Free tool
Subject line tester
Score a cold email subject line out of 100 and see how it looks in a phone inbox before you send it.
Six checks
- Length and words
- 40 points
- Spam, capitals, punctuation
- 50 points
- Personalisation
- 10 points
Your subject line
Checks
- LengthPass44 characters. Short enough to read at a glance.25/25
- WordsPass7 words. Easy to take in at a glance.15/15
- Spam wordsPassNo spam trigger words.20/20
- CapitalsPassNormal case, like a person writing.15/15
- PunctuationPassPlain punctuation.15/15
- PersonalisationPass2 merge fields, filled in with sample values in the preview.10/10
How it works
Six checks, scored out of 100
The ranges are ZicReach's guide for cold email, where a subject should read like a note from a person.
- 01
Type the subject
Merge fields such as {{first_name}} or {{company}} are filled with sample values for the length count and the preview.
- 02
Six checks
Length (25 points: 20 to 50 characters in full), words (15: 2 to 7), spam words (20: 10 off each), capitals (15), punctuation (15: exclamation marks, !!, currency signs, emoji and a fake Re: or Fwd:) and personalisation (10).
- 03
See it on a phone
The preview cuts the subject where a narrow inbox would, next to your preview text, so you can check the important words come first.
FAQ
Questions, answered
Short answers about the subject line tester.
How long should a cold email subject line be?
Short enough to read at a glance and to show on a phone. The tester gives full marks from 20 to 50 characters and 2 to 7 words, and the preview shows where a narrow screen cuts it.
Should I personalise the subject line?
A first name or company name in the subject shows the email was written for the reader. Use merge fields with a fallback, such as {{first_name|there}}, so an empty field never shows.
Is it OK to start with Re: or Fwd:?
Not on a first email. It suggests an earlier conversation that never happened, which readers notice and some filters penalise. Follow-ups sent in the same thread get a real Re: on their own.
Is a high score a guarantee of opens?
No. The score checks the things you control in the subject line. Opens also depend on who you send to, your sender name, your domain's reputation and whether the email lands in the inbox.