Email Subject Line Tester
Score your subject line before you send — improve open rates with data-driven feedback
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5 Email Subject Line Best Practices
Writing subject lines that get opened is both an art and a science. Here are five data-backed tips to consistently boost your open rates.
- Keep it between 30–50 characters. Most mobile email clients truncate subject lines at 35 characters. Desktop clients show around 60. Aim for the sweet spot where your full message displays on both.
- Use one power word. Words like "exclusive," "proven," and "essential" trigger curiosity. Don't overdo it—one strong power word is more effective than stacking three.
- Add a number or statistic. Subject lines containing a number see roughly 15% higher open rates. Specificity builds credibility (e.g., "5 ways" or "23% increase").
- Create urgency without being spammy. Phrases like "ending tonight" or "last chance" work. All-caps "ACT NOW!!!" ends up in spam. The line between urgency and spam is subtlety.
- A/B test everything. Even small changes in wording can swing open rates by 10–20%. Send two variants to a small segment, then roll out the winner to your full list.
Send Better Emails with GoHighLevel
GoHighLevel includes a full email marketing platform built for agencies and small businesses. You get a drag-and-drop email builder, automation workflows that trigger based on contact behavior, and built-in A/B testing so you can test subject lines at scale.
Their deliverability tools help you monitor reputation, warm up new domains, and keep your emails out of spam folders. Combined with SMS, CRM, funnels, and scheduling in one platform, it eliminates the need for five or six separate subscriptions.
Plans start at $97/mo with a 14-day free trial—no credit card required.
Frequently Asked Questions
A good subject line is 30–50 characters, includes a power word, creates curiosity or urgency, and avoids spam triggers. Subject lines with numbers get roughly 15% higher open rates. Personalization tokens like [Name] can further boost engagement when your list supports them.
30–50 characters is optimal. This ensures the full subject line displays on mobile email clients (which typically show around 35 characters) and desktop clients (which show around 60 characters). Going over 60 characters means most readers will see a truncated version.
Yes. GoHighLevel includes a full email marketing platform with a drag-and-drop email builder, automation workflows, A/B testing for subject lines and content, and deliverability monitoring tools. Plans start at $97/mo and include a 14-day free trial. Start your free trial here.