Digits Convert Higher Than Words

Which is better: 5 or five?

Popular guidelines encourage the latter:

...use numerals to express numbers 10 and above, and use words to express numbers zero through nine (APA Style)

But is that persuasive? Maybe not.

Turns out, digits convert better than number words (Romero, Craig, Mormann, & Kumar, 2024).

It happened in:

• Facebook Ads (e.g., 5 grams of protein)
• Amazon Reviews (e.g., 5 stars)
• Product Features (e.g., 3 free toppings)

Use digits in copywriting, even if you're breaking writing guidelines.

Caveat #1: Expertise

Do you sell expertise?

Then your customers want complexity.

So they'll prefer visual complexity:

• Obscure fonts (Thompson & Ince, 2013)
• Ugly faces (Peng, Cui, Chung, & Zheng, 2020)
• Long brand names (Kelly, Springer, & Keil, 1990).

Those traits "feel right" because they mimic the complexity that customers are seeking.

Perhaps your prospects would prefer a "thirty-minute" consultation because it feels like more time or complexity is crammed inside that duration.

Caveat #2: Narrative Contexts

Most writing guidelines allow digits in exempted scenarios.

You can show them in:

• Measurements (e.g., 5-mg)
• Time (e.g., 3 days)
• Scores (e.g., 6 out of 7)

Unfortunately, the study used these exempted contexts (e.g., 5 grams).

So it's not entirely surprising that customers expected to see digits — since digits were the expected formats.

Perhaps the effect reverses in linguistic-driven contexts (e.g., I'll have two).

• Kelly, M. H., Springer, K., & Keil, F. C. (1990). The relation between syllable number and visual complexity in the acquisition of word meanings. Memory & cognition, 18(5), 528-536.
• Peng, L., Cui, G., Chung, Y., & Zheng, W. (2020). The faces of success: Beauty and ugliness premiums in e-commerce platforms. Journal of Marketing, 84(4), 67-85.
• Romero, M., Craig, A. W., Mormann, M., & Kumar, A. (2024). Are ‘10-Grams of Protein” Better than’Ten Grams of Protein”? How Digits versus Number Words Influence Consumer Judgments. Journal of Consumer Research, ucae030.
• Thompson, D. V., & Ince, E. C. (2013). When disfluency signals competence: The effect of processing difficulty on perceptions of service agents. Journal of Marketing Research, 50(2), 228-240.