Online Ruler in Centimeters (CM)
Actual size metric centimeter ruler with 1mm minor subdivisions. Place your physical item on screen or drop guides to measure width and length.
Measurement Field
Place physical objects directly on screen, drag calipers, or tap rulers to drop guides.
How to Measure in Centimeters on Screen
1. Align the left or top edge of your physical object with the zero mark of the ruler.
2. Read the nearest whole centimeter number mark.
3. Count the fine tick marks between the whole numbers. Each small tick represents 1 millimeter (0.1 cm), while the medium tick represents 5 millimeters (0.5 cm).
Centimeter to Inches Quick Reference
| Centimeters (cm) | Decimal Inches (in) | Fractional Inches |
|---|---|---|
| 1 cm | 0.39" | approx. 3/8" |
| 2 cm | 0.79" | approx. 13/16" |
| 5 cm | 1.97" | approx. 2" |
| 10 cm | 3.94" | approx. 3 15/16" |
| 15 cm | 5.91" | approx. 5 7/8" |
| 20 cm | 7.87" | approx. 7 7/8" |
| 30 cm | 11.81" | approx. 11 13/16" |
Centimeter Ruler FAQ
Technical details on screen PPI, calibration accuracy, and physical scale.
How accurate is this online ruler in centimeters (cm)?
When calibrated using your screen dimensions or standard credit card, Real Size Ruler is 100% accurate down to the sub-millimeter level (0.1 cm). It scales CSS pixels to match the International System of Units (SI) definition of the centimeter.
How many millimeters are in one centimeter on this ruler?
There are exactly 10 millimeters (mm) in one centimeter (cm). On our CM ruler, the fine minor ticks represent 1 mm intervals, the medium ticks denote 5 mm (0.5 cm), and the tall labeled ticks mark whole centimeters.
How do I convert centimeters to inches?
1 centimeter is equal to approximately 0.3937 inches. Conversely, 1 inch equals exactly 2.54 centimeters. You can switch between cm and inches instantly by pressing "U" on your keyboard or clicking the unit buttons in the toolbar.