12 Email Subject Line Formulas That Will Help Boost Your Open Rate

I have a set of email subject line formulas I constantly use, both for my clients and when promoting my business.

They work.

They get subscribers to click.

And help me boost traffic and engagement.

And today, I’m going to share some of the best-performing ones with you.

So, if you’re struggling with writing subject lines that will compel subscribers to read your emails, this post is definitely for you.

Intrigued? Let’s get started.

Bonus: Download the email subject line cheat sheet that will show you how to increase the open rates of your emails.

Why A Subject Line Can Break Your Email

Take a look at some of these stats:

• 69% of recipients report messages as spam based solely on the subject line (source).
• And 47% open emails based entirely on the subject line (source).

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Crazy, huh?

But wait, there’s more:

As it turns out, email subject lines can have such an impact on recipients, that sometimes it pays off more not to have a subject line at all!

According to the guys at Sidekick, emails that contained no subject line get opened 8% more often than those with a subject line (source).

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But of course, not writing a subject line isn’t really an option. At least not for every email.

So why all the fuss about subject lines?

As a copywriter, Sheryl Lindsell-Roberts explains (note, the emphasis in bold is mine):

“The subject line is the most important piece of information in an e-mail message. It’s the first and only hint as to what your message is about—unlike a letter where the body is in full view. There are people who get hundreds of e-mail messages a day, and they can’t possibly read them all. So, if your subject line doesn’t seduce your readers, they may never open your message.”

Simple, isn’t it?

And yet… writing them is so intimidating at the same time.

So let’s take a look at some email subject line formulas that will help you compel more subscribers to open your emails.

12 Email Subject Line Formulas You Can Use to Promote Your Next Post

Formula #1 – Reason Why

Formula: [Number] Reasons Why [Something You Should Do/Try/Use/etc.]

Example: 5 Reasons Why You Should Spend More Time Writing Your Email Subject Lines

As its name suggests, this formula focuses on outlining the reasoning behind asking your audience to do something.

It works particularly well for emails that promote anything that lists features, benefits, or steps a person needs to take to achieve certain benefit.

Formula #2 – How-to

Formula: How to [Achieve Benefit or Result]

Example: How to Boost Your Email Open Rates

In his amazing book, “The Copywriter’s Handbook,” one of my copywriting heroes, Bob Bly, writes:

“Many advertising writers claim that if you begin with “how to,” you can’t write a bad headline. They may be right.” (see page 23)

How to subject lines work so incredibly well because they offer a promise of a solution or advice. Simply.

PRO TIP: If you want to boost this formula’s effectiveness, even more, add the phrase “this is” at the start of the subject line. For example – This is how to boost your email open rates. It will make the headline sound more firm, and even more reassuring about the solution it promises.

Formula #3 – Question

Formula: [Question regarding the pain point or benefit]

Example: Are you struggling to write compelling subject lines?

You know: questions have an incredible power to attract our attention. It doesn’t matter what you do, and how focused you are on the task. The moment your mind realizes that someone’s asking you a question, it’ll switch attention to it.

And it’s no different with email subject lines. Question-based subject lines compel a reader to find out the answer.

But here’s the trick – questions you ask in the subject line should always focus on your subscribers’ curiosity, self-interest, and needs. Only this way, you’re able to capture their attention and convince them to read the email.

Formula #4 – Benefit

Formula: [Benefit of overcoming the pain point, problem or challenge]

Example: Increase email sales.

I’m sure you’ve heard this old sales adage already – benefits sell.

And it applies to subject lines too. Openly stating the benefit of reading your email can help you connect with the email list and significantly increase your open rates.

Formula #5 – Social Proof

Formula: [Social Proof Proving – Ideally with Numbers- That a Particular Benefit Works]

Example: Check out email formulas that helped 65% of marketers boost their open rates.

Social proof is an incredibly powerful factor in every decision we make.

I wrote at length about the mechanics of social proof in marketing in this article on AdEspresso last year, and I strongly recommend you read it before using this formula.

But to give you a quick rundown (quoted from my AdEspresso post):

Social proof works because whenever we’re unable to make a decision, we look at what other people do, assuming that their actions are correct for the given situation. And we simply imitate their behavior.

And you can use that trait of behavior to convince your subscribers to open and read the email.

Great, huh?

Formula #6 – Targeted Call Out

Formula: [Your Audience] + [Question or Benefit Formula]

Example: SME Owners: Struggling With Low Email Open Rates?

Sometimes the simplest way to engage the audience is by convincing them that your email is relevant to them. And that’s what this formula helps you achieve.

It expands on two other formulas – question and benefit – by defining the audience of your email.

Formula #7 – Discover

Formula: [Discover] + [Benefit or How to Formula]

Example: Discover how to boost open rates with these 17 subject line formulas

This formula captivates a person’s attention by promising the discovery of a quick solution to their problem.

You can create it by adding the verb “discover” at the start of a Benefit or How-to formulas.

Formula #8 – Numbered List

Formula: [Number]+[Tips/Ways/Strategies/etc/] to [Achieve Desired Result]

Example: 20 Ways to Increase Email Open Rate

Dean Evans from Good Content Co. sums up the benefits of using list based subject lines wonderfully with these words:

“The list post headline is Mr Reliable; a safe bet; the go-to content format when you can’t think of anything better to write.”

And there’s really nothing else to add. List headlines work. Full stop.

Formula #9 – Curiosity Gap

Formula (ver 1): What You Don’t Know About [Pain Point or Challenge]

Example: What you don’t know about writing emails that sell.

Formula (ver 2): What [Known Person/Company Relevant to Your Audience] Can Teach You About [Pain Problem/Benefit]

Example: What Apple Can Teach you About Email Marketing

*Back in 1757, an Irish statesman, Edmund Burke, said (note, the emphasis in bold is mine):

“Curiosity is the most superficial of all affections; it changes its object perpetually; it has an appetite which is very sharp but very easily satisfied; and it has always an appearance of giddiness, restlessness and anxiety.”

In other words, once something arouses our curiosity, we won’t stop until we satisfy that craving for information.

And you can use it to compel subscribers to open your emails.

But remember – your subscribers don’t like to be cheated. When using curiosity gap, make sure that your email delivers on the promise you’ve made in the subject line.

Formula #10 – Announcement

Formula: New [Post/Update/Event/etc/]: [Topic]

Example: New Post: 12 Email Subject Lines That Will Boost Your Open Rate

Sometimes, it pays off to be direct – state the proposition clearly, without any wordplays, copywriting tricks, or puns.

This formula comes particularly handy if you simply want to announce something to your list – a new post, website update or an upcoming event.

Formula #11 – Urgency

Formula: [Last Chance to] [Act to Avail of Something]

Example: Last chance to save on your conference tickets.

The goal of using urgency is to make your subscribers think differently about opening the email. Instead of procrastinating, you want to motivate them to act now.

But there’s another benefit of using urgency – it helps prevent subscribers from over-analyzing the value of your email, and acting on it without thinking.

Because you see, when presented with something urgent, we stop thinking and begin to act on impulse.

Formula #12 – Warning

Formula (ver 1): Avoid [Common Mistakes or Negative Outcomes]

Example: Avoid These Common Email Marketing Mistakes

Formula (ver 2): Don’t [Do/Make] [Activity to Eliminate Challenge] Until You Read This

Example: Don’t Send Any More Emails Until You Read This

This is an another formula that attracts attention by targeting both your subscribers’ curiosity and anxiety.

By playing on the negative, you can entice someone to click the email. But just like with the curiosity gap formula – always make sure that your email delivers on the warning.

And there you have it…

Twelve email subject line formulas that will help you boost open rates, and convince more subscribers to read your emails.