How to Use the Font Readability Distance Calculator
Enter font size in points (pt) to see the comfortable and maximum readable distances. Add a viewing distance to get the minimum and recommended font sizes for that distance. Ideal for planning presentation slides, classroom displays, and signage.
How the Calculation Works
Based on the minimum human visual acuity angle (5 arcminutes). Since 1pt = 0.353mm, the max readable distance = font height (mm) × 687, and comfortable reading distance = font height × 172. For example, 24pt text is comfortably readable at about 19 feet (5.8m) and barely readable at up to 47.5 feet (14.5m).
Font Size Guide by Distance
Recommended minimum font sizes by viewing distance: 16ft (5m) small conference room — 18pt minimum; 33ft (10m) classroom — 35pt minimum; 50ft (15m) medium auditorium — 53pt minimum; 82ft (25m) large hall — 88pt minimum. Use 1.5× for headings and 2× for key keywords.
Monitor vs. Projector Screen
Monitors are typically used at 24 inches (60cm), so 10–12pt text is sufficient. Projector screens at 6–33 feet (2–10m) require at least 20–35pt. Viewing distance, not screen size, is the key factor for determining font size.
Frequently Asked Questions
A point (pt) is a print unit equal to 1/72 inch = 0.353mm. A pixel (px) depends on screen resolution — at 96 dpi, 1pt ≈ 1.33px. For presentations, pt is the consistent standard to use.
A common guideline: title 40pt, subheading 28pt, body 24pt, caption 18pt. Scale all sizes proportionally based on room size, using this calculator's recommended font size as the baseline for body text.