**This post has been updated as of February 2019**
As a marketer, you work hard to write great copy and create compelling emails. But if you aren’t writing subject lines that encourage subscribers to read your messages, your campaigns could fall short.
More and more emails are opened on mobile devices, which typically show fewer subject line characters. With this in mind, you may wonder if your subject lines should be shorter to accommodate on-the-go subscribers.
Is there a secret to the perfect subject line length?
Every subscriber list is different, so the perfect subject line length depends on a variety of factors. But it’s possible to get insight into ideal lengths for your industry.
In this post, we’ll share some actionable tips for finding the correct email subject line length for your campaigns.
Factors to consider in your email subject line length
There’s really no such thing as a one-size-fits-all length. In fact, the ideal length of your subject line depends on a variety of factors.
1. What devices and clients your emails are read on
From 2011 to 2018, email opens on mobile devices increased by 34%. In 2018, 61% of emails were opened on a mobile device.
It’s also important to keep in mind that your subscribers use a variety of different browsers and email clients. This further contributes to the complexity of having a one-size-fits-all optimal subject line length.
This chart shows the number of characters that display across common devices and clients:
When considering the email subject line length that will work best for your campaigns, consider using data to pinpoint subscriber devices. Are most of your subscribers opening emails on mobile, or are they sticking to their desktop?
Pro-tip for CM users: You can easily find this information in your Campaign Monitor account, in the Campaign Reports section under Email Client Usage. This will help you optimize your subject line length.
Here are January 2019 statistics for the top 10 email devices and client including market share:
Since most people are viewing emails on iPhones and Gmail, optimize your subject line length to between 41 characters (portrait view on an iPhone) to 70 characters for Gmail. (You don’t want a broken experience because your subject line is too long.)
2. Past email subject line performance
It’s also a good idea to look at which subject lines have garnered high open rates in your past emails.
High open rates can occur because of deals you were offering, the time of day, or the copy and sentiment in the subject line itself.
Still, it’s worthwhile to take a look and see if any trends emerge from your email open rates and the length of the subject line.
How many characters are optimal?
According to data from Marketo, 41 characters–or 7 words–seems to be a sweet spot for email subject line length in 2019, which is about 10 characters less than the average subject line.
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 | Character Count |
| Work Can Wait – These Sales are THAT Good | 41 |
| Make a Meatless Loaf Even Meat Lovers Will Love | 47 |
| Cyber Monday For Those Procrastinators | 38 |
| 7 Habits That’ll Make You the Leader Your Colleagues Aspire to Be | 65 |
| 5 SEO Trends for 2019 | Mobile vs. Desktop Search | Win/Loss Analysis | SMB Expectations | 88 |
As you craft your email subject lines, remember when and how your subscribers are reading your emails.
If the majority of the opens are happening on iPhones, you’ll want to use shorter email subject lines to get the most impact. Additionally, keep your offer or CTA at the beginning of your subject line where it’s most likely to be seen. You can also use preheader text to add more context to your subject lines in the preview pane.
Testing your email subject lines
Your email subject line is one of the single easiest elements to test in your email campaign. Tests can help you see how your email subject lines will look across devices, as well as how they compare to shorter or longer versions.
- Send test emails to see how subject lines render on all devices. This will ensure your subject line reads well anywhere. Our Inbox Preview feature enables you to see previews of your email in over 25 different email clients before sending your campaign to ensure your email looks great in any inbox.
- A/B test two different lengths. Certain email providers allow you to A/B test two different subject lines to see how they perform. Try testing a short and long version to see which performs better.
Leverage 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 just about length. In order to see success, you’ll need to leverage general best practices. Remember to:
- Use different subject lines. If you use the same subject line over and over, it won’t excite your subscribers. New subject lines encourage subscribers to open emails to see the latest and greatest information you have to offer.
- Use personalization. Use 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 sign-up form or from other sources like Shopify or OptinMonster.
- A/B test subject lines. You’ll never know what works best without trying different options, so test your subject lines to find the best one.
Optimal length for email subject lines in 2019
Email marketing continues to provide the best return on investment (ROI) versus other marketing channels in 2019. This success still begins with a short, well-crafted subject line compelling the recipient to open it.
5 email subject line best practices in 2019
While the length of email subject lines is still critical in 2019, how you use the characters allowed in a line of text is more important than ever. This is especially true with the truncated display–30-40 characters–on most mobile device screens.
1. Shorter subject lines: As discussed above, research shows around 41 characters is the optimal length for a subject line. Still, some marketing experts suggest going even shorter.
Backlinko founder Brian Dean says subject lines which on average do not exceed 16 characters 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 an air of mystery.
Per Dean’s thinking, the subject line “Are you available to meet today at 11?” (38 characters) doesn’t have quite the same impact as “Meeting at 11?” (14 characters).
2. Emojis: While the debate about emojis continues, the fact is they’re here to stay. Their judicious use in subject lines can set your emails apart in an inbox with seemingly endless stacked lines of text.
There are additional advantages provided by emojis. A majority of companies do not use them, and this may contribute to the higher response rate for emails which employ them. Plus, they create powerful emotive storytelling, perfect for the shorter lines of text on mobile devices.
3. Capitalization: While you may not be giving much thought to how you’re capitalizing your email subject lines, you 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)
- HOW TO WRITE AN EMAIL SUBJECT LINE (all uppercase)
The pie chart below shows how often marketing professionals use each of these styles.
There are two important takeaways here. First, zero percent of marketing professionals use all uppercase capitalization for subject lines.
Second, despite lowercase capitalization only being used 6% of the time, some marketing experts such as Val Geisler attribute increased open rates to it due to a more casual, personal feel.
4. Personalize: Using the personal touch in subject lines such as including the recipient’s name is a standard technique to increase open rates. You can, however, based on individual website page views or search terms, use other types of personalization.
This is a powerful subject line because it’s short, asks a question, and ties to previous recipient behavior. Consider doing the same with your emails.
5. Avoid spam filters: Every email which winds up in a spam folder is a missed opportunity for an open, clickthrough, and sales conversion. That’s why, according to extensive research was done by Yesware, you want to avoid using the following words in subject lines.
There’s more to avoiding spam filters than word choice alone. (Using all capital letters will take you there, too.) No matter what, delete the above words and phrases from your subject lines.
Wrap up
At the end of the day, the best email subject line length will vary from brand to brand. That means it’s best to test out different lengths to see what works for you.
If you leverage your past data and test your subject lines, you’ll be well on your way to knowing how long email subject lines should be to encourage subscribers to open and take action with your campaigns.
For more tips on writing email subject lines, check out our guide to 15 powerful subject line words.
**This post was originally published December 2015**
