Increase Your Email Open Rates By 50% With These 9 Subject Line Formulas

Your email marketing strategy faces some tough challenges. According to the Radicati Group’s comprehensive study, the average business user gets more than 120 emails per day, and almost half of them are never opened.

Like any marketing strategy, it’s a numbers game. Your email open rate is affected by many statistical factors: time of day, species of browser or device, and personal preferences, to name just a few.

Some of these factors are out of your control, but there are things you can do to improve your odds of success dramatically.

Your subject line is the most vital part of any email you send out. Based on that single line of text, potential customers will either open and hopefully click through to your site, or ignore your email. Creating an irresistible line of text for your email’s subject is a huge factor.

With the above in mind, this post will reveal nine proven formulas for creating subject lines that stand out from the crowd and can increase your email open rates by as much as 50%.

Let’s get right into it.

1. The Shocking Or Unusual Subject Line

We all enjoy pleasant surprises, so an email that makes you chuckle and piques your curiosity is bound to encourage you to open the message.

These subject lines are curiosity-driven and compel people to stop, wonder what you could possibly be talking about, and open your email to find out.


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2. The Social Proof Strategy Subject Line

The fact that something is widely accepted or adopted, especially by those in the know, can create temptation to “follow the crowd.”

For more information on why social proof is so effective, and how to utilize it effectively, check out this fantastic Kissmetrics article.


  • Find Out Who Else is Using [Your Great Product]
  • Learn How the 100 Top Businessmen Benefited from [Your Service]
  • Successful Online Entrepreneurs in [Client’s Location] Use This Strategy to Increase Productivity

3. The Odd Numbered List Subject Line

Fact: numbered lists are opened far more than equivalent subject lines without numbers.

Strangely enough, odd numbers work slightly better than even numbers, according to the Content Marketing Institute and Outbrain. Add these to your email subject lines and watch your open rates increase.


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4. The Personal Touch Subject Line

Including a client’s personal name builds rapport and encourages engagement. That said, it’s not always possible. Many people are hesitant to give out their real names online and mass mail lists are fraught with data errors.

Instead, take the lead by being candid yourself. Adding your personal name and your company’s name is a winning strategy, according to Forbes. Location-specific messages are also significantly more effective than general ones.

When opening an email, most of us prefer knowing exactly where the email came from, and what the message is about. Craft your subject line (and your message) in a personal way. Avoid misleading people or hiding your objective, because that’s the quickest way to alienate them. Honesty is the best policy!


  • Hey [Client Name], I’m [Your First Name] from [Company], and I’d Like to Introduce You to [Product]
  • [Name] from [Company] Explains Why You Need to Consider the Benefits of [Product]
  • Your Online Business Could Double Its Income with [Company’s] Software

5. The Announcement and Invitation Subject Line

Readers want the latest, freshest information; nobody wants to be left behind. As such, including the idea in your subject line that your email is “breaking news” will make it more likely to be read.

People enjoy invitations. It gives you the feeling that you’re free to decline if you want to. Inviting someone to “be the first to” do something, or find the answer to a perplexing question, is another angle on the same theme.


  • Announcing [Your Product]: Be the First to Experience [The Benefits]
  • You’re Invited: Come See [Your Company’s] Great New Gallery
  • The All New [Product Name] – Be the First to Get All the Details

6. The ‘How To’ Subject Line

Why does the ‘How To’ subject line work? Because the value of your content is immediately apparent. The reader knows that opening your message will educate him or her on how to solve one of their problems.

When delivering a ‘How To’ subject line, focus on the benefits that the reader will enjoy – make it enticing by offering something of value.


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  • How To [Accomplish Something Great Using Your Product]

7. The Best and/or Worst Subject Line

We learned this tip from the Jungle Book as kids: “You’ve got to eliminate the negative and accentuate the positive.”  It’s a good way to add spice to your usual subject lines.


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8. The Pop-Culture Subject Line

Using popular culture is a great way to appeal to people’s need to feel included in the group and leverage something that’s obviously popular already. It can add a little interest to an otherwise boring topic.


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9. The 45 Character, 11.5 Word Subject Line

Subject lines that are too short will often fail because the benefit of reading isn’t made clear. On the other hand, adding too much detail has a negative impact. More people use smartphones and even smart watches to browse, and screen width is limited – long subject lines can be less effective.

What’s the perfect length? Opinions vary, but most studies agree that 40–50 characters or 9–14 words is optimal. We’re aware that some of our subject lines above bend that “rule” – our advice is to bear in mind the idea that relatively short subject lines are statistically most effective, but experiment and measure to discover what works best for your audience.


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  • 5 Simple Ways That [Your Product] Can [Deliver a Clear Benefit]


Making your message stand out in the inbox queue is a challenge. Deciding which mails to open and which to send to the trash is a snap judgement – it happens in a moment. It’s important that your subject line immediately offers something of value to any potential client. An effective subject line will vastly improve your open-rate.

Use the above nine formulas to create irresistible subject lines, tweaked to fit your message and audience perfectly. Remember to keep it at optimal length, and be specific. Clearly show what reading the rest of the message will give the reader.

Other useful resources for creating optimal subject lines can be found here:

Question: What are some subject line formulas that work well for you?