Ever found yourself staring at a blank field, struggling to craft the perfect email subject line—only to settle on something forgettable? If you’ve ever wondered why your emails go unopened, you’re not alone. Studies consistently show that over 47% of people decide whether to open an email based solely on the subject line. That makes learning how to write a good subject line crucial for anyone who hits ‘send’—whether for business, a newsletter, or personal outreach.
So, what makes a good email subject line? At its core, a great subject line is clear, relevant, and sparks enough curiosity or value to make the reader want more. In the next few minutes, you’ll discover actionable tips and proven strategies for writing subject lines that actually get your emails opened. Let’s dive in.
What Makes a Good Email Subject Line?
The secret sauce to a great subject line isn’t complicated—but it does require focus. Good subject lines are:
- Clear and specific – The reader should instantly understand what your email is about.
- Personalized – Using the recipient’s name or tailored content increases open rates.
- Relevant and timely – Addressing something the reader cares about, right when it matters most.
- Concise – Most inboxes will cut off subject lines after about 50 characters.
- Action-oriented or curiosity-provoking – Give them a reason to click, whether it’s answering a question, offering a benefit, or teasing something valuable.
For example, “Here’s your April Newsletter” is generic and skippable. By contrast, a subject line like “Your April Checklist: 5 Ways to Save Time” is specific, relevant, and promises a clear benefit—making it more likely to be opened.
Start with Clarity: Be Direct and Honest
Wondering how to write a good email subject line every time? Start by being as straightforward as possible. Avoid vague phrases or misleading clickbait. If your email contains a webinar invite, say so: “Join Our Webinar: Grow Your Audience in This Year.” This honesty builds trust and sets the right expectation.
Why it works: People are busy and skeptical of digital noise. Clear subject lines respect their time and make the email feel less like spam.
When to use: Every time you need your message to come across as credible—especially with business updates, newsletters, or transactional emails.
Personalize for Relevance
Personalization isn’t just about using someone’s name (though that helps). It means referencing something unique to the recipient, like recent actions or interests.
For example: “Welcome back, Jamie – see what’s new this week!”
Why it works: Emails that feel personally relevant are more likely to be opened. According to recent data, emails with personalized subject lines see a 26% higher open rate.
How to do it: Use your email tool’s merge tags for first names, past purchases, or location. In platforms like AWeber, this is easily automated, letting you scale relevant, customized messages for every subscriber.
Use Numbers, Lists, or Formulas
Numbers are eye-catching and promise value right up front. Try list-style or formula-based subject lines, such as:
- “3 Quick Tips to Improve Your Open Rates”
- “Launch Your 1st Email Campaign”
- “Save 20% on Your Next Event – Ends Friday”
Numbers provide a concrete preview of what’s inside, making the message feel scannable and practical.
When to apply: If your content delivers a step-by-step process, list, or offer, include the most compelling number right in the subject.
Inspire Curiosity, but Don’t Mislead
Curiosity is a powerful motivator—but be careful not to overdo it or make false promises. Instead of vague teasers like “Don’t miss this!” try a curiosity-based but informative approach: “One Strategy Most Marketers Miss in Email.”
This hints at a benefit, sparking the reader’s desire to learn more without resorting to deception.
Example: “What 98% of Senders Forget When Hitting ‘Send’”
This type of subject line works best with educational content, tips, or case studies—especially when you can surprise the audience with something new.
Keep It Short and Mobile-Friendly
More than 60% of emails are opened on mobile. Aim for 6–10 words or about 50 characters. Test how your subject line displays on your own devices, especially if your audience is on the go.
Shorter subject lines cut through the clutter and are less likely to be truncated. Try to frontload meaningful words (put the most important details first):
“Free Template: 2026 Content Calendar” reads better than “Here’s a free template you’ll love for 2026.”
Bonus Strategies: A/B Testing and Emojis
A/B Test Your Subject Lines
The truth is, there isn’t a single approach that works every time. A/B testing your subject lines—sending two variations to a small percentage of your list—helps you learn what your unique audience responds to.
For step-by-step guidance on this, check out AWeber’s detailed guide on how to A/B test your email subject lines.
Use Emojis Thoughtfully
Emojis can make your subject lines stand out, but only use them if they fit your brand and audience. One well-placed emoji can increase open rates, but overuse can make your message appear spammy.
Example: “🎉 New Features Just for You!”
Always preview your emails on multiple devices to check how emojis display.
Real-World Examples of Good and Bad Subject Lines
| Good Subject Line | Why It’s Effective |
|---|---|
| “Unlock Your Free SEO Checklist” | Offers value, clear benefit |
| “Reminder: Webinar Starts in 1 Hour” | Specific & time-sensitive |
| “[Guide] Fix Your Open Rates Today” | Problem-solving & targeted |
| “Jamie, See Your August Updates” | Personalized, timely |
Compare those with less effective examples like “Newsletter #15”, “Check this out!”, or “Hey!”—which lack relevancy, clarity, or a compelling reason to open.
3 Quick Formulas for Better Subject Lines
- The Benefit Formula: “Get [Result] in [Timeframe]” (“Get More Leads in 7 Days”)
- The Curiosity Formula: “What You Don’t Know About [Topic]” (“What You Don’t Know About List Building”)
- The How-To Formula: “How to [Achieve Result] Without [Pain]” (“How to Write Great Subject Lines Without Guesswork”)
Try these templates and see which resonates most by testing on your next campaign.
Helpful Tools for Crafting Better Subject Lines
Many modern email marketing platforms offer subject line preview tools that show what your line will look like across devices. Use these tools to check length, clarity, and even preview how personalization will appear for recipients.
For more subject line inspiration, browse AWeber’s curated list of winning email subject line examples.
Use a Subject Line Generator for Fresh Ideas
Even the best email marketers hit a creative wall now and then. That’s where subject line generators come in handy—they’re great for brainstorming new angles and speeding up your writing process. If you ever find yourself stuck, try AWeber’s Subject Line Assistant. Just enter a few details about your email, and it instantly gives you subject line ideas tailored to your content. It’s a quick way to spark inspiration—and even test out options you might not have thought of on your own.
Keep Improving: Learn What Works for Your Audience
Mastering how to write a good email subject line is an ongoing process. Review your open rates and pay attention to patterns—are personalized subject lines performing best, or are short, benefit-driven lines winning out? Use that information, along with regular A/B tests, to evolve your approach.
To recap: always lead with clarity, make subject lines relevant and personal, keep them brief for mobile readers, and don’t be afraid to test and iterate. With these tools, you’ll get more eyes—and more engagement—on your next email!
