Ever needed to get the dimensions of something but don't have a tape measure to hand? With a new app in iOS 12 you can use the augmented reality capabilities of your iPhone to get the measurements of any object you choose, here's how.

The Measure app can tell you the dimensions of rooms and objects in the real world by visualising them in augmented reality. While we've not found Measure to be super accurate, it is a fun, clever and exceptionally convenient way of finding approximate measurements - rather than something on which you would be wise to base the design of a house, for example.

How to measure things with the iPhone

Here's how you can use your iPhone to find out how big something is.

  1. Measure is a standalone app. The icon is a black square with white ruler notches and a yellow bar: tap this (you may need to swipe down and search for it) to open the app.Measure app iOS 12
  2. The first step is to orientate your iPhone to prepare it for measuring. When you first open the app you will see an animation indicating that you should move your iPhone around. Measure - orientate iPhone
  3. The next screen is a camera view showing whatever is in front of (well, technically behind) the iPhone. There's a circular target with a white dot in the centre, and a + button at the bottom - these are the key controls.Measure app iOS 12
  4. Now to measure. You'll notice, as you move the view over objects, that the target adjusts itself to the orientation of whatever it's pointing at. To measure the distance between two points, move your phone until the white dot is positioned over the first point and tap +, then move your phone so that a second white dot is positioned over another point on the thing you are measuring, and tap + again. The distance between the points will then appear onscreen. Measure with iPhone
  5. You can even measure an object that doesn't fit in the screen of your iPhone this way - tap on one side, move your phone right over to the other side, and then tap again. Then as you swipe your iPhone back across you will see the measurement, even if you can't see the whole thing you are measuring. Measure something big iPhone
  6. When you measure something the resulting measurement will remain on screen, even if you point the iPhone in a different direction and come back to the object you were measuring. You need to tap Clear at the top to start a new measurement.
  7. If you wanted to measure more than one side of something you can. Once you have two points selected you can then tap two entirely new points, or tap on another corner of the same object and then move the target close to one of the previous points and it will be easy to join it on. More than one side

How to measure a rectangle with the iPhone

If you've got an object that's a neat rectangle, Measure should be able to detect it automatically.

  1. Open the Measure app and hold your iPhone over, or in front of, the rectangular object.
  2. You should see the object automatically gain a yellow outline highlighted in orange. Once this happens you will see the option 'Add a rectangle'. Click the + to do this.
  3. You may not see the 'Add a rectangle' option, in that case you can just tap on the rectangle once it's highlighted and this will offer the dimensions. Measure a rectangle iPhone
  4. Either way, once the rectangle is recognised, you can tap it to see the dimensions. And in some cases the area squared will be shown as well.

(If it doesn't get highlighted, it's possible that the object's edges aren't clear enough, and you'll have to tap the corners manually. And at present Measure cannot auto-detect 3D cuboids, only 2D rectangles.)

How accurate is the Measure app

As we said in the introduction, we wouldn't use the Measure app if it was critical that we got the correct measurements for something, because if a few milimeters matters, then you might end up buying something too big for the gap you are trying to fill. In that case you should get out your trusty tape measure.

But if you just want to get a rough idea of how big something is, then Measure will give you an idea. Say you are in Ikea looking at a cupboard and want to know whether it will fit in the gap in your hall way, that's where Measure will give you an indication of whether or not to take the plunge and buy it.

As for that card we measured above - 17cm by 12cm, in real life it measures, 17.7cm by 12.5cm. So, no, it's not accurate, but what's a few mm between friends.

How to change the measurement units

Depending on where you are based you will see your measurements in either cm or inches.

If you want to switch between metric and imperial, go to Settings > Measure > Measure Units.

Measure units

Where is the Spirit Level app?

If you are a fan of using your iPhone for DIY you may be wondering where the Spirit level app has got to. 

Sensibly Apple has lumped it together with the Measure app, so, you can find it if you tap on the Level tab at the bottom of the Measure screen.

Measure works the same way as before - there's no AR component. It just feels like it would be useful in many of the same situations as Measure's other functions.

You place your iPhone on a surface - say a shelf you are putting up - and when it reads O you know it's not tilted.

Using Level app on iPhone