Is the iPhone Measure app accurate?

What Apple says

Apple’s own iPhone User Guide is the clearest answer. In its page on measuring dimensions, Apple says to use Measure from about 0.5 to 3 metres (2 to 10 feet) from what you’re measuring, and adds that the measurements are approximate (Apple).

So Measure, like any camera-based measuring app, gives you an estimate. It’s handy for “will this sofa fit?” and less so for “cut this shelf to length”.

What affects the result

Apple’s guide describes moving your iPhone slowly so Measure can find the space before you start (Apple). In practice, camera measurements are easier when:

• you stay within Apple’s suggested range, about 0.5 to 3 m (2 to 10 ft);
• you tap the real ends of what you’re measuring, looking straight at each point;
• the surface has enough visible detail for the camera to lock on to. The Measure App, for example, warns “Not enough detail here” when it can’t read a surface well.

Does LiDAR help?

Apple lists a LiDAR Scanner only on the Pro and Pro Max models, from iPhone 12 Pro onwards (Apple). Apple’s App Store listing for Measure says that on iPhone 12 Pro and later, guide lines make measuring easier and more accurate (App Store). On other iPhones, Measure works from the camera alone.

When to use a tape measure instead

Use a real tape measure, ruler or laser measure whenever a small error costs money or safety:

• cutting wood, worktops, glass or fabric;
• ordering made-to-measure blinds, curtains, doors or furniture;
• anything structural.

A phone measurement is a good first step: it tells you roughly what you’re dealing with before you go and find the tape.

How The Measure App handles this

The Measure App, which we make, also uses Apple’s ARKit. It labels readings as estimates when the camera can’t find a surface (“Estimated. No surface detected here.”), stops you placing points while it’s still finding its position, and tells you to move closer when you’re too far away. On iPhones with a LiDAR Scanner it also uses the depth information LiDAR provides. Its exported PDFs say the figures are approximate and should be checked before building work or expensive purchases.

That doesn’t make it exact, either. Like Apple’s app, it’s for planning and quick checks. We compare the two side by side in The Measure App vs Apple’s Measure app.