Apple’s Measure App and Accuracy

One of the more interesting apps in iOS 12, which Apple released this week, is Measure. It uses augmented reality (AR) to calculate the length, width, and area of items. This is a complex process, which involves having the iPhone or iPad calculate the distance between its camera and the object you are measuring in order to determine the object’s dimensions.

The problem is that it is not very accurate.

I tried measure a number of objects, and two things were apparent. The first is that Measure is not very accurate, and the second is that the same object measured twice can return different dimensions.

Here are some examples:

Measure1

The inside of the frame measures 78 cm x 101cm; the Measure app is off by about 20%.

Measure2

The stool above measures about 38cm x 53cm. The Measure app isn’t that far off, and this would be an acceptable measurement if I were, say, sizing up furniture for my living room, where tolerances don’t need to be precise.

But what is worrisome is the fact that when I’ve measured the same items multiple times, the results differ. Here are two measurements of one of my shakuhachis.

Measure3

Measure4

Ignore Rosalind the Cat; she wanted to see what was going on, but I had completed the measurement before she started checking it out. I took both of these measurements from the same position, with the iPhone at the same height. The shakuhachi is 55cm long; while one might allow for a bit of tolerance because the measure points are not exactly at the ends of the instrument, they do both end up at about the same position on the instrument.

I thought I’d give it another chance today; it’s sunny, and yesterday was a bit overcast. This time it says 57cm.

Measure5

And here’s one last example; I got as close as I could, and it even says on the cover that it’s 21cm x 29.7cm…

IMG 8118

In a Twitter conversation yesterday, some people said they found it very accurate, others not at all (one showed a 38″ MacBook Pro they had measured). I don’t know if this app is better suited for certain types of measurements, such as full rooms and the height of walls, but my tests show that its results are essentially estimates.

The Measure app is a good party toy, but little more, in its current state.

Note that these measures were taken with an iPhone 8+; I’m not sure if it uses the dual cameras, but if so, the parallax of the dual cameras should make it more accurate than a single camera.

8 thoughts on “Apple’s Measure App and Accuracy

  1. I haven’t tried it yet (iPhone 8 here) but this doesn’t sound encouraging. When I need a measurement I usually need one that’s pretty accurate. I’ll probably test it measuring a box as I need W/L/H when I ship via UPS and those probably don’t need to be exact.

    • But those often need to be below a certain threshold, so you do need some level of accuracy. If you’re well below the threshold, then it’s fine, but if it’s close, I’d want to get out a measuring tape to be safe.

  2. I removed this app pretty much as soon as I spotted it after updating my iPad, along with Stocks. I then removed Music (which I don’t need or use on my iPad).

  3. I found that they seemed to focus on making it better with Imperial measurements, as it will show fractional inches that are (slightly) more accurate than rounding off to the nearest Centimeter.
    For example, an 8 1/2 x 11 paper measured ok, but gave inconsistent measurement in Metric. I didn’t continue with objects that had 1/4″ or 1/8″ in it’s measurements.
    Perhaps not allowing it to measure to the nearest Millimeter is telling of it’s accuracy. Maybe it will work better with the XS cameras?

    • I have the 8+ with dual cameras, as I said in the article. So I can’t see that a newer camera would make it any more accurate.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.