Choosing the right data allowance is one of the most practical decisions when picking a phone contract. Too little and you risk overage charges or reduced speeds. Too much and you are paying every month for data you never use.
This guide explains what each data tier covers in real use, what unlimited data actually means in practice, and how to work out what you genuinely need before you commit to a contract.
Reviewed by Phil Brown, founder of Mobile Phone Finder. Phil has worked in the UK mobile industry, including retail management at Three UK, and has spent over a decade building consumer technology comparison platforms. About the author
Why data allowance matters more than most people think
Monthly price is usually the first thing people compare. Data allowance is often the second. But the two are closely linked. The cheapest monthly price on a deal usually comes with a smaller data allowance, and understanding where your usage really sits can save you money without changing how you use your phone.
As a rough UK benchmark, Ofcom reported average monthly mobile data use per mobile data user at 10.6GB in 2024. That figure puts common plan sizes into useful context. Some people buying unlimited plans are using far less data than they expect, while others on fixed allowances are regularly running short.
Getting this wrong in either direction has a cost. Underestimate and you either pay for add-ons or spend the last week of every month on WiFi. Overestimate and you hand money to a network for capacity you never touch.
How to check how much data you currently use
The most reliable starting point is your existing bill or network account. Most networks show your monthly data usage in their app or online account, and looking back over three or four months gives you a more realistic average than a single month that might be unusually high or low.
If you do not have easy access to your bills, you can also check directly on your phone. On iPhone, go to Settings, then Mobile Data, and scroll down to see usage per app for the current period. On Android, go to Settings, then Network, then Data Usage. Bear in mind the in-phone figures reset when you manually clear them, so they may not reflect a full billing period.
Whichever method you use, look at your average over several months rather than your peak. A holiday or a period without reliable WiFi can skew a single month significantly.
What each data allowance covers in practice
1 to 5GB
Enough for light, mostly WiFi-based use. Browsing, messaging apps, emails, and occasional social media scrolling without video autoplay will fit comfortably in this range. Streaming even one hour of standard definition video per day will push you toward the top of this tier quickly.
This is a realistic allowance if your phone is on WiFi at home and at work most of the day, and you rarely use it for video or music streaming on mobile data.
6 to 15GB
A practical middle ground for moderate users. This covers daily social media use including short video content, occasional music streaming, maps and navigation, and some video calls. You would need to be a bit more mindful about video streaming, but it is manageable with simple habits like downloading content on WiFi before travelling.
Based on Ofcom's reported UK average of 10.6GB per month, many people fall into this range even if they assume they use more.
20 to 50GB
Comfortable territory for regular streamers and people who use their phone heavily away from WiFi. This covers daily music streaming, regular video streaming at standard or high definition, frequent video calls, and occasional mobile hotspot use for a laptop or tablet.
If you commute and stream video on the way to work, or regularly tether your laptop during the day, this tier covers most scenarios without restriction.
100GB and above
Best suited to very heavy users, including people who hotspot frequently, work from their phone, stream in high definition regularly, or use mobile data as a backup when home broadband is unreliable. In practice, many people on 100GB plans never get close to using it all.
The gap between 50GB and 100GB is often smaller in practical terms than the price gap suggests. It is worth checking whether a 50GB plan would genuinely be enough before paying the premium.
Unlimited data
This is where things get more complicated than the label suggests.
What unlimited data actually means, and what it does not
Unlimited plans are not all identical, and the differences between them are more varied than a simple unlimited but not really pattern. What you are actually buying depends on the specific network and tariff.
Some unlimited plans are effectively uncapped for everyday UK phone use. Others apply different kinds of restrictions. Some tariffs use speed tiers, while others include conditions around private use, tethering, roaming, or device type.
The practical implication is that you need to read the specific plan terms rather than assuming all unlimited plans work the same way. The restrictions that exist are more likely to involve speed tiers, acceptable use conditions, tethering terms, or roaming limits than one universal model.
Tethering and hotspot use
This is one of the areas where unlimited plans vary most in practice. Some networks apply limits to how much data can be used as a hotspot even when the core allowance is unlimited. This is often buried in the plan details rather than the headline pricing. Before committing to an unlimited plan, check the terms specifically for hotspot or tethering restrictions. This is a common source of confusion on plans that appear fully unlimited at first glance.
Speed tiers
Some unlimited plans offer unlimited data but at a capped maximum speed rather than full network speed. This is worth checking if you intend to use your data for video streaming, tethering, or mobile working, where speed matters as much as volume.
Network congestion management
On some plans, customers may experience slower speeds during very busy periods as the network manages overall demand. This varies by network and location, but it is worth being aware of if consistent speed matters to you.
When unlimited is genuinely worth it
If you regularly use more than 50GB per month, hotspot other devices often, or simply do not want to think about your data usage at all, unlimited removes the friction of monitoring usage and may be worth the premium. If you consistently use well under 50GB per month, a large fixed allowance will often do the job just as well at a lower price. Always check the current tariff terms for the specific plan you are considering rather than relying on general assumptions about what unlimited means.
A realistic guide to data use by activity
To give you a practical sense of what data activities actually consume:
Streaming music uses roughly 40 to 150MB per hour depending on quality. An hour of standard definition video streaming uses around 1GB. High definition video uses 3GB or more per hour. A video call uses around 500MB to 1GB per hour. Social media browsing with video is highly variable but 1 to 2GB per day is realistic for heavy users. Downloading a large app or game update can use 1 to 4GB in a single session.
These figures are approximate and vary by app, quality settings, and whether content is cached or streamed fresh each time.
Common mistakes when choosing a data allowance
Choosing based on your best month
If you had unusually low data use during a period when you were mostly at home or on holiday with good WiFi, that month is not representative. Use a three-month average if possible.
Not accounting for changing habits
If you are taking out a 24-month contract, think about how your usage might change. A new commute, working from home less, or a change in how you use streaming services can shift your data needs significantly over two years.
Assuming a bigger allowance is always better value
The jump from 100GB to unlimited often costs more each month. Over a 24-month contract, that can add up quickly for data you may never use. A 50GB or 100GB plan with a clear sense of your usage is often better value than defaulting to unlimited for peace of mind.
Assuming video calls and messaging apps use large amounts of data
App-based calls and messages such as WhatsApp, FaceTime, and similar services use relatively little data compared with video streaming. A one-hour video call uses roughly 500MB to 1GB. These are unlikely to be the main driver of high data use. Video streaming on mobile data is a much more common cause of unexpectedly high consumption.
How to choose the right allowance
Start with your current average monthly usage from your bills or network account. Add 20 to 30 percent as a buffer for months where you use more than usual. If the result sits comfortably within a fixed allowance tier, choose that tier rather than defaulting to unlimited.
If you regularly hotspot other devices or your usage is genuinely unpredictable from month to month, unlimited may be worth considering. Check the specific plan terms for tethering limits and any speed conditions before committing.
If you are comparing deals and want to filter by data allowance, you can compare pay monthly deals across UK networks and retailers to find plans that match your usage.
Frequently asked questions
Is unlimited data really unlimited?
It depends on the specific plan and network. Some unlimited plans are effectively uncapped for everyday UK phone use. Others apply speed tiers, tethering limits, or acceptable use conditions. Always check the current tariff terms for the plan you are considering rather than assuming all unlimited plans work the same way.
How much data does streaming use?
Standard definition video uses around 1GB per hour. High definition uses 3GB or more per hour. Music streaming uses 40 to 150MB per hour. These are the biggest drivers of data use for most people.
What happens if I go over my data allowance?
This depends on your network and plan. Some networks stop your data until the next billing period. Others charge extra or prompt you to buy an add-on. Check your plan terms, and if you regularly exceed your allowance, moving up to the next tier is usually better value than repeatedly paying for extra data.
Can I change my data allowance mid-contract?
On many pay monthly contracts you can upgrade your plan or add a data bolt-on, but you cannot usually downgrade until your contract ends. If flexibility matters to you, a 30-day rolling plan may be a better fit than a fixed-term contract.
Summary
Most people need less data than they think. Check your bills or network account before choosing a plan and use a three-month average rather than a single month. Ofcom reports UK average mobile data use at 10.6GB per month, which puts common plan sizes into context. 1 to 5GB suits light WiFi-reliant users. 6 to 15GB covers moderate everyday use. 20 to 50GB is enough for regular streaming and occasional hotspot use. 100GB and above is for heavy users. Unlimited plans vary significantly by network and tariff, so check the specific terms for speed tiers, tethering limits, and acceptable use conditions before committing.
Sources and methodology
Usage figures in this guide are based on the following:
- Ofcom Connected Nations and Communications Market Reports, including average UK mobile data use of 10.6GB per month reported for 2024
- Network tariff terms and fair use policies published by UK mobile operators, reviewed March 2026
- Approximate data consumption figures based on app and service provider guidance
- Editorial judgement based on typical UK mobile phone use patterns
Network terms and tariff conditions change regularly. Always check current plan details directly with the network before purchasing.
