Free AI-powered Email Subject Line Generator
Tired of all the basic subject line generators that give you the same old cookie-cutter ideas? Create unique subject lines with the only free AI email subject line generator based on the Open AI technology
August 2024 update: We’ve updated the subject line generator to work with ChatGPT-4o
Our AI subject line generator can contextualize queries from Taylor Swift, self-publishing, Yeezy’s, and succulents — then spit out seductive email subject lines that would’ve taken a skilled copywriter hours to craft.
This isn’t some templated system that doesn’t understand your industry’s lingo.
We use the GPT-4o protocol developed by OpenAI (co-founded by Elon Musk) to scrape the internet and predict human-like word formulations to produce crazy good copy for the best subject lines.
If you’re still on the fence about using the tool (which is ludicrous — this is a free tool!) and want to know how to write high-converting subject lines, below, we’ve got you covered. We even share 15 subject line templates you can steal today.
Contents
Why are email subject lines important?
First impressions are everything.
In the dating world, how people present themselves determines whether you swipe left or right.
For email marketers, the subject line is the first thing a reader will see in their inbox.
How much does this matter?
According to OptinMonster: 47% of recipients decide to open an email based on the subject line, and 69% of email recipients report email spam based solely on the subject line.
Even if someone doesn’t open the email, your subject line still influences your audience’s perception of your brand.
Email agency Adestra analyzed over 3 billion emails, 300 keywords, and 4 industries. Here’s what they found:
“Whether or not your email gets opened, people see your subject line. What this means is that a subject line builds your brand in your customer’s inbox. Even if it doesn’t get opened, it creates a psychological association between your subject line and your brand. Over time, it creates a cognitive association between the language you use and the perception your customers have about you.”
So if it’s influencing open rates, avoiding spam, or building your brand, mastering your email subject lines is one of the most impactful things you can do as a business.
What types of email subject lines get opened?
To know which subject lines get the opened the most, you first need to understand the curiosity gap.
As renowned Conversion Copywriter Joanna Wiebe describes it:
“The curiosity gap, also known as the information gap, is the space between what we know and what we want or even need to know.”
Prospects want to fill the information gap. They’re itching to know.
Not knowing everything is compelling to people. Uncertainty garners attention, and it’s why the news has such high ratings.
Our job as marketers is to delay access to the curiosity gap to get users to take action. In this case, email subject lines.
Andrea Pearson, Author of Killer Subject Lines, got a 60% open rate using this subject line:
You wonder if Andrea is about to get religious in her email. If so, what has happened to cause her to share something she wouldn’t usually share with her readers?
We better read the email to find out. Bang! There’s the curiosity gap.
What types of email subject lines are prohibited by the CAN-SPAM Act?
Starting with what types of subject lines are prohibited will save you time and headaches down the line.
The CAN-SPAM Act is a law that sets rules for commercial emails, whether it’s one or many recipients.
The Act states that you cannot use deceptive subject lines. Meaning the subject line must accurately reflect the content of the message.
Not only is this a law, but it’s also best practice for building a positive relationship with your prospects.
Nobody likes click bate, and it’s a quick way to lose trust.
It’s also worth noting that you should avoid using question marks and exclamation points in the same subject line. For example:
“Want to reach more listeners? Check this guide now!”
This combination tends to have an increased chance of being flagged in spam before your reader has had a chance to see your message.
How to write attention-grabbing subject lines that get opened using psychological tactics
Humans are generally responsive to a handful of tried and true psychological tactics. Below are five prompts to integrate into your subject lines.
1. Start your subject lines with action verbs
In 2015, Microsoft released a study suggesting that human attention spans had dropped below 8 seconds. Down from 12 seconds in 2000 — making us more scattered than your average goldfish.
Tell readers what you want in your subject line by placing the most important words first.
Get, join, try—are action verbs. They take the guessing work out of what your prospect needs to do.
If you want more ideas, check out this action verbs resource list with hundreds of examples to include in your email subject lines.
2. Indicate if you need readers to respond
An extension of using action verbs is to ask readers how you want them to respond.
Make your request clear so users can quickly process what’s required.
Also, make sure you are not using a no-reply email address.
3. Use emojis
Emojis in email subject lines are rare, so they stand out in inboxes — capturing users’ eyes.
However, using emojis in copywriting is a polarising topic with varying degrees of success.
Be sure to A/B test your emails with 1 variant with an emoji another variant without one — to see how your readers respond.
Avoid overusing emojis. For instance, don’t put “Do you love dogs?”, then replace the word “dogs” with an emoji of a dog.
Your subject line still needs to stand on its own. Emojis are merely used to add stimulation to your message to grab attention.
4. Match your subject line tone with the theme of your brand
What’s the personality of your brand?
- Are you direct and to the point? Keep your subject lines straightforward.
- Radically transparent? Be vulnerable.
- Fun and upbeat? Add enthusiasm or emojis (see the previous point).
- Unapologetically curse in your copy? Drop a sh*t bomb in there.
Yes, your main objective is to get folks to open your emails. But you also want to build your brand. And a consistent voice and tone will ultimately lead to developing community and increased conversions.
5. Add personalization
Personalization is where you use a recipient’s name in a subject line. A study shows that 26% of emails with personalization have a higher chance of being opened, yet only 34% of marketers use personalization in subject lines.
The idea is that users are more inclined to engage with emails where their name is referenced. Especially, if it contains the word “video” as Syndacast has found that using the word “video” can lead to 19% boost in open rates.
A study conducted by Experian found that personalized emails have a 29% higher open rate.
However, marketers, especially large corporations, have overused this tactic, and users naturally become numb to these emails. Perhaps even seen as impersonal and even annoying.
Experiment with personalization and at least use it sparingly with your audience to preserve its magic.
For its Million Dollar Year program, Dow Janes, a financial education company for women, A/B tested a subject line with personalization to get its members to open the email and share their wins.
The 2nd subject line generated a 42% increase in opens, leveraging personalization and curiosity. Imagine if you receive an email like with this subject line — you’d most likely open it to find out what you did to deserve the congratulations.
6. Why “weird words” in your email subject lines can help you snag eyeballs
Unusual words can turn average statements into interesting ones.
What’s more compelling?
The second statement uses a more imaginative verb that creates an entirely different vibe.
Let’s look at another example:
Another trick is to replace common words like “simple” or “easy” with something more specific or descriptive.
Which one grabs your attention more?
Find unusual ways to say ordinary things, and you’ll grab more attention in your email subject lines.
Just be sure that your readers are likely to understand your kooky wording. See what we did there?
7. Add urgency
A sense of urgency in your subject lines compels recipients to act quickly, reducing the likelihood that your email campaigns will be ignored or forgotten. A study by Invesp found that subject lines with urgency and exclusivity have 22% higher open rates.
By creating a sense of immediacy, you tap into the reader’s fear of missing out (FOMO), which can drive higher open rates and prompt quicker engagement. Whether it’s a limited-time offer or a fast-approaching deadline, an urgent subject line can effectively cut through the clutter and encourage immediate action.
Examples include: “Just [X] left”, “Last chance to [action]”, and “Only [X] days/hours left to [action]”.
8. Use metaphors
Writing funny subject lines using metaphors is a great way to grab attention and add a playful touch to your emails. Metaphors allow you to creatively convey your message while sparking the reader’s imagination. For example, a subject line like “Our new feature is a total game-changer — like turning a pumpkin into a sports car” or “This deal is sweeter than grandma’s apple pie” uses humor and vivid imagery to create a memorable impression, encouraging recipients to click and see what’s inside.
9. Tap into curiosity
By intentionally leaving out key details, you create an intriguing sense of mystery that compels the reader to find out more. For example, a subject line like “You won’t believe what we just launched…” or “This surprise is just for you…” invites curiosity without revealing the full message. This approach plays on the human desire to fill in gaps, making it hard to resist clicking to discover the full story.
10. Use your brand’s voice
Your brand’s voice will help you maintain consistency and build a recognizable identity across inboxes. It helps reinforce your company’s personality and tone, making your emails feel more familiar and relatable to your audience.
Whether your brand is witty, formal, or conversational, keeping that tone in subject lines strengthens the connection with your audience. For example, a playful brand might use, “We’ve got something cool just for you!” while a more professional brand might opt for, “Here’s how we can help improve your workflow.”
You can use the tone dropdown in our tool to generate subject line ideas that resonate with your brand’s voice and reflect your target audience.
How long should an email subject line be?
Desktop email clients see about 60 characters, while mobile clients see 20-25 characters.
According to 99firms, 85% of users use smartphones to access email. So aim to keep your subject lines 6-8 words or under 50 characters to account for smaller screens.
As an aside, Gmail and Apple Mail make up 62% of the mobile email client market share. When testing the ideal length, see what your subject lines look like in these apps.
What not to include in your email subject line
The odd bad copywriting tactic can work for some. But more likely, these practices will deter your audience.
Below are six things to avoid putting in your email subject lines.
- Filler words – words like “Hi,” “Hello,” and “Nice to meet you” don’t describe what’s in your email — so users are likely to disregard it. Based on the previous point about subject line character length — save your word budget for more impactful phrases.
- Shocking statements – it’s tempting to be dramatic and make controversial click-baity proclamations that get your readers’ hearts pumping. Sure, you’ll get more people opening your messages, but they’ll be disappointed if you don’t deliver on your claims — creating brand detractors.
- Charity-related words – MailChimp studied 24 billion delivered emails and found that requests for donations in the subject line are largely ignored. Avoid using words like “donate,” “fundraiser,” “raffle.” If you’re a charity organization, using the words like “help” or “helping” has a slightly better impact on open rates.
- Spam-related keywords – you want to avoid any offensive or explicit words that may get your email into the spam folder of email clients.
- RE: and FWD: tags – it is tempting to use sleazy tactics like emulating email replies by prepending your subject lines with RE: and other words, as they often work. However, you will quickly burn the trust of your audience and make them mad, which leads to higher unsubscribes and spam reports.
- Excessive punctuation marks – an occasional exclamation or question mark is great, but overdoing it (?#?!?) can quickly get your email in the spam boxes, so you want to go easy on them.
- The word “request” – Agari found that “request” is the most common used term in BEC emails (Business Email Compromise — a type of phishing email that targets employees or companies who send wire transfers to partners or vendors).
- The word “you” – A study by OptinMonster shows that using the word “you” might lead to a decreased open rate of 5%.
Why should I use a subject line generator?
Advertising legend David Ogilvy famously rewrote an automobile headline 104 times to come up with this:
“At 60 miles an hour, the only thing you hear in the new Rolls Royce is the ticking of the dashboard clock …”
Jimmy Donaldson, the mastermind behind the fastest growing YouTube channel, MrBeast, will not publish a video until he’s happy with his title and thumbnail.
The highest-performing marketers spend an inordinate amount of time crafting copy that gets a response.
And if we’re honest with ourselves, email subject lines are usually an afterthought. Even despite investing time into the email content, product offering, sales funnel, and landing pages.
The best marketers spend hours writing and testing subject lines. But for everyone else, this practice isn’t feasible.
A good email subject line generator can save you hours in your marketing budget while boosting your results.
Our subject line generator uses AI and machine learning to leverage all of the human psychology tactics covered in this guide.
Simply type in your query, and voila, you have fresh high-converting copy ideas ready to insert in your subject line.
Can I generate subject lines for free?
There are free email subject line generators on the market. However, most of them rely on rotating templated phrases, which is restrictive. More specifically, they’re trying to fit your query into pre-written templates.
Encharge’s subject line generator is free and uses GPT-4o protocol, a comprehensive database of predictive AI, to create infinite combinations that tap into human psychology.
Should I use a cold email subject line generator?
The subject line for marketing emails is equally important for cold emails.
So you absolutely can use our AI subject line generator to create engaging email subject lines for your cold emails to increase your opens and replies.
However, note that marketing automation tools like Encharge do not allow the sending of cold emails.
What if you want to write your own email subject lines?
If you prefer to write your own email subject lines, we’ve created s list of proven templates to help.
A few things to remember when crafting your subject lines:
- Get your ideas across quickly and effectively.
- Grab readers attention by finding the curiosity gap.
- Test, optimize, and tweak your subject lines with a tool like Encharge until you get the perfect subject line!
Let’s get into the examples.
15 email subject line templates you can use today
1. Here’s your [promise]
For example:
No-nonsense subject lines are powerful, especially when dealing with orders or new signups.
Tips
- Keep your message simple and direct
- Describe precisely what your recipient is receiving
- A/B test more descriptive variations of the deliverable. For example: “Here’s your free property market report”
This method doesn’t play much on the information gap, but it’s effective nevertheless.
2. [Word]
For example:
Subject lines using a single word are compelling as your eye is instantly drawn to them, and they stand out when every other subject line in your inbox is lengthy.
Tips
- Don’t overuse the single-word subject line, as your readers will start to catch on, and it won’t feel as unique.
- “Sorry” works well, especially if you’ve made a mistake in a previous email. It’s often better to go with a one-worder when apologizing to your readers.
It’s difficult to describe something in one word, so this template naturally plats on the curiosity gap. Other examples include “Stop,” “Crap,” “Tomorrow.”
3. How to [achieve something specific]
Example:
People love self-help content, and the classic how-to subject line promises a solution to a problem.
Tips
- This template works best when making the problem as specific as possible.
- Deliver the solution in your email message.
This formula’s effectiveness depends on how much your audience wants a solution to the problem you’re presenting.
4. [Timeframe] only
Example:
The fear of missing out creates urgency and is a massive motivator. It’s human nature not to miss out on opportunities, especially if that means saving money.
Tips
- When employing scarcity, be truthful with your deadlines. If you say the sale ends tomorrow, then it should end tomorrow. Following through on your commitments will only increase the motivation for your customers to pull the trigger next time.
- Be mindful not to use this technique too many times in a row. Otherwise, it starts to look like reminders that can be off-putting to your prospects.
A bit of ambiguity goes a long way with the scarcity technique as it plays on your audience’s curiosity, enticing them to open your email.
5. Why [x] trumps [y]
Example:
We all have to make difficult choices. Should you rent or buy a property? Is powerlifting better than high-intensity interval training?
This subject line template promises to help the user make a decision.
Tips
- This method works best when you aim to bust a myth in your comparison. For example, option A may appear to be the obvious answer, but you make a case for option B.
- Find the hottest debates in your industry, then drop this subject line to provide a definitive answer. Not only will you get more opens, but you’ll also build your brand authority.
As this template plays on busting myths or unexpected comparisons, it again taps into the readers’ knowledge gap — increasing curiosity.
6. [Ask a burning question]
Example:
It’s no secret that questions work well in copywriting. But do you know what’s even better? A biting question that keeps your readers up at night.
Tips
- Choose a question that’s top-of-mind for your prospects.
- Find emerging industry trends that create uncertainty for your audience, and help them navigate the change.
- Always deliver the answer to the question; otherwise, it’s just clickbait.
Naturally, this template plays on your readers’ information gap—so it’s a good move to have in your bag.
7. [n] Ways to [achieve something specific]
Example:
Listicles, while overdone (thanks, BuzzFeed!), are still effective. Lists provide clarity and order in our minds, and they always will.
Tips
- Like the how-to template, try to make your subject line as specific as possible unless your brand is more generic.
- For added interest, include adjectives directly after your number. For example: “10 Sneaky ways”, 10 Legitimate ways”, 10 Creative ways”.
Even if your audience is familiar with the topics in your subject line, they may still be intrigued to see if there’s something on your list that they haven’t thought of before.
8. Why [surprising fact]
Example:
People want to know “why” as much as they want to know “how.” For instance, children always want to know why things are the way they are. Why do people get sick? Why do I have to go to school?
Adults are just as curious. It just depends on how it’s framed.
Tips
- “Why” statements are bland if the answer is obvious. Include compelling or borderline controversial facts to pique the interest of your audience.
- State what your reader thinks is the status quo and challenge it. For example, “Why working from home is killing your productivity.”
- Back up your statement with credible facts and solutions.
Challenging what is considered best practice creates tension for your audience, persuading them to open your email.
9. The [famous person] of [category]
Example:
We all aspire to be great — and look at uber-successful people to draw inspiration in our fields. This subject line leverages the name of someone famous in a category that wouldn’t be associated with this person or brand.
Tips
- Pick someone universally known with a high approval rating, e.g., Michael Jordan, Apple, Oprah, etc.
- Choose a person who’s completely unrelated to your topic to create an exciting contrast.
Having your readers imagine how said famous person would approach your industry is intriguing and clickable.
10. The secret to [accomplishing the desired outcome]
Example:
Everyone wants, no, needs to know the secret to success. So spill the beans and give your prospects what they want.
Tips
- Add interesting adjectives to spice up your copy. For example: “The surprisingly simple secret to being an amazing mother.”
- In your promise, try to share advice that’s either a) something you’ve personally tested and seen results, b) a little unconventional or c) inside knowledge that you’ve acquired.
Use this subject line formula sparingly as it quickly becomes icky and off-putting.
11. Do you make these [topic] mistakes?
Example:
Nobody wants to make mistakes and will do what they can to avoid them. Depending on how interested your reader is in your topic, this subject line will be sure to grab their attention.
Tips
- You can test question vs. statement for this template, e.g., “Do you make these hiring mistakes? vs. “Don’t make these hiring mistakes.”
- Play around with the order. For instance: “Do you make these mistakes when recruiting talent?”
As mistakes are evident in any niche, this subject line template is incredibly versatile.
12. What type of [interest] are you?
Example:
People love classifying and comparing themselves to others. It gives them a moment of clarity, and it’s why personality tests and horoscopes are so popular.
Tip: This subject line works beautifully if paired with a quiz where users can more accurately categorize themselves. But even if you don’t run quizzes, you can provide different personas to match the topic.
The desire to learn more about ourselves is strong, so it’s worth finding creative ways to try this subject line.
13. How [person/company] got [results] in [timeframe]
Example:
This email subject line works wonderfully when showcasing customer case studies to your subscribers.
Tip: Split test different formats of the timeframe, e.g., 30 days vs. 4 weeks vs. 1 month, to see which one resonates the most.
Case studies are magical marketing materials for middle to bottom of the funnel messaging. We all want the blueprint of how others get the results we desire. This subject line presents an enticing knowledge gap — pulling readers to open your email.
14. The future of [topic]
Example:
Bold predictions pique interest and position your brand as a forward-thinking industry leader.
Tips
- A/B test question vs. statement, e.g., What’s the future of Instagram marketing? Vs. The future of Instagram marketing.
- Another prediction subject line template is: “How
[topic]will change in[year]. Keep this headline in your back pocket for when you near the end of a calendar year.
This subject line is particularly relevant as technology has fast-tracked the development of just about every industry, and users want to know what to expect.
15. Read this before [action]
Example:
This subject line is the equivalent of a parent, friend, or boss giving you advice about something important you’re about to do.
Tips
- Ensure your action is something your subscriber desperately wants to do well (that’s related to your niche, of course).
- Another headline template is: “What you need to know about [action].”
- Think: will the reader miss out by not following the advice in the email?
What’s brilliant about this headline is that you can tie it directly into your email automation and predict exactly when your prospects will need this information, increasing your conversion rates.
16. Why/how [percentage]+ [unexpected thing]
Example:
This subject line taps into readers’ natural curiosity, enticing them to learn more about the topic, especially if it’s something relevant to their interests.
Tips
- Ensure the topic is relevant to your target audience. For example, if you write about social media, a relevant topic could be “How Facebook lost 20% of its audience in 1 day.”
- This subject line is most powerful when timed with a recent event or a trendy topic.
- Avoid false facts.
You can quickly get dozens of subject line ideas by following news outlets in your industry.
17. [Quote]
Example:
Quotes are a powerful way to tap into the mindset of your readers, either by quoting something that they could potentially say (like you are a mind reader) or by endorsing a popular figure in your industry.
Tips
- Keep notes of common sayings/thoughts of your audience. You can later use them in your subject lines to instantly connect with your readers on a personal level. They will think, “Hey, this person really understands me,” and feel attracted to click on the subject line.
- Use controversial quotes to attract attention.
- Use common/stereotypical thoughts as quotes and debunk them as myths. For example: “Why “time is money” is wrong”.
If you need subject line suggestions, you can ask your email readers to respond to your messages about issues pressing to them. You can then include their responds as quotes.
Further Reading
- 6 Killer Tips to Craft Compelling and Clickable Email Subject Lines
- 8 SaaS Copywriting Techniques to Boost Your Conversion Rates
- Damaging Words to Delete from Your Emails in 2022
- Is Marketing Automation Going to Replace Humans in 2022?
- 5 Ways AI Will Impact the Future of Sales and Marketing Automation
- Machine Learning and Marketing Automation – Will ML Transform Your Business?
- Top 7 Marketing Automation Trends in 2022 According to 103 Experts
- How to Use AI In Your Lead Generation Efforts
Go beyond the email subject line generator – generate impactful emails
Encharge is the only marketing automation platform with built-in AI-powered copy generating capabilities. Our Magic Writer feature can help you come up with dozens of subject line ideas in a click. But that’s not all.
The Magic Writer can generate whole emails for you, write unique outlines for your emails, and even rewrite existing subject lines. Want to take it out for a spin? Sign up for a 14-day free trial today.
