Ruler in CM
Need a ruler in cm? This online ruler shows centimeters directly on your screen edge, with millimeter subdivisions for fine measurements. Calibrate once with the credit card method, and every ruler in cm reading stays accurate for good.
How to use the ruler in cm
Open the tool above and select cm as the unit. The top and left edges of your screen now display a ruler in cm starting from the corner. For a more precise calibration, press Calibrate and pick the credit card method — it takes ten seconds and makes the cm ruler in cm nearly pixel-perfect. You can show the cm ruler on any edge: top, bottom, left, or right.
Why calibrate before using a ruler in cm
A screen is not a physical object of fixed size, so a ruler in cm is only as good as your PPI calibration. Auto-detect recognizes over 100 devices instantly, the screen diagonal method works for any monitor, and credit card calibration gives the most accurate ruler in cm on unknown displays. After calibration, this online ruler is typically accurate within 0.5mm.
Centimeter reference chart for your screen
Use this quick reference to check whether your cm ruler in cm reads true: hold a real centimeter ruler against the screen and compare a few marks. If the numbers drift, recalibrate the online ruler and the cm scale will line up again.
| Centimeters | Millimeters | Inches |
|---|---|---|
| 1 cm | 10 mm | 0.394 in |
| 5 cm | 50 mm | 1.969 in |
| 10 cm | 100 mm | 3.937 in |
| 20 cm | 200 mm | 7.874 in |
| 30 cm | 300 mm | 11.811 in |
FAQ
How accurate is this ruler in cm?
Can I measure real objects with a ruler in cm?
Does the ruler in cm work on phones?
Open the online ruler and start measuring
Free, no install, calibrate once and measure forever.
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