We can all agree that a well-crafted headline is one of the most critical ingredients for success in content marketing. This can make the task of headline writing seem rather daunting at times, especially since what constitutes a “well-crafted headline” is still an enigma to many.

Fortunately, click-through data has the power to eliminate a lot of the guesswork and provide us with actionable insights for headline optimization.

Of course, there are several aspects of headline writing that click-through data can inform, but today we’re going to focus in on headline length. There is a tremendous range of headline lengths for digital content and little consensus on what works best.

Taking a look at all of the paid links that were added to Outbrain’s network on Wednesday, July 10th, the number of words in the headlines range from 1 to 23, averaging around 7.

To better understand how headline length impacts engagement, we first analyzed 8 months worth of click through data on over 100,000 English headlines for paid links that ran in Outbrain’s network.

We found that moderate length performs best, with engagement declining as headlines approach either the shorter or longer end of the spectrum. As you can see in the graph below, headlines with 60-100 characters earn the highest click-through rates and these rates decline as headlines decrease below 60 characters or increase beyond 100 characters.

When measuring headline length by the number of words, rather than characters, we found the same pattern of results. The highest click-through rates were again achieved at moderate headline lengths, with 10-18 word headlines performing significantly better than headlines of any other word length.

While our results showed us that moderate length drives the most engagement with English headlines, the question remained whether this would hold true for headlines in other languages. So, we pulled a sample of over 100,000 French, Spanish and Italian headlines for paid links that ran in Outbrain’s network over the past 4 months to see how the effect of headline length varies across languages.

It turns out the relationship between headline length and engagement among French and Italian titles is very similar to what we found among English headlines.

Just like English headlines, French headlines perform best when they are between 60 and 100 characters. Italian titles have a slightly larger range of optimal performance, with 40 – 100 character headlines reaching the highest click through rates.

Spanish headlines, on the other hand, continue to perform better and better as their length increases. The longest Spanish headlines (101 – 120 characters) generated the most engagement.

When measuring headline length by the number of words, we found the same pattern of results. French and Italian headlines again perform best when their word count is within a moderate range. The optimal number of words is slightly greater (13 – 15) for French titles than for Italian titles (7 – 12), though.

For Spanish headlines, engagement increases as the number of words in the headline increases, with the longest headlines (19 – 21 words) performing best.

It’s interesting to see how optimal headline lengths differ between languages. Surely there are other variables that interact with headline length. For example, content category – do longer headlines perform better on entertainment content than on sports content? Be sure to check back for more research going deeper into headline length and covering the impact of other headline attributes on engagement.