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Email Subject Line Tester

100% Free

Score your email subject line in real time — length, spam triggers, emoji, ALL CAPS, power words, and an open-rate hint.

Live Score
Spam Check
100% Client-Side
No Sign Up
39 characters6 words
87/ 100
Excellent

Above average — strong open-rate potential

Length
39 chars
6 words · Ideal
Spam words
0
None detected
Emoji
0
Within a good range
ALL CAPS
None
No shouting
Power words
3
exclusive, your, guide
Urgency
0
None detected

Suggestions

  • A light touch of urgency ("today", "now") can lift opens — use sparingly.
  • Consider adding a specific number (a stat, a list count) — numbers stand out in the inbox.
  • Add preview/preheader text — it complements the subject and adds context in the inbox.

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Add Email Subject Line Tester to your website or blog in seconds.

  • Responsive design
  • Lightweight & fast
  • No backend required
  • Always up-to-date 
<iframe
  src="https://tools.town/embed/email-subject-tester/"
  width="100%"
  height="600"
  style="border:none; border-radius:12px;"
  loading="lazy"
  title="Email Subject Line Tester">
</iframe>

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How to Use

  1. 1 Type or paste your email subject line into the box
  2. 2 Optionally add your preview / preheader text
  3. 3 Watch the score and metric cards update as you type
  4. 4 Review flagged spam words, emoji, and ALL CAPS usage
  5. 5 Apply the suggestions and re-test until the score is strong

Features

  • Live 0–100 score that updates as you type
  • Ideal-length check tuned for inbox previews (~30–50 characters)
  • Spam-trigger word detection from a built-in list
  • Emoji count and ALL CAPS shouting detection
  • Power-word and urgency-word spotting
  • Actionable suggestions plus an open-rate hint
  • Runs entirely in your browser — nothing is uploaded

Why it Matters

The subject line decides whether your email gets opened at all — most readers judge it in a fraction of a second. A line that's too long gets cut off, spam-trigger words sink deliverability, and ALL CAPS reads as shouting. Scoring the line before you hit send turns guesswork into a quick, repeatable check.

★★★★★

Use Cases

Marketing Campaigns

Test newsletter and promo subject lines before you broadcast

Boost Open Rates

Spot length and spam issues that quietly suppress opens

Cold Outreach

Keep sales and recruiting subjects clear, short, and human

A/B Variations

Compare two subject ideas and ship the higher-scoring one

What this tool does

The Email Subject Line Tester scores your subject line from 0 to 100 as you type. It checks the things that decide whether an email gets opened — length, spam-trigger words, emoji use, ALL CAPS shouting, and power or urgency words — and gives you concrete suggestions plus an open-rate hint.

How it works

As you type, the tool measures the character and word count, rates the length against the ideal inbox-preview window (~30–50 characters), scans for built-in spam triggers, counts emoji, detects ALL-CAPS words, and looks for engagement-boosting power and urgency words. Those signals combine into a single score and a list of fixes. The scoring logic is a pure function, so the same subject always gets the same score.

Privacy

Everything runs locally in your browser. Your subject line and preheader text are never uploaded, logged, or stored.

Frequently Asked Questions

What makes a good email subject line score?
Length is the biggest factor — around 30 to 50 characters reads as a complete thought and survives inbox truncation. Beyond that, the tester rewards clear power words and a light touch of urgency, and penalises spam-trigger phrases, ALL CAPS, and emoji overload. A score of 70 or higher is solid; 85 or higher is excellent.
Which spam words does it check for?
It scans a built-in list of common spam triggers such as "free", "buy now", "cash", "guarantee", "winner", "urgent", "click here", and "$$$". These don't guarantee a spam folder on their own, but stacking several of them raises your risk, so the tester flags each one it finds.
Should I use emoji in subject lines?
One or two well-placed emoji can help a subject stand out and the tester gives a small bonus for that. Three or more starts to look like spam and is penalised, so use them sparingly and make sure they render across inboxes.
Does a high score guarantee a high open rate?
No. The score is a heuristic based on length, wording, and formatting best practices — it can't see your audience, sender reputation, or send time. Treat it as a fast pre-send check, then confirm with your own A/B tests.
Is my subject line sent anywhere?
No. The tester runs entirely in your browser. Your subject line and preheader are never uploaded, logged, or stored — refreshing the page clears everything.
📖

Want to understand the math?

Browse all guides →
Writing Email Subject Lines Th
email subject line

Writing Email Subject Lines That Get Opened

A practical guide to email subject lines: ideal length, spam-trigger words to avoid, when emoji help, why ALL CAPS hurts, and how power and urgency words lift open rates.

23 Jun 2026

5 min read

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