Online Rulers — Actual Size
Real rulers on your screen, calibrated to your monitor's pixel density. Dual inch and centimeter scales. Drag to measure any span.
A full 12-inch ruler at actual size. Dual inch and centimeter scale, 1/16" precision. Drag to measure, calibrate with a credit card.
The standard school ruler length — exactly 300 mm. Centimeter and millimeter scale on top, inch scale on the bottom. Drag to measure.
A 500 mm scrollable millimeter ruler. Every individual mm marked. Perfect for precise metric work — mm primary, inch secondary.
A ruler spanning exactly 210 mm — the width of an A4 sheet. Lay a real A4 page against it to verify your screen calibration.
Print a 30 cm and 12 inch ruler at actual physical size. Set print scale to 100%, verify with the included credit card box.
A compact 6-inch ruler — great for smaller objects, half a foot. Inch and cm scales, same drag-to-measure and calibration features.
A 12-inch ruler with the inch scale highlighted. Perfect for US measurements — fractions of an inch marked to 1/16".
A 30 cm ruler with the centimeter and millimeter scale highlighted. Perfect for metric measurements — mm precision.
About These Rulers
Each ruler is drawn on your screen at actual physical size using your monitor's pixel density (PPI). At the default of 96 PPI, the rulers match most desktop monitors. For the highest accuracy, click "Calibrate" on any ruler page and use a physical credit card to set your screen's exact PPI.
All rulers include dual inch and centimeter scales. Drag on the ruler to measure any span — the measurement badge updates live. Your calibration is saved between visits.