🔒 Security & Confidentiality

Privacy Policy

Last updated: 2026

Overview

OnlineRulerAI ("we", "our", "the service") is committed to protecting your privacy. This policy explains what information we collect, how we use it, and your rights. The short version: we collect almost nothing and we do not sell or share your data.

1. Information We Collect

We do not require you to create an account or provide any personal information to use OnlineRulerAI.

The ruler tool runs entirely in your browser. Any calibration data (your screen PPI, chosen calibration method, theme preference) is stored only in your browser's localStorage and never transmitted to our servers.

We may collect the following non-personal, aggregated data through standard server logs and analytics:

  • Pages visited and approximate session duration
  • Browser type and operating system (aggregated)
  • Referring website or search engine
  • Country-level geographic region (not precise location)

2. Cookies

OnlineRulerAI does not use advertising cookies or third-party tracking cookies. We use localStorage (not cookies) to remember your calibration and theme preference between visits. This data never leaves your device.

You can clear this data at any time by clearing your browser's site data for onlinerulerai.com.

3. Third-Party Services

We use Google Fonts to load typefaces. When your browser downloads these fonts, Google may log your IP address as part of standard font delivery. Please refer to Google's Privacy Policy for details.

We do not embed social media widgets, advertising networks, or any other third-party trackers.

4. Data Retention

We do not store personal data on our servers. Server access logs, if retained, are kept for no longer than 90 days and are used solely to diagnose technical issues.

5. Children's Privacy

OnlineRulerAI is a general-purpose tool suitable for all ages. We do not knowingly collect any personal information from children under 13. Since we collect no personal information from any user, this service complies with COPPA by design.

6. Your Rights

Because we do not collect identifiable personal data, there is typically nothing for us to retrieve, correct, or delete on your behalf. If you have concerns, please contact us and we will respond promptly.

If you are located in the European Economic Area, you have the right to access, rectify, or erase any personal data we hold, and to lodge a complaint with your local supervisory authority.

7. Changes to This Policy

We may update this Privacy Policy from time to time. The "Last updated" date at the top of this page reflects the most recent revision. Continued use of the service after changes are posted constitutes acceptance of the revised policy.

8. Contact

Questions about this Privacy Policy? Contact us here.

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Auto Screen Calibration

OnlineRulerAI auto-detects your screen PPI database (250+ devices) to display 100% 1:1 real-world dimensions instantly.

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Credit Card & Coin Fit

Match any standard credit card (85.60 mm), bank card, or coin against your display for pinpoint physical accuracy.

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Visual Caliper & Guidelines

Drop reference guidelines, track cursor crosshairs, or drag rulers across screen edges in inches, cm, mm, and px.

Free Online Ruler — Measure in Inches, cm & mm at Actual Size

Free online ruler calibrated to actual size in inches, cm, and mm without downloads. Features auto screen detection, credit card calibration, protractor, and visual calipers.

Calibrate for 100% Physical Accuracy

Click Calibrate to auto-detect your screen or match a physical credit card, banknote, or monitor diagonal.

  • 1. Device Database: Auto-detect screen PPI database (250+ devices).
  • 2. Screen Diagonal: Calculate exact PPI from monitor diagonal in inches.
  • 3. Credit Card: Match physical credit card (85.60 mm) to on-screen slider.
  • 4. Banknote & Object: Compare physical banknote or coin against screen.

Select Your Measurement Unit

Switch between Centimeters (cm), Millimeters (mm), Inches (inch), Pixels (px), Points (pt), Picas, Feet, and Yards.

Place & Measure Objects

Place objects along screen edge rulers, drag visual caliper, or click Guidelines/Crosshair to measure in real time.

❓ Frequently Asked Questions (FAQ)

Click any question below to expand the detailed answer.

Q1. Can I use my phone as a ruler?
Yes! OnlineRulerAI turns any smartphone (iPhone, Android, Samsung, Pixel) into a 1:1 actual size digital ruler. You can calibrate your mobile display using a standard credit card (85.60 mm) or auto-detect your device model to measure physical objects directly on your screen.
Q2. Is there a ruler online?
Yes, OnlineRulerAI provides a free online ruler calibrated to actual real-world physical dimensions. It displays 12 inch, 30 cm, and millimeter scale lines on your monitor, tablet, or mobile phone screen without downloading any app.
Q3. How to identify 1 inch?
One inch equals exactly 2.54 centimeters or 25.4 millimeters. On an actual size online ruler, 1 inch is demarcated by the longest tick mark labeled with a '1″' symbol.
Q4. How to measure cm online?
Select the 'cm' unit button on OnlineRulerAI. Place your physical object flat against your screen aligned with the zero line (0 cm), and read the corresponding major mark.
Q5. Can a smartphone measure?
Yes, via camera AR apps or directly on screen using OnlineRulerAI browser tools for small items up to 15 cm with millimeter precision.
Q6. Can I use my camera as a ruler?
Yes! Camera ruler applications use AR camera alignment to measure room dimensions, furniture, and larger physical items in real-time.
Q7. Can we measure online?
Absolutely. You can measure physical items directly on your computer or mobile screen using OnlineRulerAI's free web tools.
Q8. How to read a ruler online?
Align one end of your object with the '0' mark. In cm mode: numbered tick marks are centimeters; smallest ticks are millimeters. In inch mode: numbered ticks are full inches.
Q9. How to view or add a ruler in Word Online?
In Microsoft Word Online, click on the 'View' tab in the top ribbon and check the 'Ruler' box.
Q10. How to show a ruler in PowerPoint Online?
In Microsoft PowerPoint Online, navigate to the 'View' tab and check the 'Ruler' box.
Q11. How to use an online ruler?
Open OnlineRulerAI in your browser, click 'Calibrate' to adjust your screen PPI with a credit card or device model, and lay your object flat on the screen to measure.