Resources Hub » Knowledge base » What Is The Ideal Length Of An Email Subject Line?

Creating a high-quality, effective email campaign takes a lot of planning. From the design of the email to crafting the subject line, preheader text, and the content, there are so many moving parts that it can be hard to remember it all.

Breaking down the email design process makes it easier to focus on each aspect of your campaign.

What’s the best place to start? The email subject line.

What is an email subject line?

An email subject line is the very first piece of information that readers will see once they open their inbox. While that small line of text may seem insignificant at first glance, it’s a vital piece of email anatomy that can make or break your campaign’s overall success.

Every email subject line needs to contain the topic of the email, written in such a manner that the reader is compelled to open it up. If they don’t feel enticed to do so, the email won’t be opened, read, and may end up going straight in the trash folder.

How do you measure the success of your email subject line?

Measuring the overall success of your email subject line can be done in several ways. However, the most common methods include monitoring the campaign’s open rate, click-to-open rate, and click-through rate.

This also requires knowing what your brand’s average is. You can compare your email metrics to these industry averages.

Open rate

An email open rate is the calculated percentage of subscribers who’ve taken the time to open up your email. On average, a good open rate is typically in the range of 20-40%, and can be calculated with the following formula:

Open Rate = (Total # of emails opened ÷ total # of emails delivered) x 100

Click-to-open rate

Contrary to popular belief, the open rate and click-to-open rate aren’t the same figures. The click-to-open rate (CTOR) compares the number of total unique clicks and the total number of unique opens an email receives. On average, a healthy CTOR will vary between 20-30% and can be calculated with the following formula:

CTOR = (# of unique clicks ÷ # of unique opens) x 100

Click-through rate

Your click-through rate is the overall measurement of how many of your recipients clicked on a hyperlink, CTA, image, or video within your email. A healthy click-through rate (CTR) falls around 15% and can be calculated with the following formula:

CTR = (Total # of unique clicks ÷ total # of delivered emails) x 100

Does the email subject line really matter?

Yes! Countless studies have been done to answer this question, and the results speak for themselves. Subscribers react better to subject lines that vary in length.

What is the ideal length of an email subject line?

What words perform better than others? While this is a common question, many researchers have stated that focusing on the words matters more when it comes to the total number of characters used.

Why characters instead of words? Different email clients show a varying number of characters when it comes to both mobile and desktop views.

Why characters instead of words? Different email clients show a varying number of characters when it comes to both mobile and desktop views.

Source: Campaign Monitor

Knowing the ideal character count for your email subject lines will help you better narrow down which words will help your readers feel more compelled to open your messages.

What now?

Now that you understand what an ideal length is for your email subject line should be, it’s time to become an email subject line superhero. Our guide will not only help you identify excellent word choices and email subject line lengths, but it’ll also help you break down the many different types of email subject lines available to you.

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.

Get started with Campaign Monitor today.

With our powerful yet easy-to-use tools, it's never been easier to make an impact with email marketing.

Try it for free