Q: Should you highlight the dollar amount saved or percentage discount in an email subject line?

Not too long ago we took a closer look at whether displaying a dollar amount in an email subject line would increase the open rate. What intrigued us the most was how the word “save” carried a unique concept and takeaway. But saving money can be conveyed as both a dollar amount and a percentage discount. So which one works best?

The Goods
We used the same sample as last week to find our answer but limited our analysis only to emails that included the word “save” in the subject line which was just over 1,300 campaigns sent to 30,000,000 recipients. To isolate the uses of each combination, we looked at subject lines that included only a dollar amount, only a percentage, both, and neither. Here’s what the results looked like.

The first thing we see is the same trend as last week: tying a dollar value to a reference to savings saw more opens. What was interesting, however, was that referring to a percentage savings performed the poorest of all.

What This Means
Last week we suggested that telling too much of the story would let people make a decision about your offer without having to open the email. What we’re now wondering is if this data suggests a point where you aren’t telling enough.

While a dollar saving formula only lacks the original price, the percentage discount lacks the original price and dollar savings equivalent. But whether the x-factor is mental math, overuse of percentage savings in marketing, or something else entirely is tough to tell.

Rolling Like a River
The Stash rolls on next week with another insight like this one. Stick your email below if you don’t want to miss when another round of tasty marketing tidbits is published.