KLM Royal Dutch Airlines has added an augmented reality bag sizer tool to its app to help passengers figure out if their carry-on bags comply with the airline’s rules.

The augmented reality bag check tool shows a virtual KLM suitcase that is the size of a carry-on bag that fits the dimensions of the bags KLM allows on board.

When the user points their phone at their own carry-on bag, the augmented reality tool can measure the bag against the sample bag.

Here’s a video that shows how the tool works.

While it seems that many passengers ignore most airlines’ rules about the dimensions of carry-on bags allowed,  the augmented reality tool seems like a great way for resposible travelres to comply with the rules.

This also seems like a good way to avoid arguments at the gate when KLM gate staffers are being sticklers about enforcing the rules.

If it works well, this is a tool every airline could add to their app.

Passengers could use it to measure their bag before they leave home. In the boarding area, gate agents who feel a bag is oversized could just aim their version of the app at a bag. If there’s debate, both passenger and gate agent could take a screen shot of the results.

Now there just needs to be a way to weigh bags with an app!

KLM’s app offers some other augmented reality features as well, including a 360-degree display of a Dreamliner aircraft and, in the KLM Houses App, a look at Anthony Fokker’s House 98.