TrueRuler: Pocket Ruler

A screen ruler with movable guides, cm and inch scales, and manual calibration. Measure offline and keep calibration settings on your device.

TrueRuler is a screen ruler with manual calibration, designed for checking and comparing the length of small objects that fit within your screen.

Move the green start guide and red end guide to see the distance between them. Switch between centimeters and inches, or change the ruler direction to suit the object you are measuring.

Features • Centimeter scale with 1 mm divisions. • Inch scale with 1/16-inch divisions. • Two movable guides with a direct length readout. • Lock the guides to avoid accidental movement, or reset their positions. • Expand the ruler to full screen while keeping measurement controls within reach. • Calibrate against a reference of known length. • Save horizontal and vertical calibration separately.

Measuring requires no account or internet connection. Calibration settings stay on your device.

Before measuring Check the scale against a physical ruler before first use, and calibrate each direction when needed. Start from the zero mark shown on the screen. Actual accuracy depends on the device, display settings, and calibration. Decimal places in the readout do not indicate certified measurement accuracy.

For iPhone and iPad. Supports device rotation and horizontal or vertical ruler layouts.