"5 vs. Five": The science behind the use of numbers in ads

Why presenting digits vs. words can boost your sales and credibility

Customers are exposed to numerical information all the time:

Gaviscon 7 symptoms of heartburn and indigestion

Domino’s 20-minute delivery guarantee

Too Good To Go impact and numbers (350+ million meals saved!)

But do consumers react differently when numbers are presented in different formats?

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🔍 Recent research shows that consumer judgments and behavior are positively influenced when numerical information is communicated in digits rather than words (e.g. “5 grams of protein” vs. “Five grams of protein”).

The researchers labelled this phenomenon the “number format effect”.

The reason the number format effect occurs is that number words feel less 'right' compared to digits, affecting customer judgments and behavior.

This might be something we've always believed to be true, but now we have scientific evidence to support our claims.

The effect was demonstrated across variety of consumer contexts, such as:

• consumer reviews

• product attributes

• the number of years a business has been in operation

• nutritional information

• public health recommendations

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🔬 The experiments

To test the hypotheses, the research group conducted six experimental studies, two online ad campaigns, and one large database analysis on more than 70 million Amazon reviews.

Here, I’ll highlight three.

1. 👗👔 In one experiment, they conducted a Facebook display ad campaign for an online clothing retailer in a real consumer behavior context.

🔬 The click-through rate (CTR, i.e. clicks/impressions) was higher for ads that communicated numerical information in digits vs. number words (CTR digits = 1.92% vs. CTR words = 1.35%).

2. 🧃In another experiment, participants shown the pictures below reported that digits (on the left) felt more accurate that number words (on the right). 🔬 Specifically, digits felt 15.6% more “right”.

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3. 🍫 In a third experiment involving energy bars, the researchers found that when source credibility is low, participants reported a greater likelihood of purchasing the energy bar when the information was presented in digits (🔬 +29% vs. number words).

However, when the source credibility was high, the difference between the two formats was attenuated.

Essentially, when consumers are skeptical of marketing practices, digits work much better than number words.

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🧠 Why does this happen?

• Digits are usually the norm when communicating numerical information. They are the main representation of quantity in calculators, measuring devices (e.g. weight scales), and point-of-sale systems.

• Past research shows that ease of processing increases liking and reduces risk perceptions.

• When we see numbers, they feel more accurate and natural in digits form compared to words.

• Therefore when marketing communications use digits (vs. number words) consumers perceive it as feeling more right, which ultimately positively affects judgments and behavior.

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Here’s what you might have missed recently on ‘Getting Better’:

• How to make an immediate impact in a new job

• Say "thank you" instead of "sorry" when mistakes happen

• First impressions last: in psychology, marketing, and everyday life

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💼 How this can help me?

Now you know: it’s better to write numbers in digits (e.g. “5”) instead of words (e.g. “five”) in banners, ads, product descriptions, and when presenting reviews.

If you’re writing copy, you know what to do.

Additionally, when building credibility (e.g. for a new or lesser-known brand), this is even more important. Customers will more likely use feelings to guide their intentions, and therefore show more appreciation when seeing numbers in digits.

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Thanks to Marisabel Romero for sharing the paper with me.

See you all next Sunday 🗓️
Thanks,
Giacomo