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Extra charges for data over your limit: best and worst networks

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We compare the cheapest and most expensive UK mobile networks for extra data costs on your bill if you go over your monthly allowance. Last updated: 20th January 2022.

Going over your data limit

Different ways you’re charged for going over your data limit

Some cogs

It’s important to know how much data you’ll actually use before you buy a pay monthly deal. If you end up eating through your whole monthly allowance you’ll have to pay to get more (or turn off data until your next month).

The extra charges for going over your allowance vary by network. The simplest way of doing this is charging per MB or GB you use after you get through your data, but few networks do this.

Some networks will sell you chunks of data (often called add-ons / passes / bolt-ons and so on) for you to use after you’re out of data. The best networks will let you keep your added-on data for longer.

Similar to that, some networks will make you pay a monthly data add-on on top of your monthly bill. If you forget to cancel this you could end up continuing to pay for it even if you don’t need it.

Here we’ll take you through how all the UK networks charge you for extra data and how they compare with each other based on cost and convenience.

How the networks compare

Our favourite network for extra data charges is SMARTY

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Three’s low-cost sub-brand SMARTY have the fairest and simplest way of charging for extra data. Once you run out of data you can just buy an add-on. These are charged at a simple to remember 1GB for £1.

That’s a much better rate than most other networks. What makes them even better is that the data you buy never expires. So if you only need 50MB at the end of the month you can buy 1GB and continue to use it later on.

It’s also easier to avoid going over your data as all their plans are on rolling 1-month contracts. So if you find your data amount doesn’t suit your needs, you’re free to change it for your next month.

Useful link: Our full SMARTY review

VOXI, Tesco Mobile and Sky are also decent choices

VOXI logoTesco Mobile logoSky logo

One-off passes, fair prices

Our next choice is another sub-brand: VOXI, a sub-brand of Vodafone. With VOXI, if you run out of data you can choose to buy your next month’s plan early or add a “data extra”.

1GB of added data currently costs £3 and will last for 30-days after you buy it (or until you use it up). That’s not too bad in terms of pricing, but paying for your next month early is better value for money overall.

With Tesco Mobile you can buy 1GB add-ons for £5 (other smaller/larger increments available) if you need. These last until your new monthly allowance is paid for, and is much better value than paying as you go.

Sky Mobile are also worth a look. Their extra charges are a little pricier at £6 per GB, but many other providers have much steeper extra data rates than that.

Useful links: VOXI review | Tesco Mobile review | Sky Mobile review

BT, Three, iD Mobile and Plusnet offer monthly add-ons

BT Mobile logoThree logoiD Mobile logoPlusnet Mobile logo

Add-ons renew themselves each month

While these networks might have similar or even cheaper rates than the ones above, you have to be careful because they will automatically renew themselves every month if you forget to cancel them.

Three let you buy a 1GB data add-on for £5 a month if you’ve used all your data. The reason we still consider theirs worse than Sky’s despite being cheaper is because it’s easy to forget that it renews itself.

It’s a similar story for Plusnet Mobile and BT Mobile, who charge £6 per GB which will automatically renew itself. Both also let you pay 10p per MB if your next month is about to start.

iD Mobile’s add-ons are a bit pricier at £7 per GB. Considering iD is a cheaper network, it’s odd that their data add-ons can be more expensive than your actual plan. You could pay a lot if you forget to cancel it.

Useful links: Three review | BT Mobile review | Plusnet Mobile review | iD Mobile review

The big main networks are a little pricier on one-off basis

Vodafone logoEE logoO2 logo

More expensive than average

With Vodafone you can get a one-off block of 1GB for £8 to keep you going until your next month. Of all the major networks, their charges are the most reasonable.

EE’s extra data charges are similar. You can take a one-time 1GB data pass costing £8.34 that lasts until your next month. They offer some cheaper renewable extra data add-ons, but there’s always a risk of forgetting to cancel.

O2’s extra data charges skyrocket above EE’s, with a one-off bolt-on costing £12 for 1GB. In all fairness there are cheaper add-ons with less data, but here we’re comparing them by GB per pound rates.

It’s best to take a plan that suits your needs, as buying extra data can become very expensive, very fast.

Useful links: Vodafone review | EE review | O2 review

Virgin Mobile’s daily charge could work out expensive

Screenshot of Virgin's data charges

More expensive than original plan

While Virgin Media are a relatively cheap mobile network for pay monthly plans, getting extra data once you’ve run out becomes incredibly expensive. They offer two ways of paying:

Firstly you can choose a £3 daily fee for 1GB usage per day. That’s not great unless you’ll use up the whole amount, otherwise you could pay £6 for using 100MB one day and 100MB the next, for example.

Or you can buy a one-off Data Add-On of 1GB for £10. This will last until your next monthly payment and is only really worth doing if you’re three or more days away from your next month.

Either way, we think Virgin will work out more expensive than all other networks. If you’ve got only one day left then taking the renewable daily charge can be worthwhile, just remember to cancel it.

Useful link: Virgin Mobile review

Only a few networks just let you pay per MB

giffgaff logoiD Mobile logoBT Mobile logoPlusnet Mobile logoHones Mobile logo

Just pay for what you use on these networks

One one hand it’s good when networks let you pay per MB, cause it means you’re less likely to pay for a data add-on you won’t entirely use. But if you’ve got a while left before your next month then they can be expensive.

Honest Mobile have the cheapest rate of 2.25p per MB. It’s great if you only need a little data, but 1GB would cost you £22.50! They also have few choices for SIM only plans, so you’re more likely to go over in the first place.

While 10p per MB on giffgaff seems reasonable enough if you’ve only got a short time until your next month, if you needed 1GB then you’d have to pay £100. You’re better off paying for your next month early.

Some of the networks we’ve already featured above let you pay per MB, and it can be a good choice if you’ve only got one or two days until your next monthly payment.

iD Mobile, Plusnet and BT Mobile all let you do this and all charge 10p per MB. The charge will be added to your monthly bill, unless your spending cap prevents this (which will stop the add-on from working).

The rest of the networks make you buy their add-ons to keep your data working, rather than letting you pay as you go per MB.

Useful link: giffgaff review

More network ranking guides

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