Nearly one-in-three Optus post-paid customers exceeded their monthly data limit and were ‘tiered up’ during the first few months this year, indicating a success for the telco’s restructuring of excess data fees, but suggesting more education is needed for Aussie smartphone users about the potential cost of their data usage habits.

According to Optus' latest financial results report, 31-percent of post-paid customers on My Plans were automatically bumped up to a higher data tier between January and March of 2014 alone. This extra data costs Optus customers $10 per 1GB, in addition to the data inclusions in their mobile plan.

Automatic data increases are a unique feature of Optus post-paid plans. If the same customers exceeded their data in a similar way on a competitor’s network they would be charged for each megabyte used. Telstra is cheapest at 3c per MB, Virgin next along at 5.2c per MB, while Vodafone charges a higher 10c per MB rate for excess data.

Optus now has 862,000 customers on its post-paid My Plans, and a total of 2.15-million 4G handsets registered on its network.

How much is enough?

If you've been following along with a calculator, Optus is reporting that 267,000 of its customers have blown their data budgets over just 3-months; or in other words -- way too many people have underestimated how much data they need.

You could argue that Optus customers are more likely to exceed data limits because of the financial safety net the telco’s tiering system offers, but it is equally likely that Australians are using more costly data on their phones without being aware of it at the time.

We recently put together a comprehensive guide to how much data is used by a variety of common online services, but here is a quick snapshot of common data hogging apps.

Facebook = 1- 2MB per minute

Web browsing = 1- 4MB per full-size webpage loaded

YouTube = up to 6MB per minute (depending on quality)

Music streaming = 1- 2MB per minute

On top of these services, people also download apps, which vary greatly in size — from a couple of megabytes up to 40- 50MB for some newer games.

When you remember that 1GB is 1048MB you can start to see how quickly you can get through this data during several weekday commutes to and from school or the office.