Why we built Actual Online Ruler
Actual Online Ruler was created around a small, familiar problem: you need to measure something, but a physical ruler is nowhere nearby. A screen is usually within reach, yet ordinary ruler images cannot account for the different sizes and pixel densities of modern displays.
Our goal is to make screen measurement straightforward and honest. The tool provides rulers in centimeters, millimeters, inches, and pixels, with calibration methods that adapt the scale to the display being used.
Designed for practical measurements
The ruler can be placed on any edge of the measuring area or shown on all four edges. Users can calibrate with a known device model, the diagonal size of a screen, or a standard credit card. Settings are stored locally so the preferred unit and calibration remain available on the next visit.
Actual Online Ruler is intended for quick measurements of small everyday objects such as stationery, craft materials, jewelry, screws, cards, and printed references. It is not a replacement for certified measuring equipment in engineering, medicine, construction, or other safety-critical work.
Our principles
- Keep the core ruler free and easy to access.
- Explain calibration limits clearly.
- Collect as little user information as possible.
- Build a fast, accessible experience for phones and computers.
- Improve the tool without making measurement more complicated.
Questions or suggestions?
We welcome reports about device presets, calibration behavior, accessibility, or ideas that would make the ruler more useful. Visit our Contact Us page to get in touch.