ScreenRuler - Measure Length

Turn your iPhone into a precise ruler — no physical ruler needed. ScreenRuler uses your device's actual pixel density (PPI) to display accurate centimeter and inch graduations directly on screen. Place any object alongside the ruler and drag two handles to measure it instantly. HOW TO MEASURE 1. Place the object next to the left edge of the screen 2. Drag the top and bottom handles to align with the object's edges 3. Read the live measurement displayed between the handles FEATURES • Accurate ruler based on your iPhone's true screen PPI • cm mode: 1 mm graduations, labeled every 1 cm • inch mode: 1/8 inch subdivisions, labeled every 1 inch • Two drag handles for precise range selection • Live measurement display — updates as you drag • Switch between cm and inch instantly • DPI calibration using a standard credit card (short edge 5.4 cm) for extra precision • Haptic feedback at every 1 cm / 1 inch boundary • Dark and light theme • Works offline — no internet required • Collapsible control panel — stays out of the way CALIBRATION Every iPhone screen has a slightly different physical size. Use the built-in DPI calibration with a standard credit card to fine-tune accuracy to your exact device. Perfect for quick measurements when you don't have a ruler on hand.