Numbers in larger fonts are more persuasive

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📝 Intro

You’ve spent hours putting together the benefits you want to highlight for your new product: 12-hour battery, 90% recycled, 5 different usage modes.

You wonder whether it’s a good idea to highlight those numbers, perhaps by making them bigger so they stand out. Would it make the ad more effective?

Science says that yes, it would. Here is why.

P.S.: When you’re running promotions, like a sale or limited time offer, using italic fonts increases the sense of urgency and people’s willingness to buy.

Want hundreds more insights like these? Explore all Science Says insights here.

Bigger font sizes make numbers seem cheaper and more convincing

Topics: Ads | Messaging & Copy
For: B2C. Can be tested for B2B
Research date: January 2025
Universities: Huaqiao University, China

📈 Recommendation

Write numbers that you want to highlight in a larger font size than the surrounding text. Use this in your ads, social media, website, and packaging for numbers such as:

• Prices ($9.99 per month)

• Benefits (e.g. kills 99% of bacteria)

• Features (e.g. 5,500 mAh battery for a cellphone)

People will perceive your product as cheaper, be more convinced of how effective the feature you’re highlighting is, and will be more willing to buy.

🎓 Findings

• When a number is displayed in a larger font size than the surrounding text, people find it more convincing. If it’s the price, they find it more affordable. This makes people more likely to consider buying the product.

• As part of 4 experiments, researchers found that:

  • When the price was written in a larger font, the price of a lamp was considered 9.3% cheaper and a bottle of wine 15% cheaper

  • When a number about a key product feature was shown in a larger font to people, they:

    • Found a fitness tracker’s 60m waterproof feature 16.4% higher quality and were 25.9% more willing to buy it

    • Rated a vacuum cleaner’s 18,000 Pa suction power 16.4% higher and were 18.2% more willing to buy it

    • Thought a sunscreen’s 50+ SPF rating was 11.3% higher and were 12.5% more likely to buy it

• The effect disappears for well-known brands or premium products.

🧠 Why it works

• When we see a number or statistic in a larger font, it’s more visible and stands out. 

• This makes us assume the brand must be confident of the message to make it more prominent.

• This confidence makes the message stronger in our minds, making us trust the message more and consider it more persuasive.

• When a brand is already well known in our minds, or has a strong brand identity, we don’t rely on visual aspects like font size to guide our decision-making, as we already have an opinion of the brand. This weakens the effect of larger fonts for numbers.

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✋ Limitations

• While the study looked at prices and key features, it didn’t look at whether writing discount amounts (e.g. 25% off) larger affects how the discount is perceived. 

• The research was done entirely on Chinese customers. It’s possible, but unlikely, that the effect varies across other cultures and contexts, such as in the US and Europe.

• The study looked only at highlighting numbers. It did not test the effect on highlighting words or other design elements (e.g. symbols).

• It’s unclear if there is a certain size proportion at which the effect is strongest. It’s possible that exaggerating the size of numbers too much compared to the body text might lead to negative effects.

🏢 Companies using this

• Using a larger font for numbers is common in retail, including for groceries, electronics, clothes and other items. This is most often used to highlight discounts or prices, particularly for brands seeking to portray themselves as cost effective.

• Companies frequently use larger numbers to highlight:

  • Sale prices or discount percentages

  • Awards or ratings (e.g. Sensodyne highlighting its position as the #1 Dentist recommended brand)

  • Key statistics about the product (e.g. Dettol’s 3x antibacterial cleaning power)

• High-end or luxury brands tend to, correctly, not highlight their numbers in larger sizes.

Orange juice brand Tropicana correctly highlights in a large font that it uses 17 oranges. This will help for those unfamiliar with the brand. However, claiming that it is 100% juice may backfire.

⚡ Steps to implement

• Look at your current messaging to see where and how numbers are being used including for prices, discounts, product specifications, awards or product metrics.

• When you showcase these numbers, increase the font size relative to other text appearing alongside it to make it noticeably larger. You can A/B test different font sizes, to find the size that works aesthetically, while still highlighting the number.

• Use this across your branding and marketing materials, including on your website and social media pages as well as on physical advertising and in-store branding and signage.

• If you’re a well known brand, sell premium products and services or have a high price point, this is less likely to make a big impact.

🔍 Study type

Online experiments.

📖 Research

Numbers Speak Louder When They Are Larger: The Impact of Font Size on the Persuasiveness of Numerical Stimuli in Advertising. Journal of Consumer Behaviour (January 2025)

🏫 Researchers

Yunzhi Huang, Huaqiao University, China

Remember: This is a new scientific discovery. In the future it will probably be better understood and could even be proven wrong (that’s how science works). It may also not be generalizable to your situation. If it’s a risky change, always test it on a small scale before rolling it out widely.

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🎓 It took 3 of us 11 hours to accurately turn this 11 page research paper into this 3min insight. 

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