How It Works Results About Pricing FAQ Guarantee Blog Schedule Demo →
Free Tool

Cold Email Subject Line Grader

Paste any subject line and get an instant score across 5 data-backed criteria: length, spam triggers, personalization, curiosity, and specificity.

Overall Score
0
out of 100

Score Breakdown

Length
0/20
No Spam Words
0/20
Personalization
0/20
Curiosity
0/20
Specificity
0/20

3 Ways to Improve It

Good subject lines get opens. A solid system turns those opens into meetings. See how it works.

Schedule a Demo →

5 Tips for Subject Lines That Get Opens

1

Keep it under 8 words

Subject lines between 3 and 7 words consistently outperform longer ones in B2B cold email. Shorter lines look like messages from real people, not campaigns. Anything over 10 words starts to look like a newsletter header.

2

Use lowercase

Title Case Subject Lines Signal Mass Email. all lowercase or sentence case feels like a direct message. In tests across thousands of cold email sends, lowercase subject lines regularly outperform their capitalized equivalents by 10 to 20 percent on open rate.

3

Use a merge tag

Including {{firstName}} or {{company}} in the subject line signals personalization before the prospect even opens. It does not guarantee the email is actually personalized, but it passes the first filter. Pair it with a body that delivers on the promise.

4

Create an open loop, not a promise

Subject lines that hint at something without giving it away drive more opens than subject lines that lead with the benefit. "quick question" or "saw something on your site" creates curiosity. "3 ways to increase your revenue" promises and delivers in the subject itself, leaving no reason to open.

5

Never sound like a discount

Words like "free", "guaranteed", "limited time", and "earn" are not just spam triggers in filters. They also prime the reader to treat your email like an ad before they read a word of it. The goal is to look like a colleague reaching out, not a marketer with a quota to fill.

Frequently Asked Questions

What makes a cold email subject line effective?
The best cold email subject lines are short (3 to 7 words), feel personal, and create curiosity without being clickbait. They avoid spam trigger words like "free", "guaranteed", or "limited time", and they often include the prospect's name or company to signal the email is not a blast. Lowercase subject lines consistently outperform title case in cold outreach because they look like a message from a real person.
How does the cold email subject line grader score my subject line?
The grader scores your subject line across 5 criteria: length (ideal 3 to 7 words), spam word detection, personalization signals like merge tags or lowercase starts, curiosity and open loops from question marks or incomplete thoughts, and specificity from numbers or concrete nouns. Each category is worth up to 20 points for a total of 100. You also receive 3 specific improvement suggestions based on your lowest-scoring areas.
Does a high subject line score guarantee opens?
Not on its own. Subject lines drive opens, but open rates also depend on sender reputation, deliverability, domain warmup, and list quality. A strong subject line on a domain with poor reputation will still land in spam. The grader evaluates the subject line in isolation. For end-to-end deliverability, body copy and technical setup matter just as much.
Get Started

See Exactly How We'd
Build Your System.

15 minutes. We'll show you the research layers, the lead magnet, and the outreach sequence we'd build for your specific offer. No pitch deck, no pressure.

See How We'd Build Your System →

Guaranteed meetings every month or your money back. We put the number in the contract.