Email Subject Line Tester: Free Score out of 100
Type an email subject line to get a score out of 100 with a checklist: length up to 60 characters and 9 words, punctuation, emoji, spam words, capitals, personalisation and numbers. See how it looks on a phone and a computer, and compare up to five variants for an A/B test. Free, and nothing leaves your browser.
The score updates as you type. Put each variant on its own line; the best one is marked. Merge tags such as {first_name} or *|FNAME|* count as personalisation. Your draft is kept in this browser until you start over.
What the tester checks
| Check | Points |
|---|---|
| Length: 20–60 characters (61–70: 12 points) | 25 |
| Words: 3–9 | 10 |
| Punctuation: 3 marks or fewer | 10 |
| Emoji: 1 or none | 5 |
| Spam words: none from the spam checker’s list | 25 |
| Capitals and formatting: no SHOUTING, “!!” or fake “Re:” | 10 |
| Personal: a merge tag or “you” | 8 |
| Specific: a number or one question | 7 |
| Total | 100 |
Example
| Subject line | Score |
|---|---|
| {first_name}, 3 ideas to shorten your sales cycle | 100 |
| Quick question about Acme? — clear, but not personal | 92 |
| FREE OFFER!!! Act now — spam words, capitals, “!!!” | 39 |
The first subject is 49 characters and 8 words, uses the reader’s name and promises something concrete. The third would score 50 on form alone, but its spam words and capitals cap it at 39. Click Load example to see every check.
Write subject lines that get opened
Say what is inside and why it matters to the reader, put the key words in the first 40 characters, and keep the promise in the email itself. In sales emails a plain, specific subject usually beats a clever one: name the company, the problem or the meeting. Check the whole email with the email spam checker before you send it, and find the right address with the email format finder.
Frequently asked questions
How long should an email subject line be?
Keep it to 60 characters and 9 words or fewer, as Mailchimp recommends. Phones show only about the first 40 characters in the inbox, so put the most important words first. Very short subjects work too, as long as they say what the email is about.
How is the score calculated?
Each subject starts from eight checks worth 100 points: length 25, words 10, punctuation 10, emoji 5, spam words 25, capitals and formatting 10, personal 8 and specific 7. Strong spam signals cap the score at 39, because the email may not reach the inbox at all.
Which words make an email go to spam?
Words that sound like scams or hard selling, such as “act now”, “free money”, “guaranteed” or “verify your account”, especially in capitals and with “!!!”. The tester uses the same list of about 300 words as the email spam checker and suggests a calmer word for each.
Should I use emoji in a subject line?
One emoji can help a subject stand out in a busy inbox, but use it next to words, not instead of them, and test how it looks on phones and computers. More than one emoji looks like promotion and lowers the score.
How do I A/B test subject lines?
Write two to five variants, score them here and keep the two best. Send each to a small random part of your list, for example 10% each, wait a few hours, then send the subject with the higher open or reply rate to everyone else.
Is what I type stored or sent anywhere?
No. The scores are worked out in your browser and the draft is kept only in this browser so you can come back to it. Nothing you type is sent to SalesBond or anyone else, and no AI reads it. Click Start over to clear it.
Related tools: email spam checker, mailto link generator, email format finder. More on sales and running a sales team on the SalesBond blog and the home page.
Official sources
- Mailchimp: best practices for email subject lines — no more than 9 words and 60 characters, 3 punctuation marks and 1 emoji.
- Gmail Help: email sender guidelines — subject lines must not be misleading or deceptive.
Updated on Nov 6, 2026. This calculator is for information only and is not tax, legal or payroll advice. The score checks wording and form, not whether your list wants the email; an A/B test with real readers is the final answer.
