How much data do you actually need?
A practical way to size your allowance using your own usage rather than guessing — and when unlimited is worth the premium.
Most people buy more data than they use, or panic-buy unlimited after one bad month. Five minutes with your phone's settings gives you a much better answer than a guess.
Key takeaways
- Check three months of usage in your phone's data settings first.
- Add headroom for holidays, tethering and video calls.
- Under about 50GB a month, a fixed allowance is usually cheaper.
- Unlimited buys certainty rather than raw volume for most people.
Most people buy more data than they use, or panic-buy unlimited after one bad month. Five minutes with your phone's settings gives you a much better answer than a guess.
Key takeaways
- Check three months of usage in your phone's data settings first.
- Add headroom for holidays, tethering and video calls.
- Under about 50GB a month, a fixed allowance is usually cheaper.
- Unlimited buys certainty rather than raw volume for most people.
Measure before you buy
Both iOS and Android record mobile data use by billing period. Look at three recent months rather than one — a single heavy month usually reflects a holiday or a broadband outage, not your normal pattern.
Take the highest of the three, add roughly a third for headroom, and shop for the nearest allowance above that number.
What actually uses your data
Video is the dominant factor. Music streaming, messaging, maps and email are small by comparison, which is why two people with similar screen time can have wildly different bills.
- Streaming video — by far the biggest consumer, especially at high quality
- Video calls — significant on long or frequent calls
- Tethering a laptop — depends entirely on what the laptop does
- Music, maps, messaging, email — modest in comparison
When unlimited makes sense
If you regularly pass 50GB a month, or your usage swings unpredictably, unlimited removes the risk of out-of-bundle charges and is often close in price to a large fixed allowance. Below that, a fixed allowance is normally cheaper over a 24 month term.
Remember that unlimited is for normal single-device use and that roaming on it is capped separately.
Tablets, routers and dongles
If the data is for a router, tablet or dongle rather than a phone, a data-only mobile broadband SIM is designed for that and priced accordingly — there is no point paying for calls and texts you can't use.
Frequently asked questions
Where do I find my data usage?
On iPhone, Settings › Mobile Data. On Android, Settings › Network & internet › Data usage. Check three recent billing periods.
Is 50GB a lot of data?
It covers heavy everyday use for most people. If you consistently exceed it, unlimited is usually the better value and more predictable choice.
Can I change allowance mid-contract?
Moving a connection onto a new tariff restarts a fresh 24 month period, so it is worth sizing the allowance correctly at the outset.
Next steps
Frequently asked questions
Where do I find my data usage?
On iPhone, Settings › Mobile Data. On Android, Settings › Network & internet › Data usage. Check three recent billing periods.
Is 50GB a lot of data?
It covers heavy everyday use for most people. If you consistently exceed it, unlimited is usually the better value and more predictable choice.
Can I change allowance mid-contract?
Moving a connection onto a new tariff restarts a fresh 24 month period, so it is worth sizing the allowance correctly at the outset.
Deals mentioned in this guide
Prices include VAT and show the saving against the network’s own published price where a like-for-like plan exists.
O2 Unlimited
Unlimited streaming and tethering
Fixed for the full 24 month term
Compared against O2 direct, you save £192 over the 24 month term
That’s £8/month less than their £23 price for the same allowance.
Unlimited
Data
24 months
Contract
Vodafone Unlimited
Unlimited streaming and tethering
Fixed for the full 24 month term
Compared against Vodafone direct, you save £216 over the 24 month term
That’s £9/month less than their £26 price for the same allowance.
Unlimited
Data
24 months
Contract