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How Long Should Subject Lines Be? Discover the Key to Boosting Open Rates

The length of your subject line can be the difference between floating to the top or sinking unseen. A few characters too long or too short, and your message might miss its mark. But why is optimizing subject line length so crucial, and how can it significantly impact your email’s success? Dive into this article, and you’ll uncover the science and strategy behind crafting the ideal subject line length that not only grab attention but also drive engagement.

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The Optimal Subject Line Length (+ Subject Line Tips)

Crafting perfect email subject lines are both an art and a science. It’s the first impression your email makes, and in an era where inboxes are inundated daily, standing out is paramount. Several factors determine the optimal subject line length, including its effectiveness, email system constraints, and the device’s display size. These variables can vary, affecting the desired length.

The best email subject line length, as research suggests, are concise with the ideal length being no more than nine words and 60 characters. But why is this the case? Let’s delve into the findings and insights from industry experts to understand these recommendations for the perfect subject line.

1. The Numbers Game

On average, email subject lines hover around the 40-60 character mark. According to a study by Marketo, the optimal subject line is 41 characters or 7 words. The most common length is between 41 and 50 characters. However, it’s essential to note that while these are averages, the optimal length can vary based on your specific audience and the content of your email.

When writing subject lines, start with your complete message and then streamline by removing or changing words. Take, for instance, the subject line “Exclusive Preview: Summer Collection Launches Tomorrow!” which has 56 characters. To make it more concise, you could revise it to “Summer Collection Preview Tomorrow!” This revised version retains the core message but reduces the character count to 39, making it more succinct and mobile-friendly. Such adjustments ensure that your email subject lines are impactful while fitting within the character constraints of various email platforms.

2. Mobile vs. Desktop Considerations

With a significant portion of users checking emails on mobile devices, there’s limited screen real estate to work with. It’s important to get to the point quickly, ensuring that even if a user only sees the first few words of a subject line, they grasp the core benefit.

The device your audience uses to read their emails can significantly influence subject line visibility. While desktops might display up to 60 characters, mobile devices, which are increasingly popular for checking emails, often show only around 30-40 characters. This means that if your subject line is too long, mobile users might miss out on your message as it will become a truncated subject line.

On mobile devices, most email clients like Gmail and Yahoo! typically display email subject lines only up to 33 to 43 characters. The exact limit varies by client. Ensure your key message or offer is conveyed within this range.

Subject Line Example: “Summer Sale: Get Your Beach Essentials Now!” (On mobile, this might appear as “Summer Sale: Get Your Beach…”)

3. The Power of Brevity

While conveying your message is essential, something must be said about the allure of shorter subject lines. Brian Dean of Backlinko, previously sent emails with detailed, longer subject lines. However, he has since experimented with shorter ones, shifting from explicitly describing the email’s content to a more concise approach. Eventually, he found that subject lines averaging around 15.1 characters had higher open rates. The succinctness or short subject lines can create a sense of mystery, prompting curiosity-driven opens.

Subject Line Example: “New Launch!” (11 characters)

4. Test Your Subject Lines

While these guidelines provide a starting point, understanding your unique audience is the real answer. Test subject lines to see which lengths resonate with your specific audience. A/B Testing is a powerful method to determine the most effective subject line for your audience. By sending two subject line variations to different segments of your audience, you can directly compare which one performs better in terms of open rates. 

An increase in open rates is a direct indicator of the effectiveness of your subject line. If one variation consistently outperforms the other in terms of open rates, it’s a clear sign of what resonates more with your audience.

Continuously run A/B tests of different subject lines lengths and analyzing the open rates. This can offer insights into your email campaign tailored to your subscribers. Try short and long email subject lines with your subscribers to see what works best for your unique audience.

Once you’ve gathered data from your tests, it’s essential to iterate. Use the insights gained to refine your approach to using different lengths, and don’t hesitate to test again. The email landscape is ever-evolving, and what works today might need adjustment tomorrow.

Subject Line Example: For a holiday promotion, you could test “Huge Christmas Sale: 50% Off!” against “Christmas Sale!”

5. Consider Email Providers

Different email platforms have varying display limits. For instance, Gmail might show up to 70 characters, but Yahoo! Mail might display only 46. Being aware of these nuances can help in crafting universally effective subject lines.

While there are general guidelines and best practices for email subject line lengths, the optimal length is the one that resonates with your specific audience. Regular testing, staying updated with industry trends, and understanding your audience’s preferences will ensure your subject lines always hit the mark.

6. Show Off The Benefits Early

Avoid generic subject lines that are popular but lack a specific hook. Emphasize the advantages of your promotions and spotlight particular deals. When you lead with the benefits, recipients can instantly recognize the value of opening your email. Subject lines that clearly convey a benefit or offer tend to have higher open rates.

For optimal readability, especially on mobile devices, keep subject lines concise, ideally under 9 words and 60 characters. Research also suggests limiting punctuation to a maximum of 3 marks per subject line. Too many punctuation marks can make your emails and subject lines appear spammy or even get targeted by spam filters.

A benefit-driven subject line not only informs but also entices the recipient to take action. Whether it’s availing a limited-time offer or gaining access to exclusive content, the promise of a benefit can drive clicks.

Subject Line Example: “Join Now & Get First Month Free!”


7. Preview Before Sending

There are dedicated email subject line analyzers available that can provide insights into the effectiveness of your subject line. These tools evaluate various factors such as character count, word choice, and potential spam triggers. By using them, you can refine your subject lines to be more engaging and less likely to be flagged as spam.

Ensure your emails avoid the spam folder by carefully crafting your subject lines. Utilize an email subject line analyzer to assess character count and word choice. Additionally, send test emails to preview how they appear across various devices and email clients.

Different email clients and devices can display subject lines differently. What looks perfect on a desktop Gmail interface might be truncated on a mobile Apple Mail display. By sending test emails, you can preview how your subject line appears across a range of devices and email clients. This ensures that your core message remains intact and compelling, regardless of where it’s viewed.

Wrapping Up: The Art and Science of Email Subject Lines

While research provides us with general guidelines, such as aiming for no more than nine words or 60 characters, the true magic lies in tailoring your approach to your unique audience. Whether you’re considering the device they use, the email provider they prefer, or the benefits they seek, each element plays a crucial role in determining the success of your email campaigns.

Remember, while brevity and clarity are essential, it’s the resonance with your audience that truly counts. Regular testing and adaptation, combined with a keen understanding of industry trends and audience preferences, will ensure your email subject lines not only capture attention but also drive meaningful engagement. As you continue your email marketing journey, let these insights guide you, but always let your audience’s response be the ultimate compass.