Precise Online Ruler.Open ruler A ruler when you need one
Precise Online Ruler helps you measure small objects and on-screen distances without installing an app or creating an account. Open the ruler, choose your units, and set the scale for your screen.
It is built for everyday tasks: checking a craft detail, estimating the size of a small part, or comparing dimensions while you work at your desk.
Make your screen work for you
Use inches, centimeters, millimeters, or CSS pixels. Place rulers along the edges you need, or drag a selection to read its width, height, diagonal, and area. Calibration options include a known physical reference, your device model, and your screen diagonal.
Accuracy starts with calibration
Screens have different pixel densities, and browser zoom can change the displayed scale. For physical measurements, calibrate against an object with a known size and check the result. Recalibrate whenever you change your display or zoom.
The ruler is intended for convenient everyday use. Use a suitable physical measuring instrument whenever precision or safety matters.
Built to keep things simple
The measurement tool runs in your browser. Calibration and preferences are saved in local browser storage when available. Your five most recent drag measurements stay in memory and clear when you reload. Read our Privacy Policy for more detail.
Help us improve
Found an issue or have an idea? Visit our Contact Us page. Details about your device, browser, and calibration method help us understand measurement problems.