---
okf_version: "0.2"
title: Online Ruler Knowledge Bundle
description: Concepts and pages for online-ruler.net - the actual-size screen ruler, PPI calibration, printable ruler, and related measurement tools.
timestamp: 2026-09-05
---

# Online Ruler - Knowledge Bundle

Everything an AI agent needs to know about the Online Ruler site and tool.

## Concepts

- [Online Ruler Tool](online-ruler.md) - `reference` - the actual-size cm/mm/inch screen ruler and its features.
- [Calibration](calibration.md) - `howto` - why and how the ruler is calibrated to actual size.
- [Units and Conversions](units-and-conversions.md) - `reference` - cm/mm/inch facts and conversion rules.
- [Printable Ruler](printable-ruler.md) - `reference` - printing a 30 cm / 12 inch ruler at 100% scale.
- [PPI Calculator](ppi-calculator.md) - `reference` - computing a display's pixels per inch.

## Resources

- Sitemap: https://online-ruler.net/sitemap.xml
- Site index (llms.txt): https://online-ruler.net/llms.txt