How Reading Time Is Calculated: The Science Behind It

What Is Reading Time?

Reading time is an estimate of how long it takes an average person to read a piece of text. You've likely seen it on blog posts ("5 min read") or Medium articles. These estimates help readers decide whether to invest their time and set expectations before they start.

But how accurate are these numbers? And how are they calculated? Let's break down the science.

The Average Reading Speed

For English text, the commonly accepted average reading speed is:

• Silent reading (adults): 200–250 words per minute (WPM)
• Oral reading (adults): 150–180 WPM
• Skimming: 400–700 WPM (with reduced comprehension)

Most reading time calculators use 238 WPM as the baseline. This figure comes from a 2019 meta-analysis by Brysbaert et al., which reviewed 190 studies on reading speed. It's more accurate than the older 250 WPM estimate that many tools still use.

Reading Speed by Age

The Calculation Formula

The standard reading time formula is straightforward:

Reading Time (minutes) = Total Word Count ÷ Reading Speed (WPM)

For example:

• 750 words at 238 WPM = 3.2 minutes
• 2,000 words at 238 WPM = 8.4 minutes
• 10,000 words at 238 WPM = 42 minutes

Adding Buffer Time for Non-Text Content

Most modern calculators add time for images and code blocks:

Total Reading Time = (Word Count ÷ 238) + (Image Count × 0.083) + (Code Blocks × 0.5)

• Images: Roughly 5 seconds (0.083 minutes) per image — based on Medium's approach of adding 12 seconds for the first image and 11 seconds for each subsequent image
• Code blocks: About 30 seconds per block, since readers often pause to study code

Factors That Affect Reading Speed

Reading speed isn't fixed. Several factors can push it higher or lower:

Content Complexity

• Simple narrative: 250–300 WPM (novels, casual blog posts)
• Technical writing: 150–200 WPM (documentation, research papers)
• Legal/academic text: 100–150 WPM (dense jargon, complex sentence structures)

Text Formatting

• Short paragraphs: Readers move faster
• Bullet points and headers: Improve scanning speed by 25–40%
• Long unbroken blocks: Slow readers down significantly

Reader's Familiarity with the Topic

Readers fluent in a subject read 20–30% faster than newcomers. A developer reads API documentation far quicker than a non-technical project manager.

Language Proficiency

Non-native English speakers read English text 15–30% slower than native speakers. If your audience is global, consider adjusting your reading time estimates upward.

Screen vs. Paper: Does It Matter?

Yes. Multiple studies show reading speed differs between screens and paper:

Why screens slow us down:

• Eye fatigue increases on backlit displays
• Scrolling interrupts the reading flow
• Distractions (notifications, links) compete for attention
• Line length on mobile is shorter, causing more eye movements

Tips for Screen-Optimized Writing

• Keep paragraphs to 3–4 sentences maximum
• Use descriptive headers every 200–300 words
• Add white space between sections
• Bold key terms to help scanners find them

How Accurate Are Reading Time Estimates?

Reading time estimates are useful but imperfect. Here's why:

• Individual variation is huge: The slowest and fastest readers in a population can differ by a factor of 3×
• Reader behavior varies: Some readers skim, others read every word
• Content complexity is hard to quantify: A 1,000-word technical tutorial takes longer than a 1,000-word opinion piece

The best way to think about reading time: it's a benchmark, not a stopwatch. It gives readers a ballpark, which is all most people need to decide whether to click.

Reading Time for Different Formats

Related Guides

• Word Count Tips for Writing
• Text Analysis Guide
• Placeholder Text Best Practices

Try It Yourself

Want to calculate reading time for your own text? Our free word counter tool shows word count, character count, and estimated reading time instantly.

👉 Free Word Counter Tool