๐Ÿ“œ Terms of Service

Terms and Conditions

Last updated: 2026

Please read these Terms and Conditions ("Terms") carefully before using onlinerulerai.com ("the Service"). By accessing or using the Service, you agree to be bound by these Terms.

1. Use of the Service

OnlineRulerAI is provided free of charge for personal and professional use. You may use the Service to measure objects using your screen as a ruler. No registration or payment is required.

You agree not to:

  • Use the Service for any unlawful purpose
  • Attempt to reverse-engineer, scrape, or copy the Service for redistribution without permission
  • Interfere with or disrupt the servers or networks that host the Service

2. Accuracy Disclaimer

OnlineRulerAI is designed to provide accurate measurements when properly calibrated. However, accuracy depends on:

  • Correct calibration by the user
  • The physical characteristics of your specific screen
  • Browser zoom level (measurements assume 100% zoom)
  • Screen scaling settings in your operating system

โš ๏ธ Precision Warning

Do not rely on OnlineRulerAI for safety-critical measurements โ€” such as medical, engineering, or construction applications where measurement errors could cause harm. For precision work, use calibrated physical instruments.

3. Intellectual Property

The design, code, text, and visual assets of OnlineRulerAI are owned by us and protected by copyright law. You may not reproduce or redistribute them without prior written permission. The measurement functionality of the Service โ€” using a screen as a ruler โ€” is not claimed as proprietary; only our specific implementation is protected.

4. Disclaimer of Warranties

The Service is provided "as is" and "as available" without warranties of any kind, either express or implied. We do not warrant that the Service will be uninterrupted, error-free, or completely accurate for all devices and screens.

5. Limitation of Liability

To the fullest extent permitted by law, we shall not be liable for any indirect, incidental, special, consequential, or punitive damages arising out of your use of, or inability to use, the Service โ€” even if we have been advised of the possibility of such damages.

6. Third-Party Links

The Service may contain links to third-party websites. These links are provided for convenience only. We have no control over third-party content and accept no responsibility for it.

7. Changes to These Terms

We reserve the right to modify these Terms at any time. The "Last updated" date at the top of this page will reflect the most recent revision. Your continued use of the Service after changes are posted constitutes your acceptance of the revised Terms.

8. Contact

Questions about these Terms? 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 โ€” 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.

โ“ 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 '1โ€ณ' 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.