Imagine trying to read a book where the text is so small you have to squint and hold it inches from your face, or so large that you can only see two words at a time. You'd probably put the book down and find something else to read. The same thing happens on websites—when text is too small or too large, people simply leave and find content that's easier to consume.
Font size is one of the most fundamental aspects of web design, yet it's often overlooked or treated as an afterthought. The size of your text directly impacts whether people can comfortably read your content, how long they stay on your pages, and whether they'll return to your website in the future. It's not just about aesthetics—it's about creating an accessible, user-friendly experience that works for everyone.
Several factors make proper font sizing crucial for modern websites:
Text that looks perfectly readable on a desktop computer can become unreadable when viewed on a mobile device. What appears as comfortable 12px text on a large monitor becomes tiny, squint-inducing text on a phone screen, forcing users to zoom in or simply give up on reading your content.
Font sizes can be measured in several different units, each with its own advantages:
Pixels provide absolute sizing that remains consistent across devices. A 16px font will always be 16 pixels tall, regardless of the user's browser settings or device type.
These units scale relative to other elements or the root font size, making them more flexible for responsive design and better for accessibility.
Percentage-based sizing scales relative to the parent element, offering flexibility but potentially creating inconsistent results across different page sections.
These newer units scale based on the viewport size, allowing text to grow and shrink with the screen size, though they require careful implementation to remain readable.
What's happening: Your website uses font sizes that look fine on desktop but become unreadable on mobile devices, forcing users to zoom in to read content.
User Impact: Visitors leave your site immediately because the content is too difficult to read, leading to high bounce rates and lost conversions.
Simple solution: Use a minimum of 16px for body text on mobile devices. Test your website on actual mobile devices to ensure text remains comfortable to read without zooming.
What's happening: Different pages or sections of your website use different font sizes for similar content, creating an inconsistent reading experience.
User Impact: The inconsistency makes your website feel unprofessional and can confuse readers about the hierarchy and importance of different content.
Simple solution: Establish a typography scale with consistent font sizes for headings, body text, captions, and other text elements, then apply it consistently across your entire website.
What's happening: Headings, subheadings, and body text are too similar in size, making it difficult for readers to understand content structure and importance.
User Impact: Readers struggle to scan content quickly and may miss important information because the visual hierarchy doesn't guide their attention effectively.
Simple solution: Create clear size differences between heading levels and body text. Main headings should be significantly larger than body text, with each subsequent heading level being progressively smaller but still larger than body text.
What's happening: Important information like terms of service, privacy policies, or technical specifications is displayed in extremely small text that's difficult to read.
User Impact: Users can't effectively read important information, potentially leading to misunderstandings or legal issues, and creating poor user experience.
Simple solution: Use the same minimum font sizes for all content, including legal text. If you need to differentiate secondary information, use color, spacing, or styling rather than making text smaller.
Most browsers default to 16px for body text, and this size has been extensively tested for readability across devices. Use this as your starting point and adjust based on your specific font and design needs.
Don't rely solely on desktop browser testing. Check your font sizes on actual mobile devices, tablets, and different screen sizes to ensure they remain readable in real-world conditions.
If your audience includes older adults or people who might have vision difficulties, consider using larger font sizes (18-20px) for body text to improve accessibility and user experience.
Establish consistent font sizes for different content types: main headings (32-48px), subheadings (24-32px), section headings (20-24px), body text (16-18px), and captions (14-16px).
Different fonts appear larger or smaller at the same pixel size. Sans-serif fonts often need to be slightly larger than serif fonts, and decorative fonts may need significant size adjustments for readability.
Consider using em or rem units instead of pixels to allow your text to scale better with user preferences and different devices, improving accessibility and responsive design.
For long-form content that people will read extensively, use 18-20px for body text on desktop and never smaller than 16px on mobile. Larger text reduces eye strain during extended reading sessions.
E-commerce sites should use at least 16px for product descriptions, with key information like prices and specifications being even larger and more prominent.
Navigation elements should be large enough to tap easily on mobile devices (minimum 16px) while remaining proportional to your overall design.
Form labels and input text should be at least 16px to prevent mobile browsers from zooming in when users focus on form fields, which can disrupt the user experience.
Button text should be large enough to read quickly and tap easily, typically 16-18px minimum, with adequate padding around the text.
Research in typography and cognitive psychology provides clear guidance on optimal font sizes:
Google and other search engines consider user experience factors when ranking websites, and font size plays a role in these assessments:
Business sites often use overly small text for legal disclaimers, contact information, and service descriptions, making important information difficult to access.
Online stores frequently use tiny text for product specifications, shipping information, and return policies—exactly the information customers need to make purchasing decisions.
Content sites sometimes prioritize fitting more text on the screen over readability, using font sizes that work against their goal of engaging readers.
Creative professionals often sacrifice readability for visual design, using artistic fonts or sizes that look good but are difficult to read.
Use these methods to evaluate and improve your website's font sizing:
Use your browser's developer tools to test different font sizes in real-time and see how they look on various device sizes.
Test your website on actual smartphones and tablets to experience how your font sizes feel in real-world usage scenarios.
Use tools like WAVE, axe, or Lighthouse to check for accessibility issues related to text size and readability.
Ask real users, particularly those in your target demographic, to read content on your website and provide feedback on text readability.
Monitor user behavior metrics like bounce rate, time on page, and scroll depth to identify potential readability issues.
Beyond basic sizing, consider these advanced factors for optimal typography:
Investing in proper font sizing delivers measurable business results:
In a world where people consume most content on small screens while multitasking, distracted, and often in less-than-ideal lighting conditions, font size becomes a critical factor in whether your message gets through. It's not enough for your content to be well-written and valuable—it also needs to be physically comfortable to read.
The good news is that optimizing font size is one of the most straightforward improvements you can make to your website. Unlike complex technical optimizations, adjusting font sizes is simple, immediate, and has an instant impact on user experience. The challenge isn't in implementing the changes—it's in recognizing that what looks good to you on your desktop computer might be completely unreadable to someone browsing on their phone during their commute.
Remember that readable text is inclusive text. When you choose font sizes that work for people with aging eyes, visual impairments, or small mobile screens, you're creating a better experience for everyone. In an increasingly competitive digital landscape, the websites that prioritize user comfort and accessibility are the ones that build lasting relationships with their audiences.
Greadme's analysis tools can help you identify text that might be too small for comfortable reading and provide specific recommendations for improving typography across your entire website.
Optimize Your Font Sizes Today