Actual Size Measurement
85.6mm. Place your card on the screen and adjust the slider until the markings match the card edges.Centimeter to Inch Conversion Table
| Centimeters (cm) | Inches (in) | Millimeters (mm) | Pixels (px, 96 DPI) |
|---|
How to Use
π Using the Online Ruler
- Measure objects: Place the object on your screen and read the size from the ruler markings
- Place guide line: Click anywhere on the ruler to place a measurement line β drag to move it
- Switch orientation: Use the "Horizontal/Vertical" buttons to change ruler direction
- Switch units: Select "Both" to show cm and inch simultaneously, or pick one
π§ Calibrating for Accuracy
- Auto detect: Click "Auto Detect" to use the browser's DPI estimate (may not be precise)
- Credit card calibration: Place a standard credit card (85.6mm wide) on your screen, then drag the DPI slider until the 85.6mm mark aligns with the card
- Manual entry: If you know your screen DPI, drag the slider directly
π Inch Fractional Markings
The inch scale includes four precision levels: 1/2 (longest tick), 1/4, 1/8, and 1/16 (shortest tick). For example, 3Β½ inches is marked as the long tick between 3 and 4 on the ruler.
Frequently Asked Questions
Is the online ruler accurate?
Accuracy depends on screen DPI calibration. The default uses the browser's DPI estimate, which may have some deviation. After calibrating with a credit card, the error is typically within 1mm. Since screen DPI varies by device, we recommend calibrating before first use.
How many inches is 1 centimeter?
1 centimeter = 0.3937 inches, and 1 inch = 2.54 centimeters. This ruler shows both scales simultaneously for easy conversion.
Can I use it on my phone?
Yes. The tool works in mobile browsers with touch support. Tap or drag to place the measurement line. We recommend calibrating first for accurate results.
Why doesn't the full ruler fit on my screen?
The ruler width is limited by your screen size. To measure larger objects, try zooming out in your browser (Ctrl/Cmd + -).