Arguably the biggest question for anyone looking for an NBN plan in Australia, the question of how much data you need is similar to the data question when shopping for a mobile phone plan. However, there's one obvious difference: where your phone plan's data is based on how much you expect to consume when you're out and about, your NBN plan's data is about the data you'll consume at home.
When you're at home, there's a good chance your internet usage is very different compared to when you're out and about on your phone. There's the regular day to day email and web surfing, social media, and then all the entertainment in your life.
Video services such as Netflix, Stan, Amazon Prime Video, Disney+, and catch-up TV services such as ABC iView and SBS all rely on an internet connection, and consume data based on how much you watch and the resolution you watch it at. A Netflix viewing can range between 1GB per hour in standard definition to up to 7GB per hour in 4K, and that's just on one screen. If there are more people in your household watching or streaming entertainment at the same time, the downloads can rack up.
Music services can make a smaller dent, but over time, it can amount to serious downloads, and not just for your phone. If you stream music to a Sonos, an Amazon Echo, the Apple HomePod Mini, or a Google Nest speaker, the music being streamed to your device chews through downloads as well, ranging from between 40MB per hour to 400MB if you stream in a particularly high audio quality setting.
And if there are any gamers in your home, they could be burning their way through a download quota in serious ways. While every experience is different and individual PC and console game titles handle downloads in unique ways, you could see as much as 500MB per hour downloaded simply by gaming online, possibly more.
The moment you start looking at what you use and download, the data can seriously add up, and it gets more complex depending on how many people there are in your home.
It's worth remembering that uploads count as well, so it's not just about what you receive, but also what you end up sending. You can receive a 1MB email, but if you send out a 20MB PDF attachment as a response, you've just taken 21MB of data out of your supply. Uploads count the same as downloads.
Ultimately, you'll need to factor all of this into your cost, and work out how much data you need accordingly. Consider estimating over what you need, or looking for an unlimited plan if you're concerned about overage.