Online RulerMeasure a small object on a phone
Calibrate AR Ruler with a bank card, then place the object along the on-screen scale. Line up one end with zero, then look straight down as you move the marker to the other end. This works when the whole length fits on the lit screen and you can see both ends at once.
- The web ruler shows centimeters or fractional inches and saves the card calibration locally.
- Card calibration uses the edge as a physical reference. It takes no card data and needs no upload or sensor readings.
- The Play version offers optional ARCore on supported Android hardware and has a screen ruler to fall back on.
- Set the phone face up on a firm surface. Pick the orientation that gives the object enough room along the ruler.
- Open the card guide. Match it to the bank card edge shown on screen and save the calibration. An ISO ID-1 card has nominal dimensions of 85.60 mm by 53.98 mm.
- Choose centimeters or fractional inches. Rest the object on the screen if it can sit flat without scratching the glass.
- Line up the first end with zero. Look down over the far end and drag the marker to the tick it reaches.
- If you rotate the phone or change the browser zoom, compare the card with the guide again before taking another reading.
Leave room to read the marks
Place the object beside the scale so the tick marks stay visible. For a button or another round piece, line up one outer edge with zero and move the marker to the opposite edge across the widest part. Keep your view directly above the edge you are reading. Looking from the side can make a raised edge appear over a different tick.
Pick a method for longer objects
Use a physical ruler if the ends extend past the usable screen. If you use the Play version on Android hardware that supports ARCore, its optional camera mode can measure distance, a path made of connected segments, planar area, or an angle. The Play version also keeps up to five entries in local history and offers copy and share.
Read between marks
When the edge lands between two ticks, use the nearer tick if it is clearly closer. If the edge sits about halfway or is hard to see, keep the two marks as a range. A clearer reading may be possible if you turn the object so the edge you need lies closer to the scale. After turning it, line up the near edge with zero again.
Can I measure without a camera?
Yes. The screen ruler works by lining up the object with the marks. The Amazon and Galaxy versions provide the screen ruler only and have no camera mode or ads.
Can the case affect how I place the object?
A raised rim can hold the object above the glass. Use a clear part of the screen or take the case off if the rim gets in the way.
Can I switch units after calibration?
Yes. Choose centimeters or fractional inches and line up the near edge with zero before reading.