Email Subject Line Tester
Type a subject line and see its score, word and character counts, and the checks it passes.
The score is a rough guide only, not a real deliverability test — whether your mail reaches the inbox depends on sender reputation, list quality and the receiving provider.
Nothing you type is saved or sent anywhere — everything stays in your browser.
How to use this email subject line tester
This email subject line tester scores any subject line you type, so you can see at a glance whether it is likely to catch a reader’s eye or end up ignored. You do not need an account, and nothing you type is saved or sent anywhere — everything happens in your browser.
Step 1: Type or paste your subject line into the box above.
Step 2: Read the score out of 100, along with the character and word counts.
Step 3: Work through the checklist underneath. Fix the checks marked with an ✗, then test the new version.
Worked example
Take the subject line “Your 5-point plan to save 20% this week”. It has 39 characters and 8 words, so it earns 25 points for length and 15 for word count. It contains a number, which adds 10, and it uses “your”, which adds another 10. It has no spam words (+15), no word in ALL-CAPS (+10) and no more than two exclamation marks (+5). That is 90 out of 100 — a Strong score.
A weaker example is “FREE cash prize winner act now!!!”. It is the right length and word count, so it still earns 25 points for length and 15 for word count, but it scores nothing for the number, question or “you” checks. It is packed with five spam words — free, cash, prize, winner and act now — so the spam check scores zero, “FREE” is an ALL-CAPS word, and the three exclamation marks break the punctuation check. That leaves 40 out of 100 — Needs work.
How long should a subject line be
About 30 to 60 characters is the sweet spot. That is long enough to say something useful, and short enough to show in full on a phone, where most people read their mail. Under 20 characters usually says too little, and over 70 characters gets cut off in most inboxes, so put the most important words first — never leave the key detail at the end.
Spam words
Some words are linked to unwanted mail, because spammers use them so often. This tester watches for ten of them: free, winner, guaranteed, act now, cash, prize, urgent, buy now, click here and limited time. Each one found costs 10 points from the spam check, which starts at 15 and never drops below zero. One spam word does not doom a subject line by itself — the checklist shows exactly which words were found, so you can decide whether to keep them or swap them for plainer words.
Frequently asked questions
What makes a good subject line?
A good subject line is short, specific and honest. Aim for 30 to 60 characters, promise one clear benefit, speak to the reader with words like “you” or “your”, and skip spam words, ALL-CAPS and piles of exclamation marks.
How long should a subject line be?
About 30 to 60 characters. That length shows in full on most phones and desktop inboxes, while still saying something useful. Shorter lines often say too little, and longer ones get cut off before the reader reaches the point.
Do spam words always send mail to spam?
No. One word rarely decides it — whether mail reaches the inbox depends far more on sender reputation, list quality and the receiving provider. Spam words only raise the risk, especially when several appear together.
Should I use emojis in subject lines?
An emoji can help a subject line stand out, but use at most one, and never let it carry the meaning on its own — some mail apps show a blank box instead. Keep the words strong enough that the subject line works without the emoji.
Is the score a real deliverability test?
No. The score is a rough guide only, not a real deliverability test — whether your mail reaches the inbox depends on sender reputation, list quality and the receiving provider.