Online RulerWhen a browser ruler can stand in for Apple’s Measure app
Use a calibrated browser ruler for a short, flat object that fits along the visible scale on your screen. A bank card gives you a physical reference for setting the scale. Once the scale is set, you can read the length of a small label or a strip of paper without using a camera.
- Apple’s Measure app uses the iPhone camera to estimate physical dimensions. It can measure between two points and detect rectangular objects. Apple describes its readings as approximate.
- The browser ruler uses a physical bank card of the standard ID-1 size as a local scale reference. Hold the card against the display and match its edges to the calibration guide.
- The browser ruler’s marker shows the distance from zero in centimeters or fractional inches. The full object or span you want to measure must fit within the visible scale.
- Open the ruler in the browser window you plan to use. Pick centimeters or inches and leave the browser zoom as it is after calibration.
- Hold a standard ID-1 bank card flat against the screen. Match its long edge to the calibration guide so the guide lines up with both ends of the card.
- Place a small paper label along the ruler. Line up one end with the zero mark and keep the label parallel to the scale.
- Move the marker to the label’s other end. Look straight at the screen and read the distance from zero in your chosen unit.
Check that the whole span fits
Both ends need to be visible at the same time, with one end at zero. You can measure the width of a label even if its length extends past the scale. Turn the label so the edge you want to measure runs along the ruler.
Use the camera for an object that stays in place
Use Apple’s Measure app for an estimate when you need to measure between points on a fixed object, such as the edges of a mounted frame. The app can also detect rectangular objects when you point the iPhone camera at them.
Use a physical ruler when fit matters
Reach for a physical ruler when you need to mark a cut or check whether a piece will fit in a slot. You can put its graduations directly beside the edge and mark the material at the measurement.
Can I calibrate with a picture of a bank card?
Use a physical standard ID-1 card. A picture can appear at any size on the display.
What if I change the browser zoom?
Match the guide to your card again before measuring. Zoom can change the physical spacing of the marks on the screen.
Where do I start the measurement?
Start at the printed zero mark. There may be a gap between zero and the edge of the display.