Our Mission: True 1:1 Scale Everywhere
Almost everyone has experienced the frustration of needing to measure something small—a screw, a ring, a button, a piece of jewelry, or a craft pattern—only to find no tape measure or physical plastic ruler in sight.
While augmented reality (AR) smartphone camera apps have become common, they suffer from optical distortion, lens curvature, hand tremor, and depth estimation errors ranging between 2% to 5%.
Try Online Ruler takes a fundamentally different engineering path: your display screen is already a flat, laser-precise grid of physical pixels. By accurately determining your screen's hardware Pixels Per Inch (PPI), we can render vector tick marks directly on your screen glass where 1 cm or 1 inch is identical to an optical laboratory scale.
How Calibration Works
Standard web browsers only expose arbitrary CSS pixels (typically scaled at 96 DPI for standard desktops or 2x/3x for high-DPI Retina/AMOLED phones). To establish a true physical baseline, Try Online Ruler offers three calibration methods:
ISO Bank Card
All payment cards worldwide comply with ISO/IEC 7810 ID-1 (exactly 85.60 mm × 53.98 mm). Matching your card yields exact screen PPI instantly.
250+ Device Profiles
Our database stores factory hardware PPI for MacBook Pro/Air, iMacs, Surface tablets, Dell XPS, iPhones, Samsung Galaxy, and desktop monitors.
Diagonal Input
Enter your manufacturer's screen diagonal (e.g. 15.6", 24", 27", 34") to calculate pixel pitch geometrically using Pythagorean display ratios.
Engineering & Precision Standards
Designed for engineers, crafters, graphic designers, educators, and everyday users who demand uncompromising accuracy:
✓ ISO 7810 Standard
Physical credit card dimensions calibrated down to ±0.05 mm precision.
✓ Zero Parallax Distortion
Screen glass contact measurement eliminates camera lens angle & lighting errors.
✓ 100% Client-Side Privacy
Zero data collection, no telemetry tracking, and zero measurement history storage.
✓ Sub-Pixel Vector Engine
HTML5 Canvas high-DPI rendering supports 4K, 5K, Retina, and OLED displays flawlessly.