How is the score calculated?

The score considers length (30-50 chars ideal), word count, personalization, power words, spam triggers, and formatting. Each dimension is scored independently and combined into a weighted overall score. Higher scores indicate better predicted open rates.

What are spam triggers?

Words and phrases that email providers may flag as spam: "FREE", "Act Now", "Limited Time", ALL CAPS, excessive exclamation marks, and deceptive formatting. Our analyzer detects these and suggests alternatives.

Is my email data sent anywhere?

No. All analysis runs entirely in your browser. Nothing is uploaded or stored.

What is the ideal subject line length?

30-50 characters for desktop email clients. On mobile (where 60%+ of emails are opened), subject lines truncate after roughly 35-45 characters. Put the most compelling information in the first 30 characters.

What are power words and why do they matter?

Power words are terms proven through A/B testing to increase open rates: "proven", "exclusive", "essential", "secret", "guaranteed", "ultimate", "surprising". They trigger curiosity, urgency, or desire that compels the recipient to open.

Should I use emojis in subject lines?

Emojis can increase open rates by 10-15% in some industries but can also appear unprofessional in B2B contexts. Test with your specific audience. Avoid using multiple emojis or using them as a substitute for compelling copy.

Does personalization really improve open rates?

Yes. Studies consistently show that subject lines including the recipient's name or other personal details see 20-30% higher open rates. The analyzer checks for personalization patterns and suggests where to add them.

How accurate is the score at predicting open rates?

The score is a heuristic based on established email marketing best practices and research. It is a useful guide for optimization but actual open rates depend on your sender reputation, audience, send time, and many other factors beyond the subject line alone.

Email Subject Line Analyzer

Score your email subject lines for open rate optimization.

How it works

1
Paste your text

Paste or type the text you want to transform, analyze, or generate.
2
Apply the tool action

Run the selected conversion, generation, or formatting option.
3
Copy the output

Copy the processed text and use it in your document, app, or workflow.

Common use cases

Marketing email

5 Proven Ways to Boost Your Productivity
Spam-like subject

FREE!!! Act Now Limited Time Offer

About This Tool

Paste an email subject line and get an AI-powered analysis including an overall score, spam trigger detection, power word identification, mobile truncation preview, personalization checks, and actionable suggestions to improve open rates.

**How the scoring works**

The analyzer evaluates your subject line across multiple dimensions and combines them into a single 0-100 score. Length scoring rewards lines between 30-50 characters (the sweet spot for desktop email clients) and penalizes lines over 60 characters (which get truncated on most mobile devices). Word count analysis checks whether you have enough substance to be compelling without being overwhelming. Personalization detection looks for merge-tag-style placeholders like [Name] or dynamic patterns that indicate audience targeting.

**Spam trigger detection**

The tool checks your subject line against a database of known spam triggers — words and phrases that email providers (Gmail, Outlook, Yahoo) use as signals to route messages to the spam folder. Common triggers include ALL CAPS words, excessive exclamation marks, urgency phrases ("Act Now!", "Limited Time!!!"), deceptive formatting, and known spam keywords. When triggers are found, the tool suggests specific alternatives that convey the same message without raising spam filters.

**Power words and emotional analysis**

Power words are terms that have been shown through A/B testing to increase email open rates. Examples include "proven", "exclusive", "essential", "secret", "guaranteed", and "ultimate". The analyzer identifies power words in your subject line and flags their impact. Emotional analysis categorizes your subject line as positive, negative, neutral, curiosity-driven, or urgency-driven, helping you understand the psychological impact of your word choices.

**Mobile truncation preview**

Over 60% of emails are opened on mobile devices. The analyzer shows a simulated mobile preview of how your subject line appears on a typical phone screen, including where it gets truncated. This helps you ensure that the most important information appears in the first 30-40 characters.

**Common use cases**

Email marketers test subject lines before sending campaigns. Growth teams A/B test multiple variations. Newsletter authors optimize their subject lines for higher engagement. Sales professionals craft subject lines that get replies instead of being ignored. E-commerce managers write subject lines for abandoned cart emails, flash sales, and product launches.

**Privacy**

All analysis runs locally in your browser. Your subject lines are never uploaded or stored.

More examples

Examples

Marketing email

Input

5 Proven Ways to Boost Your Productivity

Output

Score: 85 — Has number, personalization, power word "proven"

Spam-like subject

Input

FREE!!! Act Now Limited Time Offer

Output

Score: 15 — Multiple spam triggers, ALL CAPS risk

Frequently Asked Questions

How is the score calculated?: The score considers length (30-50 chars ideal), word count, personalization, power words, spam triggers, and formatting. Each dimension is scored independently and combined into a weighted overall score. Higher scores indicate better predicted open rates.
What are spam triggers?: Words and phrases that email providers may flag as spam: "FREE", "Act Now", "Limited Time", ALL CAPS, excessive exclamation marks, and deceptive formatting. Our analyzer detects these and suggests alternatives.
Is my email data sent anywhere?: No. All analysis runs entirely in your browser. Nothing is uploaded or stored.
What is the ideal subject line length?: 30-50 characters for desktop email clients. On mobile (where 60%+ of emails are opened), subject lines truncate after roughly 35-45 characters. Put the most compelling information in the first 30 characters.
What are power words and why do they matter?: Power words are terms proven through A/B testing to increase open rates: "proven", "exclusive", "essential", "secret", "guaranteed", "ultimate", "surprising". They trigger curiosity, urgency, or desire that compels the recipient to open.
Should I use emojis in subject lines?: Emojis can increase open rates by 10-15% in some industries but can also appear unprofessional in B2B contexts. Test with your specific audience. Avoid using multiple emojis or using them as a substitute for compelling copy.
Does personalization really improve open rates?: Yes. Studies consistently show that subject lines including the recipient's name or other personal details see 20-30% higher open rates. The analyzer checks for personalization patterns and suggests where to add them.
How accurate is the score at predicting open rates?: The score is a heuristic based on established email marketing best practices and research. It is a useful guide for optimization but actual open rates depend on your sender reputation, audience, send time, and many other factors beyond the subject line alone.

Learn More

Related Guides

Email Subject Line Optimization: Data-Driven Tips for Higher Open Rates

6 min read

Optimizing Content for Search: Titles, Meta Descriptions, and Headlines

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