Downloads on mobile devices in Australia doubled over the last 12 months, figures show, as more people embraced smartphones and 4G networks.

Australians with mobiles or tablets collectively downloaded 20,000 terabytes of data in the three months to June, up from 10,000 in the same period last year, according to figures released on Tuesday by the Australian Bureau of Statistics (ABS).

The figures suggest the average mobile subscriber downloads about 300MB of data per month, the ABS said - the equivalent of about 100 songs.

"Download volumes for mobile handsets have really seen explosive growth," said ABS assistant director Lesley Martin.

The increase has partially been driven by growth in the number of people using smartphones and tablets, figures show.

There were 19.6 million mobile subscribers by June - an increase of three million on June 2012.

Foad Fadaghi, a senior analyst at research firm Telsyte, said the increase was also fuelled by the introduction of 4G mobile networks, which offer faster speeds and encourage more downloads than 3G networks.

"People have started using mobile apps for many of the things they used to do on computers," he told AAP.

For example, the use of social media apps such as Facebook, Twitter and Instagram has "exploded" in the past year, he said.

Music streaming services such as Pandora and Spotify were also boosting the amount of data people use, he added.

The results come as analyst firm IDC released figures showing mobile phone shipments are down 20 per cent on 2012.

The drop has been driven mainly by a 45 per cent drop in shipments of feature phones (old-style mobile phones), but IDC said there has also been a "slight decline" in smartphone shipments.