Online RulerUse a ruler on a laptop screen
Calibrate AR Ruler on the laptop display with a bank card. Hold the item lightly beside the ruler with its first edge at zero. At eye level, move the marker to the far edge and read the distance. This setup suits small items you can hold steady without pressing them against the display.
- The website and desktop or extension ruler show centimeters or fractional inches.
- Calibration uses the physical edge of a bank card and saves the scale locally.
- Browser zoom and display changes can invalidate the scale when detected. Compare the card with the guide again after a change.
- Put the laptop on a steady surface. Set the lid angle and browser zoom where you want them before calibrating.
- Hold a bank card beside the calibration guide and match the indicated edge to both ends. an iso id-1 card has a standard long side length of 85.60 mm.
- Choose a unit and line up the near edge with zero without leaning on the lid.
- Hold the item close to the scale, with one end at zero and the length parallel to the ruler. Read the tick beside the far end.
- If the lid shifts or your hand slips, set the item back at zero and take the reading again.
Line up your view
Tilt the lid so you can look squarely at the part of the screen you are using. Hold the item close enough to see which tick meets its edge. If the item sits away from the display, looking from above or from the side can shift the apparent reading. Move your head to face the far edge directly while keeping the starting end at zero.
Pick a clear spot
Keep the item over the usable display area. The bezel can hold a flat item away from the ruler or hide the edge you need. For a rigid piece, line up the same side from one end to the other. For something soft or curved that changes shape while you hold it up, put it on a table and use a ruler there.
Check a printed scale
For a piece you want to lay down, print the AR Ruler page with the 15 cm and 6 in scales. Each scale is sized independently in physical print units. Select actual size in the print dialog. Compare the 10 cm test line with a physical ruler. If it comes out short or long, correct the print settings and check a fresh copy before measuring.
Does changing the lid angle change the scale?
Tilting the lid changes your viewing angle. Face the screen squarely and realign the item before reading.
Can I use my laptop's saved scale on an external display?
Check the card guide on the external display first. Redo the calibration there if the guide and card differ.
How do I convert an inch reading to millimeters?
Multiply the inch reading by 25.4. One inch equals 25.4 mm. Keep the result to the precision you could read on the scale.