How Much Mobile Data Do I Need?

Most people pay for more mobile data than they actually use. This guide explains how to work out the right allowance for you, from 5GB up to unlimited to reflect current plan sizes and typical usage patterns.

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Reviewed by: Phil Brown, founder of SIM Only Finder. Phil previously worked in UK mobile retail at Three UK, advising customers on SIM plans, contracts, and network choices. He has spent over a decade running consumer comparison platforms and reviews networks and SIM-only deals based on that hands-on industry background. About the author

Last reviewed: July 2026. Updated regularly to reflect current plan pricing, network changes, and roaming policies.

How we put this guide together

To put this guide together, we reviewed the data allowances offered across the main UK networks and MVNOs, checking typical plan tiers, the pricing gaps between allowances, and fair usage terms directly against each network's published terms. Usage figures for common activities are drawn from published app and network guidance and are estimates rather than exact measurements, because real consumption varies with video quality settings, handset, and how much content is cached rather than streamed fresh.

Quick answer: how much data do most people need?

For most people, somewhere between 20GB and 50GB a month is enough. That covers everyday browsing, messaging, maps, music, social media, and a reasonable amount of video away from Wi-Fi.

You need less than that if you are connected to Wi-Fi at home and at work for most of the day and you rarely stream video on mobile data. You need considerably more if you commute daily without Wi-Fi, stream video regularly on the move, or use your phone as a hotspot for a laptop or tablet.

The single most useful thing you can do before choosing is check what you actually used over the last three months, rather than guessing. Almost everyone guesses high.

How to work out how much data you need

Start with your real usage rather than an estimate. Your network app or online account will show your monthly data consumption, usually with a few months of history behind it. Take an average across three months rather than picking a single month, because one unusually quiet or unusually busy month will skew the answer.

Add a buffer of roughly 20 to 30 per cent on top of that average. This covers the months where something changes: a holiday, a period without home broadband, a new commute, or a stretch of working somewhere without reliable Wi-Fi.

Then consider whether your circumstances are likely to change during the contract. This matters far more on a two year deal than a rolling one. If you are unsure how your usage will develop, a 30-day SIM only deal lets you adjust your allowance month to month rather than committing to a guess.

How much data common activities use

These figures are approximate and vary by app, quality setting, and whether content is cached or streamed fresh each time.

• Standard definition video streaming: around 1GB per hour
• High definition video streaming: 3GB or more per hour
• Music streaming: roughly 40MB to 150MB per hour depending on quality
• Video calling: around 500MB to 1GB per hour
• Social media browsing with autoplay video: highly variable, but 1GB to 2GB a day is realistic for heavy users
• App or game downloads and updates: 1GB to 4GB in a single session
• Maps and navigation: typically under 100MB an hour

The pattern worth noticing is that video dominates. Messaging apps, email, browsing, and navigation barely register by comparison. If your data disappears faster than you expect, video streaming or autoplay in social apps is almost always the reason, not the things people tend to blame.

Which data allowance should I choose?

Once you have a monthly average, the tier you need usually becomes obvious. The tiers below reflect how UK networks actually package their plans in 2026.

5GB to 10GB

Suits people who are on Wi-Fi for most of the day and use mobile data mainly for messaging, maps, music, and light browsing. It does not comfortably support regular video streaming away from Wi-Fi. This is also the tier where the cheapest plans live, and you can see the entry level of the market on our £5 SIM only deals page.

Best for: Light users with reliable Wi-Fi at home and work, second phones, and anyone keeping monthly costs to a minimum. Our full breakdown is in is 10GB of data enough.

20GB to 50GB

The mainstream tier, and the right answer for most people. It covers everyday use plus a meaningful amount of video and music away from Wi-Fi without requiring you to think about consumption. Competition is strongest here, so the price gap between this tier and the one below it is often smaller than people expect.

Best for: Average smartphone users who want to stop monitoring their usage entirely without paying for unlimited. See is 30GB of data enough for the detail.

100GB and above

Suits heavy users, daily commuters without Wi-Fi, and anyone regularly tethering a laptop or tablet. In many cases a 100GB plan costs noticeably less than an unlimited plan from the same network while covering usage most people never reach.

Best for: Heavy users and regular tetherers who want unlimited-style freedom without the unlimited price. See is 100GB of data enough.

Unlimited

Suits people whose usage is genuinely unpredictable month to month, or who use mobile data as a primary connection rather than a supplement. It removes the risk of running out entirely, which has a value of its own if you rely on your phone for work.

Best for: Anyone using mobile data as their main connection, or whose month to month usage varies too much to size accurately. Compare current plans on our unlimited data SIM only deals page.

Should I choose unlimited data?

Unlimited is the right choice for fewer people than choose it. The honest test is whether you have ever actually run out of data on your current plan. If you have not, you are paying a premium to remove a risk you are not exposed to.

The jump from a large fixed allowance to unlimited typically adds several pounds a month. Over a 24 month contract that is a meaningful sum for data you may never use. Where unlimited genuinely earns its price is unpredictability: if some months are quiet and others are heavy, sizing a fixed allowance accurately becomes impossible and you end up either overpaying or running short.

It is also worth knowing that unlimited plans are not entirely without limits. Fair usage policies allow networks to reduce speeds at very high consumption levels, and tethering is sometimes capped separately even when the main allowance is not. Our guide to whether unlimited data is really unlimited covers where those thresholds sit on each network.

How to avoid paying for more data than you need

The most common mistake is choosing based on your heaviest month rather than your average, then adding a buffer on top of that. This compounds a worst case into a permanent monthly cost. Use the average, then buffer once.

The second is assuming a bigger allowance is always better value. It sometimes is, particularly at the 100GB mark where pricing can undercut unlimited from the same network, but a mid-tier plan matched to your real usage usually wins on cost.

Data rollover is worth factoring in if your usage varies. A plan that carries unused data into the following month effectively smooths out quiet and busy periods, which can let you size down a tier. Our guide to which networks offer SIM only data rollover covers who offers it and how the terms differ.

Finally, factor in mid-contract price rises. A plan that looks cheaper today may not be cheaper across a two year term if the network applies annual increases while a rival holds prices flat. Our guide to SIM only mid-contract price rises explains which networks raise prices and by how much.

FAQs

How much data does the average person use?

Typical UK smartphone usage sits well below the allowances most people buy. Someone with home and workplace Wi-Fi who streams video occasionally on the move will often land between 10GB and 30GB a month. Heavy video use or daily commuting without Wi-Fi pushes that figure up sharply.

What happens if I go over my data allowance?

This depends on the network and the plan. Some stop data until your next billing period, some charge for additional data, and some automatically apply a bolt-on. Check which approach your network takes before choosing a tighter allowance, because the cost of the wrong assumption varies considerably.

How much data should a child's plan have?

Children tend to use less than parents expect, because school and home are usually covered by Wi-Fi. A smaller allowance with a spending cap is normally the better structure, and our guide to the best SIM only deals for kids covers the controls each network offers.

Does tethering use more data?

Tethering does not consume data at a different rate, but laptops and tablets tend to use far more than phones do. Desktop websites are heavier, and software updates can run to several gigabytes. If you tether regularly, size your allowance for the laptop rather than the phone.

Conclusion

Choosing a data allowance is mostly an exercise in resisting the urge to over-buy. Check three months of real usage, add a modest buffer, and pick the tier that fits rather than defaulting to unlimited for peace of mind.

If your usage is genuinely unpredictable, or you rely on mobile data as your main connection, unlimited is a reasonable choice. For everyone else, a mid-tier or large fixed allowance almost always costs less across the life of a contract, particularly once mid-contract price rises are taken into account.

How to check your current data usage

1. Open your network app or online account. Every UK network shows current and historical monthly data usage here, usually with at least three months of history.
2. Check your phone settings as a cross-reference. On iPhone this is under Settings then Mobile Data. On Android it is under Settings then Network and Internet then Data Usage. Reset the counter at the start of a billing cycle for an accurate month.
3. Take a three month average and add 20 to 30 per cent. That figure is the allowance to shop for.
4. Compare deals at that tier. If you are switching network and keeping your number, our guide to keeping your number when switching to SIM only covers the PAC process.

Editorial policy

This guide is produced by SIM Only Finder to help consumers compare mobile data allowances across UK networks. Network terms, pricing, and plan availability are checked regularly and updated to reflect current offers. Always confirm current terms directly with the network before signing up.