The short answer
How to check your data and size your plan to it
Most people in Australia pay for more mobile data than they ever use, because a "just in case" buffer feels safe. Here is the part the ads leave out. The single most valuable five-minute job you can do is check how much data you actually used over the last three months, then size your plan to that plus a small buffer. Your data is sitting right there in your carrier app, or in your phone settings, and a handful of activities (video streaming and hotspotting) do almost all the eating. Knowing your real number, and controlling those few heavy items, is how you stop overpaying for gigabytes that expire unused at the end of every month.
Here is the core takeaway in one line: open your carrier app or your phone settings, read what you actually used over the last three months, then buy a plan that matches that figure plus a small buffer of around 20 per cent. The common assumption is that a bigger data plan is safer. It rarely is, because unused data expires at the end of the month, so the "just in case" gigabytes are pure margin for the carrier. The good news is that the fix takes five minutes and costs nothing: once you know your real number, you can shop it across brands and usually find the same allowance for less.
Reframe the assumption: a data plan is not insurance you should over-buy. Unused gigabytes do not roll over on most plans, they simply vanish, so a large buffer is money spent on nothing. The right size is your real three-month average plus a little headroom, not the biggest number a carrier will happily sell you.
The blind spot
Why most data-plan advice sends you the wrong way
Most articles about mobile data in Australia repeat the same three mistakes, and each one nudges readers into paying for the wrong thing.
First, they tell you to guess. They offer vague bands ("light users need this, heavy users need that") instead of the one accurate step: read your real usage in your carrier app or phone settings. Your own number beats any generic table.
Second, they treat a buffer as safety. They recommend rounding up to a much bigger plan "just in case", glossing over the fact that unused data expires. A 20 per cent buffer covers a busy month; doubling your plan just costs more.
Third, they treat the brand as the network. They compare logos rather than which of the three networks each brand rides. That misses the cheapest way to get the same data on a major network: through a smaller reseller on the same towers.
How to read your usage and act on it
Expert analysis: where to check, what eats data, and how to right-size
Where to check, and why three months beats one
You have three reliable places to look. Your carrier app (Telstra, Optus, or whichever brand you are with) shows usage for the current billing period and usually past ones, and it is the most accurate for your plan cycle. On an iPhone, open Settings then Mobile and scroll to see usage by app. On Android, open Settings then Network and internet then Data usage. Whichever you use, look at the last three months, not just last month: a holiday, a big download or a stint away from home Wi-Fi can spike a single month and mislead you. Three months smooths out the one-offs and reveals your genuine baseline.
What actually eats your data
A short list does almost all the damage. Video streaming is the runaway leader, at about 1 GB an hour for HD and several times that for 4K. Hotspotting a laptop or tablet is next, because tethering pulls full desktop pages, updates and cloud syncs you would not trigger on the phone. Large downloads and automatic app updates also add up. By contrast, browsing, email, messaging and even music streaming are light: a heavy music listener rarely tops a few gigabytes a month. Knowing which bucket your usage falls into tells you what to control.
Right-size to your real average plus a small buffer
Once you have your three-month average, the plan size almost picks itself. Add a buffer of around 20 per cent for a busier-than-usual month and stop there. Resist the "just in case" jump to a much larger plan: the extra gigabytes expire unused and are pure margin for the carrier. If you do occasionally run over, check what your plan does at the cap, as many now slow your speed rather than charge excess fees, which makes a modest buffer perfectly safe.
Use Wi-Fi and data-saver to shrink the heavy items
Because a few activities dominate, a couple of small habits cut your needs fast. Stream video on home or work Wi-Fi where you can, since that is where most heavy viewing happens anyway. Turn on the data-saver mode in your streaming apps and your phone settings to cap video quality on mobile. Download playlists and shows over Wi-Fi for offline use. Do those few things and your real mobile data number can drop enough to move you down a plan tier.
Interactive explainer
Estimate the data you need
Set your weekly mobile video hours and tick your other habits. The tool estimates your monthly data and suggests a plan size with a small buffer.
Hours of mobile video per week:
Your other habits
Your estimated data per month
GB
Illustrative only. Assumes roughly 1 GB per hour of HD video, about 1 GB per 15 hours of music, a small browsing baseline, and around 10 GB a month if you hotspot often. Your real figure is the one in your carrier app. Source: typical streaming and carrier guidance.
The same numbers, in plain text
How much data each activity really uses
A rough guide to the data each task eats. Video is the one that adds up fast; everything else is light by comparison.
| What you do | Data used | What it means |
|---|---|---|
| One hour of HD video streaming | ~1 GB | The single biggest driver of mobile data. Two hours a day adds up to roughly 60 GB a month on its own. |
| Fifteen hours of music streaming | ~1 GB | Audio is light. A heavy music listener rarely tops a few gigabytes a month from streaming alone. |
| Browsing, email and social (per hour) | ~0.1 GB | Text and images are tiny next to video. A whole month of browsing rarely passes a few gigabytes. |
| Hotspotting a laptop (per hour, mixed use) | ~0.5 GB | Tethering pulls full desktop pages and updates, so it burns data faster than the same task on the phone. |
What this means in real life
How Australians overpay for data they never use
The mechanics above are not abstract. They are exactly how people end up paying every month for gigabytes that expire untouched:
They buy a buffer "just in case"
A household picks a large plan so they will never run out, then uses a fraction of it month after month. The unused data does not roll over, so the extra dollars buy nothing but peace of mind they did not need.
They size off one unusual month
Someone checks their data right after a holiday or a big download, sees a spike, and locks in a plan built for their busiest month ever. Every normal month after that, they pay for headroom they never touch.
They never move heavy video to Wi-Fi
A heavy streamer watches hours of video on mobile out of habit, even at home, and assumes they simply "need a big plan". Shifting that viewing to Wi-Fi would drop their real number enough to move down a tier.
They pay the major when a reseller would do
A customer stays with a major network on a big-data plan when a cheaper brand rides the same towers with the same allowance. They are paying a premium for a logo, not for more data or better coverage.
The insider insight
The "just in case" buffer is a pricing tool, not protection
Here is the part the plan pages do not spell out. Carriers know that running out of data feels worse than wasting it, so they market the larger plan as the safe choice. But the cost of the buffer is certain and the benefit is rare: you pay for the big allowance every month and only ever brush the cap occasionally, if at all. The fear does the selling, and the unused gigabytes are quiet margin.
The non-obvious truth: your real data number is almost always smaller than you think, and it is sitting in your carrier app right now. A typical light user runs well under 10 GB a month, dominated by a few hours of video. The winning move is to read your actual three-month usage, add a 20 per cent buffer, move heavy video to Wi-Fi, and buy the smallest plan that comfortably covers that. The cap you are scared of is usually far above what you will ever use.
So the practical lesson is to stop shopping for the biggest number and start shopping for the right size. The large plan is real, it is just rarely the thing you actually need.
Grounded in the analysis
What you should actually do
Moves that follow from how mobile data really works in Australia, not generic advice.
Read your last three months of usage
Open your carrier app, or iOS Settings then Mobile, or Android Settings then Network. Note your data used for each of the last three months and take the average, so a single spike does not skew you.
Add a small buffer and pick the size
Add about 20 per cent to your average for a busy month and choose the smallest plan that covers it. Skip the "just in case" jump; unused data expires and only the carrier benefits.
Trim the heavy items, then shop the network
Move heavy video to Wi-Fi and switch on data-saver to lower your real number. Then find the cheapest brand that rides the network covering your area with that allowance included.
Compare mobile plans and right-size to your real usage on a network that covers where you live.
Current figures, last updated 2026-06-15
Key facts about mobile data in Australia. Sources: carrier apps and device OS data tools for usage, the Australian Communications and Media Authority (acma.gov.au), and the Telecommunications Industry Ombudsman (tio.com.au). Per-activity data and plan sizes change often; confirm before relying on them.
The bottom line
Why this matters right now
As plans grow and carriers push ever-larger data allowances, the marketing leans harder on the fear of running out. The gap that decides your value is not between a big plan and a small one, it is between the people who size to their real usage and the people who pay every month for a buffer they never touch. Spend five minutes reading your last three months in your carrier app, add a small buffer, move heavy video to Wi-Fi, and get that allowance from the cheapest brand on the network that serves you. That is how you turn your data plan from a fear-driven overspend into something sized to what you actually use.
Common questions
A Selectra expert answers your data questions
You have three easy ways. The quickest is your carrier app (Telstra, Optus, or whichever brand you are with), which shows your usage this billing period and usually past periods too. On an iPhone, open Settings then Mobile (or Mobile Data) and scroll down to see usage by app. On Android, open Settings then Network and internet (or Connections) then Data usage. The carrier app is the most accurate for billing, because the phone counters can be reset and may not match your plan cycle exactly.
Look at your real average over the last three months rather than guessing. Most light users (browsing, messaging, a little streaming) sit well under 10 GB a month, while heavy video streamers can run far higher. Add a small buffer of around 20 per cent to your average for a busy month, not a "just in case" jump to a much bigger plan. The honest target is your real usage plus a little headroom, not the biggest number a carrier will sell you.
One month can mislead you. A holiday, a big download, or a month away from home Wi-Fi can spike your data well above normal, while a quiet month understates it. Looking at the last three months smooths out those one-offs and shows your genuine baseline. Size your plan to that typical figure plus a buffer, so you are not paying every month for the data you used once during an unusual one.
A short list does almost all the damage. Video streaming is by far the biggest: about 1 GB an hour for HD, and several times that for 4K. Hotspotting (tethering a laptop or tablet) is next, because it pulls full desktop pages and updates. Large downloads and app or system updates also add up. By contrast, browsing, email, messaging and music streaming are light. Control the heavy few, or move them to Wi-Fi, and your data needs shrink fast.
Usually it is just more expensive. The fear of running out makes a large plan feel like insurance, but unused data simply expires at the end of the month, so a "just in case" buffer is mostly margin for the carrier. A right-sized plan plus a small buffer covers a busy month, and if you do go over, many plans now slow your speed rather than charge excess fees. Check what happens when you exceed your allowance, then size to your real usage rather than to your fear of the cap.
Often, yes. MVNOs (smaller brands that resell the three networks) frequently offer the same data allowance on the same towers for less than the major that owns the network. The brand on your bill is not the same as the network your phone connects to, so a reseller on Telstra or Optus can give you the same coverage and data for a lower price. Once you know your real data number, you can shop it across brands on the network that covers where you live.
