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Subject Line Research: Response Goes Down As the Characters Go Up

The issue of subject line length is something that gets debated endlessly around the marketing water cooler. Most people know that anything longer than 55 characters (and, just a reminder, the spaces do count!) will get cut off. And many have heard the maxim that 35 is really a better number to aim for. But, does anyone know how the length of the subject line actually affects response?

Response rate (as measured by clicks) goes down dramatically when the subject line is longer than 50 characters.

Click-through rates for subject lines with 49 or fewer characters were 75 percent higher than for those with 50 or more.

What about open rates? While the difference wasn’t as dramatic, we found that subject lines with 49 or fewer characters had open rates 12.5 percent higher than for those with 50 or more.

Testing your subject lines on your list is the only way to know what will work and what won’t. But, this research clearly shows that, in fact, brevity is the better part of valor.

I promise to add to this blog entry with the source of this study.