the best email subject line length varies from brand to brand. That said, it’s best to try different lengths to see what works for you.

By using your past data and testing your subject lines, you already know how long email subject lines should be to encourage subscribers to open up your campaigns and take action.

For more tips on writing email subject lines, see our post on subject line best practices.

Related link: Niche Marketing Kit

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