Measurement toolsEnglish
How to Use Guidelines and Selection
Use Guidelines to compare gaps and align edges. Use Selection to measure one box, including its width, height, diagonal, and area.
Leggi la guidaGuide alla misurazione su schermo
Ottieni misure migliori dallo schermo
Inizia dalla calibrazione, scegli la modalità di misura giusta o correggi un righello che non coincide con un oggetto reale.
Inizia dalla calibrazione
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Accuracy and troubleshootingEnglish
Why Is My Online Ruler Inaccurate?
Fix an online ruler that does not match a real object. Check browser zoom, calibration, display changes, and your reference object in the right order.
Leggi la guida Pixels and displaysEnglish
CSS Pixels vs Device Pixels
Learn what CSS pixels and device pixels mean, how devicePixelRatio connects them, and why neither value alone gives a physical screen measurement.
Leggi la guida Practical usesEnglish
How to Measure UI Spacing in a Browser
Measure padding, margin, gap, width, and height in CSS pixels with browser DevTools, then use Online Ruler for a visual or calibrated size check.
Leggi la guida Practical usesEnglish
How to Measure an Image’s Size on Screen
Separate image file pixels from displayed CSS size and physical screen size. Use Inspect, a short browser check, and calibrated PPI correctly.
Leggi la guida Practical usesEnglish
How to Use a Screen Ruler on a Phone
Set up and calibrate a screen ruler on a phone, choose a reference that fits, and use Guidelines or Selection without losing scale after rotation.
Leggi la guida Pixels and displaysEnglish
PPI vs DPI: What’s the Difference?
Learn the difference between PPI and DPI, when to use pixels per inch or dots per inch, and why screen calibration needs effective PPI rather than printer DPI.
Leggi la guida Accuracy and troubleshootingEnglish
Reference Object Sizes for Screen Calibration
Use the correct credit card, A4 paper, US Letter, or custom reference size for screen calibration, with exact dimensions, fit advice, and error checks.
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