Can a computer accurately guess your age based on a single photograph?

At the Build developer conference in San Francisco, Microsoft showed off a website that claimed to be able to do just that.

And that’s where the fun started.

How-old.net was born from a test of Microsoft's face recognition API.

This is how it works: you upload a photograph of yourself (or anyone else) to the site, and sit back and wait while it analyses the image.

From that image, it uses Microsoft’s facial recognition technology to pick out the faces, and then determines the sex of the subject based on algorithms.

How accurate is it?

It depends on the photo.

A few tests show that it generally picked up the subject’s sex correctly, but the age varied widely.

Users reported that close up photos yield different results to photographs taken further away, for example, and facial hair can also throw out the results.

A few Irishtimes.com tests ranged from the more flattering - roughly 10 years younger than the actual age - to downright insulting.

Of course, Microsoft makes it clear that it’s still a work in progress.

Each photo that’s analysed comes with the disclaimer that they’re still improving the feature.

Try it at your own risk.