My Blog

The subject line is the very first impression your reader gets from your email. And in today’s world—where inboxes are crowded and attention spans are shorter than ever—it can also be the last impression if your subject line doesn’t spark curiosity.

To help you stand out and drive more opens, here are 8 subject line formulas you can swipe and adapt for your next campaign.

1. The Question Subject Line

A well-placed question instantly makes readers pause and reflect. Questions feel personal because they encourage people to think about their own habits or experiences.

For example:

• Do you check your emails first thing in the morning?
• Are you a zombie without your morning coffee too?

These work because they’re relatable and curiosity-driven. If a subscriber sees themselves in the question, they’ll be compelled to click and find out more.

2. The “How To” Subject Line

There’s a reason copywriters say you can’t go wrong with “How to.” It’s straightforward and tells readers exactly what value they’ll get.

Examples:

• How to get better marketing results through beautiful design
• How to gain 1,000 new email subscribers in a single day

The trick here? Focus on the benefit, not the process. People don’t care about learning another method—they care about the outcome (more sales, more subscribers, better results).

3. The Scarcity Subject Line

Few things move people to act faster than the fear of missing out. Scarcity taps into urgency by putting a limit on time or availability.

Examples:

• Only 2 days left to get 50% off shoes
• Hurry! Just 3 consultation spots left

But here’s the catch: it only works if the offer is relevant. If your audience doesn’t care about shoes, the discount won’t matter. Pair scarcity with something they genuinely want, and you’ll see results.

4. The Announcement Subject Line

Words like “Introducing” or “New” make people feel like they’re getting fresh, exclusive information. And data backs this up: subject lines with “Introducing” see a 9.45% lift in opens, while “New” gives a 3.26% boost.

Examples:

• Introducing a smarter way to send emails
• Update to our iPhone app
• See our new design gallery

This formula works because it promises something different and exciting.

ALSO READ: Reducing Email Bounce Rates: Tips for Better Deliverability

5. The Number Subject Line

Numbers give structure, set expectations, and make content feel digestible. In A/B tests, number-based subject lines consistently outperform text-only ones.

Example:

• 3 steps to measuring your email marketing success with Google Analytics
  (vs. How to measure your email marketing success with Google Analytics)

The numbered version got a 57% increase in opens.

Some other examples:

• 30 ways to grow your email list
• 10 product launch emails reviewed for conversions

Pro tip: Use smaller numbers when the process seems like work (“3 easy steps to lose holiday weight”) and larger numbers when showcasing value (“15 insider tricks to grow your subscribers”).

6. The Curiosity Gap Subject Line

Sites like Buzzfeed built entire empires on this tactic. The curiosity gap happens when you reveal just enough to spark interest—but leave out the full story.

Examples:

• This little-known copywriting trick will boost your CTR
• 9 out of 10 Australians are completely wrong about this fact
• Dave Richardson asks the simplest question ever—and stumps politicians

These lines work because readers can’t resist filling in the blank. The itch to know more practically forces them to open.

7. The Surprise Subject Line

Everyone loves the unexpected—whether it’s a clever joke, a witty pun, or just something out of the ordinary. Surprise creates delight, and delight sparks opens.

Examples:

• Warning: Unattended items in your cart may be eaten by gnomes
• What Elvis Presley can teach you about email marketing

Even something as simple as Obama’s campaign subject line—“Join me for dinner?”—worked because it came from an unexpected source: the President.

8. The Personalized Subject Line

A person’s own name is the sweetest sound to them—and yes, it works in email too.

Research shows that adding the recipient’s name in the subject line can increase open rates by 14.68%.

Examples:

• John, are you a zombie without your morning coffee too?
• Amy, 9 out of 10 people are wrong about this simple fact
• Paul, only 2 days left to grab 50% off boots

When paired with other formulas (like curiosity or scarcity), personalization makes the subject line feel even more relevant and urgent.

Final Thoughts

Your subject line is the gateway to your email—it decides whether your message gets read or ignored.

While it’s not always easy to come up with fresh ideas, these 8 formulas give you a strong starting point. Experiment, A/B test, and see which styles resonate most with your audience.