Increase your open rates with subject line formulas

Looking for a way to increase your open rates for your campaigns? Look no further. We’ll dive into why your subject lines shouldn’t be the last thing you pay attention to, as well as run through some tried and tested subject line formulas that you can try to help you get going. Just like email templates are a useful tool to use as a foundation for your campaigns, subject line formulas can equip you with the knowledge you need to intrigue and engage your audience. Your subject lines are also incredibly important if you are looking to increase your open rates.

There’s nothing worse than taking time crafting your email campaign, sending it out and then seeing really bad open rates. What went wrong? It could be that your subject line wasn’t appealing enough to get your reader to read your campaign.

The “How To” Formula

“How to” subject lines are extremely effective as they tell your subscriber exactly what is in the body copy of your email, basically what they can expect from your email. People find lots of value in how-to content as it’s educational and answers a need they may have. The key when utilising this subject line formula is to make sure you clearly communicate what the benefit is to the subscriber. Make sure you describe the value proposition as clearly as possible.

“How to” Formula’s:

  • (Attention-grabbing thing): How to get/avoid (attention-grabbing thing)
  • How to: (add something useful here)
  • How to (add something useful here) without (something bad about it)
  • How (use recognisable business or person) does (XXX)


The straightforward email subject line is literally what it sounds like. It’s a basic subject line explaining exactly what type of mail you are sending. It’s very tempting to want to come across as witty or stand out by trying to be clever, sometimes when doing this however clarity is sacrificed for cleverness. A straightforward subject line gives you a great opportunity to just say it like it is which could go a long way to create consistency and provide value and trust. Sending straightforward subject lines over time creates consistency and trains your subscribers to expect certain communication from you.

Straightforward Formula:

  • (Type of email) | (Month, Year) + mini subject overview
  • (Type of email), Month Year


  • Don’t add your company name in this kind of subject line, the subscriber will already see this in your From name that you’ve set. This saves you a few characters.
  • Use “Daily” or “Weekly” in this kind of subject line to boost your open rates
  • If your newsletter has a name, use that but otherwise, you could try saying “Notice”, “News”, “Newsflash”

Ask a question

Asking a question is a great subject line formula to get people thinking and hopefully you will answer the question in your campaign. Connecting with your audience with a question in your subject line allows them to think about how the question relates to their life. This helps you connect with your audience.

Question-based subject lines also show a level of care from your side, which means your audience is more likely to feel emotionally attached to your brand. Research shows that 45% of people feel more emotionally connected to a brand that “gets them”.

Questions are great drivers as they also create curiosity.


  • Ask questions you know your audience is asking too

Scarcity and urgency formula

Fear of missing out or FOMO is definitely something that can help you increase your open rates through your subject line. Creating a limited time offer or telling subscribers only X amount of a certain product is still left is a great way to get them to act immediately.

Scarcity and urgency Formula:

  • (Something incredible) don’t miss out ends (today, number of hours)
  • (Last chance) to get (something incredible)
  • Never to be repeated: (Something incredible)


  • Don’t use this kind of subject line if you intend on extending your sale or if you have more products than you are saying you do. Be honest.
  • Losing trust with your subscribers can lead to drastic revenue loss.

Announcement formula

Announce something new or exciting that you’ve launched in your subject line. Have a highly sought after product you’ve just started selling? Tell people about it. Launching a new functionality or service? Announce what’s new in your subject line and get people excited and interested to find out more.

Announcement Formula:

  • New (Name of exciting thing)
  • Introducing (Name of exciting thing): (short benefit to subscriber)
  • New! (benefit of new thing without its name)

Number formula

A lot of people shy away from using numbers in their subject lines but research has actually shown that using numbers can significantly increase your open rates. Using stats in your subject line can help you boost your credibility too.

Number formulas

  • (Number) ways how (product) (answer a problem)
  • (Number)% of our clients (do XYZ)
  • People save (Number)% on (thing they save with you) by using (product/service/platform)

Listicle formula

A listicle is a numbered list that gives you information about a certain subject. Listicles have gained widespread popularity with content producers like Buzzfeed gaining great fame by using this content format. The reason why these content sources are so popular is because they are easy to digest and scroll through. A great subject line idea is to use a listicle heading as your subject line.

Listicle formulas:

  • 15 ways in which (your product/service) helps (benefit)
  • 10 great ways to use (product name)
  • 7 things you don’t know about (your business)

The Empty Suitcase formula

Ever heard of the empty suitcase? The empty suitcase is where you use this, instead of using a noun.

Empty suitcase formulas:

  • [FNAME], this is for you
  • You need this in your life
  • This is how you do (good thing/bad thing)
  • I (past tense action) and it changed (something epic)

General subject line tips:

  • Keep it simple
  • Keep to 50 characters or less
  • Write multiple options and then choose the best one
  • Use call to actions in your subject line
  • Keep your brand’s tone in mind
  • Add a preheader to your subject line, but remember to ensure the two can stand alone on their own
  • Speak directly to your audience
  • Spend time thinking about and creating a compelling subject line

Which of these subject lines are your favourite? Have you tested any of these in your campaigns? Let us know in the comment section below.


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