Email length doesn't affect click rate

Write as much as you need to, but no more and no less.

Justin Duke
May 4, 2023
Email length doesn't affect click rate

Introduction

Buttondown is a tool for sending newsletters of all types: marketing-y ones for Shopify stores, thought-leader-y ones for folks selling consulting services and info-products, silly ones for folks running small private newsletters.

The single most common "how do I send emails better?"-type question we get is: "how long should my emails be?"

There is a lot of folk wisdom floating around this question, often coming from well-intentioned but poorly-reasoned places. "Keep it short and sweet!" "Have exactly two CTAs, one after the third paragraph and one at the end!" "Keep people in the inbox as long as possible!"

I don't have a particularly principled answer to this question, but I do have a bunch of data...

Methodology

Here's how I collected the data:

  • I sample one hundred thousand bulk emails sent from Buttondown over the last twelve months.
  • I calculate the word count of each email, clamping it to the nearest hundred.
  • I then calculate the click rate of each email.

A couple caveats:

  • Buttondown has click tracking turned off by default. Naturally, this means the one hundred thousand emails must specifically come from newsletters who have opted into click tracking.
  • Clicks are defined as a unique tuple of "URL, subscriber" — so if a subscriber clicks the same link twice, it only counts as one click, but if they click two different links, it counts as two clicks.
  • I discarded emails with word counts below 50 and above 3000, as they were fairly noisy and did little else than clutter the final resulting graph.
  • I ignored clicks outside the context of the email itself (such as 'view on web' or 'unsubscribe' links), though I think those will be interesting for follow-up analyses

Data

You're here for the headline, not the flowery prose, so let me jump to the interesting stuff:

Unsatisfying, I know. No pretty linear relationship! No mandate to write exactly X words per email, and no more!

I think you should take this as instead as a simple lesson: write the correct number of words for your email. If you're writing a short, pithy newsletter, don't pad it out with fluff. If you're writing a long, thoughtful essay, don't cut it short because you're worried about click rate.

Further analyses

I think playing around with this dataset is fun and useful, and I plan to do more of it in the future. Here are some ideas I have:

  • How does the presence/absence of a pre-header affect open rate?
  • How does the length of a subject line affect open rate?
  • Do questions in subject lines increase open rate?

If you have any ideas, please reach out — I'd love to hear them!

Buttondown is the last email platform you’ll switch to.