# OnScreenRuler

> Free online ruler for any screen

Source: https://rankcert.com/product/onscreenruler
Website: https://onscreenruler.com
Verification: Verified
Upvotes: 0
Launch week: 2026-10-12 · Updated: 2026-10-14

## Verified signals

- domain: verified (source: badge, verified 2026-10-14)

## About

OnScreenRuler turns any phone, tablet, laptop, or desktop screen into a measuring tool. It offers automatic device detection, manual device selection, screen size entry, or a bank‑card reference for calibration, so measurements in inches, centimeters, millimeters, or pixels are accurate. No app or account is required, and the tool is free to use.

## Questions

### Is OnScreenRuler accurate?

After proper calibration, measurements are typically within 1–2 % of the real size. For critical measurements, verify with a physical ruler or caliper.

### How do I calibrate the ruler?

Choose auto‑detect, select your device, enter screen size, or use a standard bank card. Adjust the guide until it matches the card width, then click Apply.

### Do I need an account or to download anything?

No. The tool runs in your browser, requires no download, and does not need an account. Calibration data is stored locally in your browser.

### Does it work on mobile devices?

Yes. OnScreenRuler works on phones, tablets, laptops, and desktop browsers with the same features.

Tags: online ruler, calibration, measurement, browser tool