Online Ruler
Free online ruler in cm and inches on your screen. The scale follows your system display scaling, so you can measure small objects directly in your browser.
Is the ruler really accurate?
The scale follows your system display scaling . On most setups this is close to real size, though small deviations between displays are normal. The estimate assumes a 15.6-inch screen diagonal.
The ticks don't match my physical ruler — why?
Most often the browser zoom is not 100%. Reset the zoom to 100% and reload the page; the scale is derived from your system display scaling, not from a per-monitor calibration.
Can I switch between centimeters and inches?
Yes, use the cm / inch buttons above the ruler. The scale, tick marks and numbers switch instantly between metric and imperial units.
Why do I need fullscreen mode?
Fullscreen maximizes the ruler area so longer objects fit against the scale, and it hides browser interface elements that could overlap your measuring.
Does the ruler work on phones?
Yes. Place small objects directly on the screen and read their length. Phone displays are usually well suited for measuring items under 10 cm.
Is any data sent anywhere?
No. The ruler is drawn entirely in your browser with canvas; nothing is uploaded.
What can I measure with it?
Small flat items: coins, keys, screws, cables, jewelry, paper sizes. Place the object against the screen edge next to the scale and read the length.
How to Use Online Ruler
This online ruler draws a cm and inch scale in your browser following your system's display scaling, so small flat objects can be measured against the screen. Everything is drawn locally; nothing is uploaded.
- Switch between cm and inch with the buttons above the ruler.
- Place a small flat object against the screen edge next to the scale and read its length from the ticks.
- For the truest scale, keep the browser zoom at 100% — the scale follows your system display scaling.
- Press "Fullscreen" to maximize the scale for longer objects.
Pixel density differs slightly between displays, so for precision-critical measurements compare the scale with a real ruler once.
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