Google Translate is already a hugely useful app for anyone who lives overseas or travels regularly, and it just got even smarter on mobile. A new update to the Android and iOS apps that is rolling out today introduces two very spiffy features: real-time voice and sign translation.

The app has already offered image-based translation, but now the magic occurs without any delay at all… and — best of all for regular travelers — it works offline.

The visual translation feature is activated when you select the phone camera option inside the app. You then simply point the camera at the sign that you want translated — ensuring that it is captured fully — and the app will translate it.

Real-time voice translation is equally incredible, and can act as an intermediary for two people holding a conversation using different languages.

You tap the in-app mic once and starting talking in the foreign tongue first. Then — once the first language has been recognized — tap the mic again and both people can begin talking. The app pulls in text-based translations of both sides of the conversation in real-time, helping overcome the language barrier.

Voice translation has been a feature on Google Translate for Android for some time, but now it is coming to iOS and will also be “faster and more natural” on Android, Google says.

The sole caveat is that these instant translation features are somewhat limited at first. They only work for English to and from French, German, Italian, Portuguese, Russian and Spanish, but Google said it has plans to expand support with time.

Interestingly, the company also threw out some new stats about the popularity of Translate. It claimed that 500 million people use the service in some form each month, with more than one billion translations made per day.

Those figures are quite incredible and — with two hugely useful new features now up and running on both iOS and Android — Google Translate is likely to grow into even more of a monster hit.

Update: As some readers have pointed out, this impressive technology is powered by World Lens, a startup that Google bought last year. Credit where it is due.